Chrysler 426 Hemi in depth dyno test and analysis using modern empirical and simulation techniques

Posted on July 15, 2012 by Tiger Core

426 Hemi engine sporting dual quad Carter Carburation and Dual plane intake

In 1964 when the 426 Hemi was introduced it was primarily a racing engine. It was on the 23^rd of February when four Hemi-powered Mopars swept the Daytona 500 and finished finishing first, second third and fourth. This single event took the racing world by storm and ultimately led NASCAR to impose stricter production rules on Chrysler. As a result they would be required to produce several thousand Hemis in regular production vehicles rather than only a few blueprinted Hemi motors each production year. This is what led to street Hemi which was a slightly detuned motor found initially in 1966 B body Dodges and Plymouths. The 426 street hemi was rated at 425 Bhp but it’s been long said that these engines were under quoted during certification from the factory for insurance purposes. But just how much power did those ‘King Kong’ Hemis make by todays standards?

As well as addressing the above It is the intension of this technical article to cover a few further points. To go further we would like to introduce to you the concept of a 1 dimensional fluid dynamics engine performance prediction code. They’re not a new concept and quite a few exist. Now it is important not to confuse these with budget aftermarket codes such as Desk Top Dyno, Performance Trends or Dynomation: the commercial codes are far more sophisticated and extensive in scope. They’re often referred to as 1-D cycle simulation or thermo-fluids codes. OEMs as well as racing use them to great effect characterizing prototype engines to minimize dyno testing, optimising and to gaining further insight into engines. There are commercial codes available such as GT Power and Ricardo Wave and these are the codes that OEMs usually use although some manufacturers have been known to develop their own in house software for these purposes (Lotus cars and Ford Motor company have done so in the past). We don’t wish to get bogged down on the academic technical details of the ins ands outs of 1 D code. We can summarise by saying that our code is our own, a spin off written from university days and proven to be extremely accurate time and time again when compared back to back with measured dyno data. The code simulates unsteady, compressible gas flow through the induction and exhaust systems of multi-cylinder spark ignition engines. It solves for “quasi-3D” of the Navier Stokes equation using an explicit ,second order , finite difference numerical solution technique solving for mass, energy and momentum. A well built model extensively correlated to measured engine dyno data usually falls within 3% of the data. Once this model is established the effects of cam profile or changes in exhaust are quite easily and accurately reflected. In addition to our 1 D code we also had access to an engine dyno at Rennsport Systems and an original 1965 engineering technical development report by Chrysler engineering complete with extensive dyno data from their Highland park facility. It was upon this solid foundation (along with our own extensive empirical engine test data database) that we built our simulation model. It’s fair to say that this is probably one of the first applications of extensive 1D modeling to such a venerable engine.

Binder for original 1965 Chrsyler Hemi report

Hot Bare Gross Dyno power curve from original Chrysler dyno report

What an engine is rated at is highly dependent upon its level of dress and the conditions to which it was tested. Before we go much further, it’s important to review the various old Chrysler definitions that correspond to their engines level of dress and testing conditions.

Cold Bare Gross: No air cleaner, released carburetor mixture, intake manifold heat passage blocked off, maximum power advance (MBT) set at each speed, laboratory exhaust system installed and exhaust heat valve open.

Maximum Torque @ rpm Maximum Power @ rpm

480 ft. lb @4400 480 Bhp @ 6000

Hot bare gross: This is the same as Cold Bare Gross except intake manifold heat is used.

Maximum Torque @ rpm Maximum Power @ rpm

472 ft. lb @4000 477 Bhp @ 6400

Laboratory Gross: Air cleaner installed, fixed jet carburetors (AFB- 4139 front, 4140 rear), Maximum power spark advance (MBT) set at each speed, crankcase ventilation valve operating, normal heat on the intake manifold (type of heat-exhaust), exhaust heat valve open, and laboratory exhaust system installed

Maximum Torque @ rpm Maximum Power @ rpm

474 ft. lb @4400 474 Bhp @ 6000

Full Net: Air cleaner installed, fixed jet carburetors (AFB 4139 front and AFB 4140 rear) normal heat on the intake manifold (type of heat exhaust), exhaust heat valve open, automatic spark advance set manually at each speed (#PF 1058 vacuum curve, #PF 4439 governor curve, set 12.5 degrees BTDC), car cooling fan (fixed mechanical) and exhaust system installed.

Maximum Torque @ rpm Maximum Power @ rpm

416 ft. lb @3600 390 Bhp @ 5600

So where do we go from here? It’s important NOT to take the dyno figures (even engine dynos) automatically as gospel without question: even methodically calibrated dynos show variance and several OEMs use this to their advantage (notice we didn’t even touch upon the minefield of after market dynos and chassis dynojets). Usually dynos are still very valuable when evaluating changes against an established baseline. The same level of healthy cautiousness should be used when reviewing the simulation data where the results are highly dependent on the assumptions and the code itself employs certain assumptions in its theory. This level of healthy pragmatism combined with an empirical database of what is realistic and what falls outside what is plausible will allow us to really get a good feel and understanding of the engine. We correlate the 1 D code model, fastidiously going over every engine system on a component by component basis. It’s a relatively easy task to get the simulation model to match a fixed set of dyno data. What is more useful is to see if the model can track changes in cam profiles/timing, exhaust system and intake geometry and still predict faithfully. The first task is to match the simulation to the measured engines airflow or volumetric efficiency curves (VE), An engines VE curve looks very much like the torque curve shape and various parts of the engine effect that curve depending on the engine rpm and load.

The figure below shows just how well a well correlated 1-D cycle sim model can capture cam timing changes in volumetric efficiency. The magnitude of the trends of these changes are captured very accurately. On the dyno the 276 period Hemi cam was timed at a maximum opening point of 104, 108 and 113 degrees timing ATDC.

If this was a project with an OEM we would outfit the subject engine with a network of pressure tappings, some static some water cooled kistler Real time dynamic along with in cylinder pressure transducers but these are not available to us for this project unfortunately. The next figure shows a simulation model matched to intake , combustion chamber and exhaust pressure tappings showing capturing of the tuning waves at various engine speeds for a 4.6 litre V8 to illustrate just how accurate a well tuned model can capture the real engine. This level of depth while useful is perhaps not required for this investigation though.

AVL Tippelman flowbench capable of measuring outright flow as well as tumble motion

Engine induction

The most influential part of the intake system of a naturally aspirated engine are the intake ports. The ports of the Gen 2 426 Hemi are its entire reason of being. Based on the Chrysler RB big block base engine the Hemi spherical cylinder head allowed not only larger valves to be accommodated in a cross flow arrangement, the angled arrangement of the valves meant that the port flows were not as sensitive to being shrouded by the bore or combustion chamber walls.

Generation 2 426 Hemi cross section

Dodge RB cross section

In addition to outright flow of the ports it is important to consider swirl motion, tumble motion as well as mean gas velocity. One thing we’re going to get straight is the dropping this aftermarket practice of using CFM figures at 28 inches of water to classify absolutely every cylinder head under the sun. This site will continually focus on engineering related topics closer to an OEM perspective following their typical methodologies and practices. The biggest issues with using CFM at 28 inches of water is that it only is an absolute measure of restriction and doesn’t show how efficient the port flows for its design. We will use flow coefficient relative to bore size- which we call ‘Alpha K’ and also flow coefficient relative to the valve inner seat diameter itself (Fc). Different OEMs prefer to use different conventions: Lotus cars like to use a reference diameter of the throat diameter of the port while Cosworth have been known to use both the valve outer head diameter and the inner seat diameter while Jaguar and Ford Motor company also use inner seat diameter. By far using the inner seat diameter is the most common within the industry. Alpha K is a measure of how well the port is feeding the cylinder and is usually quoted as a percentage. Flow Coefficient or Fc is typically expressed as a fraction and is a measure of how efficient a particular port flows. A good Alpha K number for a typical 4 valve chamber at a peak valve Lift is anything above 16%. An exceptional number is 22% or above again at peak valve lift. In other words an 18% Alpha K at near peak valve lift means your cylinder is being fed well. Anything above 16% Alpha K is rather exceptional for an old school 2 valve style port. For Fc at 0.3 L/D (valve lift over diameter ratio) a good efficient port will flow above 0.6, while a well optimized port may achieve 0.68 to 0.72 at 0.3 L/D. A good way to illustrate and understand this is to imagine a good efficient port that flows 0.72 Fc at 0.3 L/D but in the cylinder when Alpha K is calculated only a modest 11% is achieved. What this would say to me is that there is very little to be gained by porting anymore as the ports are flowing very efficiently but the ports along with the valve heads sizes and associated dimensions are likely too small for the engine cylinder size or bore. Ocassionally the reverse can also be true.

The first figure shows a flow comparison of various 2 valve engines over the past 40 years that shows Flow Coefficient plotted against L/D ratio (Lift over diameter ratio). Because both axis are normalized it is a convenient and fair way to compare different engine sizes and styles. The broken black line represents the CD=1 line and is drawn for 45 degree valve seats. It represents the upper limit at low lift flows (when you’re constricted by the annulus of the valve) and under normal circumstances you shouldn’t be able to flow higher than that. Judging against the CD=1 line is a good sanity check to see if the Flow bench or Computational Fluid Dynamics (CFD) data is trust worthy. If your flow is some what below the CD=1 line at low lifts its most likely due to flow shrouding from either the cylinder bore itself or possibly the combustion chamber.

First comment to be made is that the 1969 Dodge “906” cylinder head 440 cu in (RB big block) port flow coefficients are surprisingly similar to the 1997 LS1. Now bear in mind that this is port flow coefficient so this means that in terms of flow efficiency they’re similar. The Dodge has larger valves (52.83mm vs 51.23) so probably flows slightly higher outright (CFM) flow numbers than the small block LS1 not surprisingly. What is surprising is that a 1969 wedge layout port could be similar to a port that’s almost 30 years more modern. You could mention in cylinder motion and how this is important and needs to be factored in. In fact straight after this part of the article we do just that. The next observation is that it’s not difficult to see why back in 1965 the Gen 2 426 Hemi really did rule the roost. Its port flows from stock castings were head and shoulders above other stock castings and compare favourably with the Chevy LS6 from 2002 (which is a wedge design so admittedly has a harder job to flow as well). The 1987 2 valve BMW M20 is included there as this port is considered a benchmark in terms of flow and motion compromise: This cylinder head is an evolution of Apfelbecks work and his legendary ‘DreiKugelWirbel’ or ‘3 lobe vortex’ Chamber he outlined in the 1960s. This port/chamber layout is a shallow angled hemi (44 degree total included angle) with a low heat loss compact chamber , good squish and great in cylinder motion as we shall soon see. I’ve also included the flow performance of the 2006 Gen 3 Chrysler Hemi engine. In terms of outright flow characteristics the flow follows the CD=1 line well at low lifts and then increases to an unpresidented outright flow figure.

To assess the flow capability of a cylinder head fully the previous plot of Fc vs L/D should always be assessed along side Alpha K vs Valve lift. Here we can see that the Dodge RB heads and Chevy LS1 flow characteristics diverge when assessed relative to the bore diameter. This would seem to indicate that the 52.83mm Dodge valves are rather modestly sized for the bore size of 110mm. When viewed in context of the modest 84mm bore size of the BMW M20 this little port flows very well and compares favourably with the LS1 Chevy engine. Finally we can see that the Gen 2 426 Hemi flows very well compared to the other modern engines only behind the late 2006 Gen 3 Hemi and the Porsche 911 (993) cylinder head- a head which I included as it was considered a modern production benchmark for a 2 valve Hemi style port/chamber in terms of outright flow until recently. The 2006 Gen 3 Hemi has outstanding outright flow for its 99mm bore size that would be very good even for a 4 valve figure. It doesn’t fair so well for a modern design in terms of in cylinder motion as we shall touch upon next.

A high Alpha K value will have a direct bearing on specific output of an engine. This is because Alpha K will be a high value if outright flow is high and the bore diameter is smaller- and having high flow for a modest bore size is an ideal ingredient for high BMEP and high specific out put (a small bore is better in terms of thermal losses and smaller flame paths for better knock limit). The relationship of the valve head diameter to the bore diameter will have a direct bearing on the Alpha K value. The next plot shows a snapshot figure of Alpha K at a fixed L/D of 0.2. It is based on an empirical data base of several 2 valve engines and shows how our comparator engines compare with others (the grey shaded area).

The straight line represents the upper limit of outright Alpha K possible at 0.2 L/D from our empirical database. Engines below that straight diametric line COULD be using the energy available for outright flow for in cylinder motion. Or put another way, when below that line there is energy potential in the flow to be used for knock mitigation. This doesn’t mean that just because you’re below that line the energy normally available for flow IS used for in cylinder motion- just potential. It does mean that when you’re at the limit line you are very likely NOT making much in cylinder motion however. The graph shows that the Porsche 993 (M64) cylinder head as well as the Gen 3 2006 hemi represent the upper limit for outright flow for their Dv/Dcyl (Valve diameter to bore size) . Unfortunately these engines do not have a lot of in cylinder charge motion. The 1960s Gen 2 426 Hemi could flow better considering its Dv/Dcyl however , as subsequent plots will show, this engine doesn’t have much in cylinder charge motion either.

In cylinder motion can be resolved or classified as either tumble motion or swirl motion (in reality most port/chamber geometry) will tend to produce a combination of both to greater or lesser degrees. In cylinder tumble motion will typically tend to speed up burn near TDC and make an engine more resistant to knock and if optimized correctly can also give the engine ability to run stable lean combustion . An example of a high tumble 4 valve engine that is capable of running very lean is the Honda S2000. The plot shows a snap shot of Alpha K for 0.2 L/D again, versus tumble intensity as measured on our flow bench. The grey shaded zone represents the empirical data we have for several 2 valve engines. The curved broken boundary curves (in red, cyan and green) show valve angles of the cylinder head design as typically a deeper angled combustion chamber will show a better flow/tumble compromise (tumble motion at TDC typically doesn’t decay as much with a deeper chamber). However too deep a chamber and you’ll get excessive heat loss and your piston will need to be domed to attain the target design compression ratio will exacerbate the problem. It’s all a case of balance. The BMW M20 head produces the highest tumble intensity even though it still flows better than poor tumbling heads like the 1969 RB 440 Dodge and doesn’t flow a lot worse than the 1997 Chevy LS1 head. When viewed in context of the Dodge Gen 2 426 Hemi engines HUGE included valve angle of 58.5 degrees the engine produces very poor tumble and reasonable outright flow – although back in the 1960s it is unlikely that tumble motion and good combustion burn rate was a priority or even fully understood. The Porsche 993 head produces better tumble and good flow considering the size of valve in the bore size. Finally with the 2006 Gen 3 Hemi (34.5 total included valve angle) it’s obvious that the priority of the engine design was outright flow over in cylinder tumble motion. The twin plug arrangement of the new Hemi will no doubt help with knock mitigation and stable combustion (by shortening flame paths) and this is the reason why the ports were prioritized towards outright flow (See SAE paper 2002-01-2815). Just for comparison and to show how far a well developed 4 valve engine has come I’ve plotted the 4 valve Honda S2000 cylinder head figures on the same 2 valve plot space. The Flow-tumble motion compromise is in a totally different range.

In cylinder swirl motion is the other component widely considered. Typically this doesn’t benefit knock limit mitigation much but if done correctly can speed up burn rates (late in the cycle) and help with engine lean running capability. Engine lean running capability will benefit the engines ability for stable combustion with higher EGR rates also. At 0.25 L/D the BMW M20 head produces very respectable flow and a swirl ratio that is on a par with the LS1, Dodge 440 even the VW Polo 1.2. The Honda Jazz 2 valve makes a very high swirl ratio at the expense of flow. The Porsche M64 and Gen 2 426 Hemi cylinder heads produce the highest flow out of the bunch presented and the ports were not designed to impart swirl motion.

In summary the Gen 3 Hemi flows outstandingly well but with poor in cylinder motion- however its twin plug design will no doubt help in this area. The Gen 2 426 Hemi flows respectably even by todays standards compared to an GM LS6 engine, although there’s certainly room for improvement in these heads using modern techniques. The priority with the 426 Hemi was obviously not in cylinder charge motion. The stock 1960s Dodge RB ‘906’ cylinder head is surprisingly similar in Flow coefficient to the LS1 Chevy small block (one wonders how the previous LT1 engines faired) although the RB big block could benefit from larger valves. The 1980s 2 valve BMW M20 cylinder head represent a good compromise of both outright flow, in cylinder swirl and tumble motion. This probably explains why this engine produced the highest specific output for a NA 2 valve engine in its day with good resistance to knock and lean running ability. Not a lot of porting work would be required to significantly improve these heads in all areas. The Porsche 2 valve 993 head is not dissimilar to the Gen 3 Dodge Hemi. The priority wasn’t placed on in cylinder charge motion but again the design has a twin spark plug arrangement. We wouldn’t be surprised if the 993 Porsche cylinder heads were used as a benchmark by Chrysler to develop their Gen 3 Hemi heads.

Port velocities

If port flow was the only criteria to judge good ports, ports would end up being drain pipe sized (much like the less technically accomplished Detroit manufacturers tried in the 1960s with Tunnel ports and ‘Ram Air’ heads) presenting absolutely minimal restriction. In reality there is a compromise between port velocity and port flow. This fact is actually lost TODAY amongst some of the Korean manufacturers. Too large a port with slow port velocities and the in cylinder burn will be slow due to poor motion and slow momentum of incoming charge. This is doubly important on a carbureted engine where the flow is essentially wet with fuel droplets in suspension. To asses port velocities the port is split into the entry portion, mid portion (or trouser leg in the case of a 4 valve style head) and the throat. The guidelines used are calculated as mean gas velocity at peak power speed. Good design practice guidelines for a high performance engine are 100-110 metres per second , 90 to a 100 m/s and 70 to 80 m/s at the Entry/mid port/ and port throat respectively. These are rough guidelines and good engines can still stray outside these slightly. Engines with fully machined ports good flowing ports will tend to target higher velocities. The BMW S54 M3 engine for instance achieves 110./119/94.3 m/s at its 7400 rpm peak power speed.

With the design peak power speed of the Dodge 440 six pak engine of 4700 rpm and 6000 rpm for the 426 Hemi engine you can see that the port velocities of the two top big block Mopar muscle car engines are right in line with guidelines. It’s obvious that Chrysler engineers in the 1960s knew what they were doing and , as indicated, this wasn’t necessarily the case with their period peers.

Carburation and Intake Losses

Intake losses on cars with carburetters is a complicated matter and always a case of compromise. Not too big because you’ll lose driveability. Not too small or the carb becomes a major bottleneck. For most hot, dual-purpose cars, pulling about 0.9 to1.0-inch-Hg manifold vacuum at WOT, max rpm on the dyno is a good target. Now I’m quoting this figure using the Hot rodders norm of having no air cleaner or induction trunking fitted with the venturis of the carbs drawing straight from atmosphere. This is what’s known in the industry as Gross power figures and was the norm even for OEMS homologating back in the late sixties. Once you put on the period air cleaner and induction system you’re likely to be in the 1.15 to 1.35 inches of HG region. It’s quite an easy task these days however to source a less restrictive (but noisier) air cleaner induction set up for carbs that will bring this down to virtually no difference from the target 0.9-1 figure. These are all guidelines from racing experience but there are no guarantees. It’s impossible to know for sure how a carb will perform in a vehicle based on how it did on an engine dyno test in the lab. Every combo behaves differently when you’re actually out on the road with a lot of transient accelerations and various road gradients. What works in a featherweight car with a manual trans and 5-series rear-gears may not be ideal in a 3,700-pound car with a mild converter and 3.23:1 final drive.

Carburetor sizes usually quoted in inches refer to the diameter of the barrel. The Dual quad 426 Hemi tested in 1965 used a Carter AFB 4139 at the front and a AFB 4140 at the rear. These were chosen to minimize the cylinder to cylinder Air fuel ratio variance as much as possible. The barrel diameter or throttle bore diameter of the primaries were 1-7/16 and for the secondaries it was 1-11/16. This fed into a dual plane intake manifold which connected together equal phase (360 degrees apart) fired cylinders in sympathy with the firing order (which was common practice back then). What is more important than the barrel diameter and what was common practice to quote was steady state pressure drop across the carburetor as measured on a flow bench. Some manufacturers, such as Holley, would have this information readily available. It was more difficult to get this data from Carter but not impossible. We found out that the Carter AFBs used on the Hemi were rated at 570 CFM each. Flow capacity gives more important technical information than just the barrel diameter as for a given barrel diameter the venturi size can be different or other subtle but significant details that effect the 3 D flow and therefore the restrictiveness of the carburetor. The next thing to note is that most manufacturers rated carburetors in terms of DRY flow which is quite different to wet flow. Dry steady state flow is about 8% higher than wet. Wet flow is what is closer to how an engine is run. 4 barrel carburetors were typically rated at 1.5 inches of mercury pressure drop. We built a mock up of a steady state rig in simulation to mimmick the steady state pressure drop of the original carburetor test conditions. The restriction of the modeled AFB barrels and venturis were adjusted until the Carter ratings were obtained and this calibrated Carb model was placed into the engine simulation. The match to the 1.25 inches of depression of the actual running Hemi engine fell to within 10-15% even when Dry flow rating to wet flow was taken into account (the real engine carburetion was more restrictive). We went with the measured running engine depression. An engine runs dynamic pulsing flow that continually varies with time as distinct to the steady state rigs continuous pressure drop.

There could be a number of reasons for the less than perfect match up of restrictiveness of the carburetor rig data to the engine measured depression including unknown entry and exit conditions of the steady state test rig, subtle variations of the exit conditions of the mounted carb on the engine and unusual 3 Dimensional pulsing effects on the running engine that effected results.

Engine Camshaft profiles

A profile on profile comparison is shown in figure ##. The 426 Hemi solid tappet cam profile is shown up against to other notable pushrod engines: The Buick derived Rover V8 and a late Gen 3 5.7 Hemi. The first thing that is striking is the length and height of the ramps of the Gen 2 426 Hemi. This is in part due to the fact that we’re comparing a flat tappet solid lifter cam with hydraulic lifter cams (Rover V8 is a flat tappet hydraulic and the Gen 3 Hemi is a roller hydraulic). Despite this the height and length (read mild ramp rates) of the ramps seem excessive by modern day standards and will effect engines in cylinder residual level (blow back of exhaust gases back into the cylinder) at light loads and low speeds.

Closer examination of the 3 profiles shows that the Gen 2 426 Hemi cam flank accelerations are quite modest considering that it is a solid lifter profile (solid lifter profiles are usually able to have higher peak flank acceleration). It is lower than the Gen 3 Chrysler Hemi (which is a roller hydraulic) and the Rover V8 hydraulic flat tappet cam which is surprising. This is probably due to the age of the design and possibly the mass of the valve system (Tappet, pushrod, rocker arm, valve itself etc) of the Gen 2 Hemi. A glance at the profile velocities shows than the gen 2 426 Hemi with it’s wide 0.903 in diameter tappets allows highest peak velocities for a flat tappet cam compared to the Rover V8 (with its 0.842 in tappet diameter) but predictably the Chrysler Gen 3 with its roller tappets gives the most freedom to the cam designer by allowing very high peak velocities. Although the total cam period or duration of the Rover V8 and Chrysler Gen 3 are of a similar order as are the peak flank accelerations the Chrysler Gen 3 gets its considerably higher peak valve lift from higher acceleration across the cam nose. The Rover V8 and Gen 2 426 Hemi seem to have acceleration over the cam nose of a similar order.

In summary the Gen 2 426 Hemi profiles have long and tall ramps which are not good for performance and can probably be improved upon by adopting modern cam design practices. Similarly the nose and flank acceleration could also probably be further optimized with modern thinking. The long tall cam ramps will effect in cylinder residual levels and increase overlap thus adversely effecting cylinder to cylinder distribution (a particular problem on a high performance carbureted V8).

Engine friction evaluation/characterization

Engine friction is an often overlooked aspect of tuning and power. What is good for reducing friction will benefit fuel economy too. In the same way that increasing compression ratio benefits both also. We will look at engine friction of the 426 Hemi on a component by component level using a combination of our vast empirical test data base, our friction scoping tool which is a model based upon Heywoods model (see paper 2003-01-0725) but honed by applying it and adapting the theory to fit our empirical database and finally doing a sanity check to see if it all tallies up with measured motored engine data recorded. There are two ways to assess engine friction.

1) Using a motoring dyno

2) Using data from a fired dyno test from an engine outfitted with in cylinder cylinder pressure transducers (where it can be calculated from IMEP-BMEP).

Both methods have their pros and cons (it goes without saying that back in the 1960s when the 426 Hemi was conceived there were no in cylinder pressure transducers to get indicated mean effective pressure data). With the motoring test there is no way to account for increased local temperatures due to combustion (the colder wall temps during motoring will tend to give worse reciprocating friction than reality) and because there is no combustion the gas load on the bearings is a lot lower than a fired engine. These effects are somewhat self canceling and the numbers from motoring are not only good for relative differences but also a good first stab for absolute friction assessment. The in cylinder indicated transducer method is prone to errors because FMEP is small compared to IMEP and BMEP so any measurement error is amplified. The in cylinder transducer method is also very intrusive and involves machining and adapting cylinder heads to accept in cylinder transducers (more recently there are spark plug adaptor transducers but these are costly and hard to come by).

First of all we can see the projected rotational friction of the 426 Hemi crankshaft main bearings. The figure shows this up against favourable engines (green dotted curve), middle ground engines (yellow) and unfavourable engines (red dotted curve). This is perhaps a surprising result as it shows that the 426 fairs very well even compared our predominantly modern engine data base. The 426 Hemis main bearing size is 69.85mm which is similar to contemporary BMW V8 or older Porsche 928 engine, both of which are much smaller in capacity (7 litres versus under 5 litres) . However bearings are sized with peak cylinder pressure of the engine in mind and this is where the Hemi is mild compared to a European V8. I would even venture to say that the bearing could be made smaller especially when you consider the WIDTH of the Hemi bearings.

Reciprocating friction is the friction caused by the contact of the piston rings to the bore, the piston skirts to the bore and is also a function of the stroke length and engine speed or ‘mean piston speed’. In terms of piston design modern engines have come a long way. Skirts are a fraction of length they used to be and they are often of a slipper skirt design where they only exist on the thrust and opposite sides. Ring lands have come down dramatically and ring widths have come down, while rod length to stroke length ratios have increased. Rod length to stroke length ratio determines the angularity with which the thrust side of the piston is driven into the bore. As compression heights of pistons have come down rod length have been able to go up. Rod length to stroke ratio is an area where the Hemi and old RB big block excels compared to 1960s Big blocks of the time (Chevy Big Blocks deck height was only 9.8 inches vs the Mopars 10.72) .With all of this in mind it comes as little surprise that in terms of reciprocating friction the 426 Hemi is only slightly better than the mid band of benchmark contemporary engines out there. Typically when these engines get modified the pistons used have minimal slipper skirt design pistons with longer rods and small compression height. It is also common practice to grind down the stock con rod journal diameter of 60.2 mm down to the Chevy diameter of 55.9 mm which also helps bring down the reciprocating friction.

The valvetrain friction figure shows different boundaries of friction of various types of valvetrain from measured motoring data from our data base. Of all the types the highest friction is typically exhibited by poorly optimized sliding contact OHC valvetrain with hydraulic compensators (as part of the reciprocating mass). The lowest friction is usually exhibited by lightweight valvetrain outfitted with good roller design. The Cam-in-block design or pushrod is a venerable design but fairs reasonably well due to a number of reasons:

For a given V engine there is usually only one cam shaft and associated number of bearings rather than having 2 or 4 with an OHC layout.
The camshaft is located in a cooler part of the engine which helps the regime of lubrication (an OHC typically falls under mixed lubrication regime (which is the highest in terms of friction) while the cam in block will tend towards elastrhydrodynamic regime which has a lower coefficient of friction)

Out of the pushrod engines the graph shows the Gen 3 Hemi valvetrain friction (which doesn’t fair that well) with the 426 Gen 2 hemi and a Big Block wedge engine fitted with needle bearing rockers that have roller tips (but still flat tappet). What counts against the pushrod layout is the sheer mass of the valve train system and the number of rubbing surfaces. Without a doubt the way to better a pushrod layout is to go to roller tappets, rocker arms with needle bearings and rollers and a solid system with no hydraulic compensators which helps lower friction a lot. Out of the pushrod systems shown the 426 Hemi system fairs best mainly because it has solid lifters (and a relatively tame profiles).

The overall plot shows how well the empirical friction scoping tool compares against measured motored engine data (where pumping losses have been subtracted). The tool allows better understanding of where to optimize further when trying to raise the engines performance.

During the early to mid sixties directly driven fixed fans were commonly used to cool the big barges across the USA. The early Mopar big blocks were no exception. The engine used to homologate the Hemi in 1965 used a 4 blade fixed driven fan. This was tested in before and after testing (where dyno cell cooling was used to keep the engine cool) and the losses of the fan derived. It’s important to note that even with only a 4 blade fan the losses at full power are quite significant. The figure shows over 0.3 bar FMEP at full power. This amounts to 15 to 19 Bhp losses at peak power. It’s important to note that the Cold bare gross number of 480 Bhp doesn’t include this fan. The Lab Net number does include the direct driven fan. The later hemis and indeed the majority of engines post the 1970s started using viscous coupling clutched fans that slip above a certain engine speed and when the engine is receiving sufficient cooling (high vehicle velocities) and therefore reducing the frictional losses.

Engine combustion and ignition values

The final significant ingredient of the simulation model that is to match measured dyno data is combustion or some reasonable approximation that comes close to what was measured on the real engine. The full load ignition advance is shown in table.

These are optimized values that were obtained on our dyno at Rennsport and at the original test in 1965 in Chryslers Highland park facility. Optimised means MBT timing or where the ignition timing is swept until the best value of torque is obtained. Any more or less ignition and the torque falls off. When engine performance development engineers look at combustion of an engine they are concerned with the burn duration. This is typically split up into ignition delay and the main burn duration. The ignition delay is the time between when the spark is initiated and the spark nucleus is formed to when the laminar flame front gets underway to start burning across the combustion chamber. The ignition delay is hard to measure precisely so is usually quoted as 0-5% burn duration (or the time from ignition spark to when 5% of the in cylinder charge is burned). It’s important to bear in mind that the ignition delay will tend to increase with increasing engine speed even though the time taken is similar in milliseconds the time expended in crank angle becomes more. Similarly burn duration is usually quoted as 10-90% burn duration. The apparatus used to measure this are in cylinder pressure tranducers (as touched upon previously)-which were not available during the development of the 60s Hemi (or for our test work at Rennsport). The relationship between Ignition advance and burn duration and ignition advance and ignition delay is not a clear cut one and is effected by many parameters but given enough empirical measurement data clear enough patterns are exhibited to move forward. The next two figures show some of our empirical measured burn data hand picked for having ignition advance values of a similar value and similarly optimized for MBT timing. The burn duration and ignition delay values we picked to populate the model ended up being at the slower side of the bands as we already know that the Gen 2 426 Hemi engines ports and chamber offer little motion and therefore a quiescent burn (therefore a slow ignition delay and slower burn).

Posted in Automotive, Uncategorized | Tagged 440 6 pak, 906 cylinder heads, Alpha K, BMW M20 engine, BMW M3, BSFC, Chrysler, Dodge 426 Hemi, Dodge RB, Engine combustion. fast burn, engine friction, Engine modelling, Engine performance, Engine simulation, flow bench, Gen 3 Chrysler Hemi, GM LS1, GM LS6, GT Power, Honda Jazz engine, Honda S2000 ports, MANDY, Miscies, muscle cars, OHV, Porsche 993 M64 engine, port flows, port swirl motion, Port tumble motion, Pushrod, Ricardo Wave, simulation to dyno correlation, slow burn, torque curves, tribology, V8, Valvetrain Design, volumetric efficiency. 1 D cycle simulation, VW Polo 2 valve | Leave a comment

Our new arrival

Posted on January 2, 2012 by Tiger Core

Bought a new car – an old Mercedes Benz “W124″ recently. It’s the 400E model with the 4.2 litre V8. I’m quite familiar with the W124 Mercedes mid size model. A car which replaced the W123 and widely has the reputation of being one of the toughest Mercedes in the business- certainly not built anywhere like this on the W210 and models which followed. It’s a cliche but they certainly don’t build them like this anymore. What I’m not so familiar with is the 275 Bhp 4.2 litre V8 engine which I never had any exposure to when growing up in the UK. They seem reasonably common over here in the USA and certainly reasonably priced. I work with quite a few Germans and have contacts who work or have worked as engineers as Daimler Benz in Stuttgart and they are all unanimous: The W124 was the last of the over engineered cars with alot of money thrown at it’s development and execution that you simply wouldn’t get on a your common garden cars. It’s not unknown for the 4.2 litre V8 (code M119.975) to do 300-400,000 miles without major overhaul- I found many for sale with lots of miles.

Doing my due diligence and researching the car and it’s strengths and weaknesses has been quite interesting. I LOVE doing my homework and ressearching up on well executed pieces of engineering. They really are tough. As you can see from the pictures, despite spending 18 winters in Chicago the bodywork is remarkably rust free. When I still lived in the UK I owned an old 1984 W123 280 TE ‘estate’ or wagen for a brief while and that car was very rusty with rust holes in the sills (rocker panels) and along the arches. I was shocked. And this while only subjected to the relatively mild UK winters. This W124 is not like that at all and I found out recently that the W124 series was NOT galvanised. The ones I see around rarely have much rust. Alot is probably to do with them being garaged here in the US (more so than the UK) but some of the credit must also go to the DESIGN of the W124 relative to the W123. Compare that to a similar period Japanese car-most of which would have dissolved by now.

Inside everything feels solid and the controls have a typical teutonic feel to them. The 722.3 automatic transmission is tall geared mated to a tall 2.24 rear differential ratio. This no doubt should bode well to reasonable fuel economy. So far combined urban and rural driving (with some fairly congested trawls to work) have averaged 15 to 18 mpg(US) or 17 to 20 mpg (UK Imp). The engine compression seems to be high despite having covered 147,000 miles and uses very little oil. The transmissions changes are a bit ‘soft’ and slurry even though the fluid level is fine and the fluid colour is clean but I tackled this by some modest adjustment of the modulating pressure via adjusting a ‘T’ on the side of the transmission. If this doesn’t rectify it I will change the transmission fluid for ‘F’ type fluid and change out the K1 spring and piston assemply for the replacement upgrade when doing this (a relatively easy procedure). Perhaps a transmission rebuild may be on the cards in a few years.

While doing my ‘ressearch’ I found lots of period Mercedes Benz adverts as well as modern ones. I for one love soaking this stuff up so I thought I’d share them with you.

(W123 but still…)

Posted in Automotive | Tagged 400E, Mercedes Benz, W124 | Leave a comment

Car Styling, DNA and “Design Language”

Posted on December 11, 2011 by Tiger Core

Having test driven the 2011 Dodge Charger recently, and appreciated its imposing yet elegant styling, got us thinking a lot about what makes a car styling hit the ‘right spot’. It is, of course, highly subjective. However it’s amazing the common consensus as to which concepts get it right. There seems a fine line as to what feels innately ‘right’ and what looks wrong. It’s what some would call “Taste” or discerning taste. This is highly subjective , of course, but as any psychologist will tell you, this substantiated subjectivism, once explained should show that we’re not in the minority amongst those enthusiasts and conoseurs who appreciate thoroughbreds.

To further elaborate we need to look into the difference between fashion and style. Fashion comes from outside and follows zeitgeist or the spirit of the moment. It is somewhat gimmicky and is subject to social pressures. By it’s definition it will tend to be transitory. A good example of a fashionable car of it’s time is Datsun 120 Y or Nissan Sunny coupe.

An example of a very dated looking design that's 'of its time'

Another example of a fashionable at the time design that's horribly dated now

A fabulous example of a classically styled car (early 70s Manta) that's aged very well indeed

Hyundais embrace rampant consumerism with aplomb. Anything that will spike up sales , their design philosophy is pliable with a non consistent design language and zero DNA

1998 Hyundai Sonata showing gimicky styling and no consistent brand image

A few years later came a newly styled Sonata-with copied elements from contemporary Jaguars

...And then came the "Honda Accord style" of Sonata-shamelessly taking design elements from the market segment it was fight for

Latest Sonata does look suprisingly fresh but with a very contemporary and trendy look...let's see how well this one ages

Style, on the other hand, is almost an innate visceral quality that comes from within. A well styled design is more to do with form , balance and proportion. A well styled car is more likely to be elegant-even in years to come. A dated design can still be a thoroughbred. Typically we’ll call these designs timeless thoroughbreds. . A fashionable design that captures the mood of the moment won’t and is less likely to be timeless. Fashionable design will follow and conform to the mood of the moment. Short termism to be forgotten next season. A styled thoroughbred is likely to stand alone and more likely to become a classic or even an icon. eg 928 porsche, ferrari dino , porsche 911, Jaguar E type. Something to be admired for years to come… like an Omega Seamaster series watch or a Victorian manor house

These days, we live in interesting times: Change for changes sake for the sake of being different- even ugly is valued more than beautiful-and-evolved, by the masses. This is a side effect of rampant consumerism- where a change , something NEW will cause a spike in sales and that’s what’s important to manufacturers (until the next facelift) and the masses are conditioned this way and have adapted. It hasn’t always been this way however. If we wind the clock back to as recently as the 1980s and consider a few facelifts and model upgrades from history. The BMW 3 series went from the much loved E21 series to the wholly re-engineered E30 series 3 series.

The original BMW "E21" 3 series, an evolved clean design

The E30 replacement for the E21 3 series, an evolution of form

Externally- this was definitely evolutionary rather than revolutionary. This was commended. The original E21 3 series sold about 1.61 million where as the E30 sold about 2.2 million over about the same period of time. No one criticized this evolutionary approach. It happened again in the early 1980s with the Volkswagen Golf. The Mark 1 evolved into the Mk 2. The commercial at the time showed the new car emerging out of a chrysalid in it’s newly evolved form. This car got a warm reception and sales of the Mk2 were much higher than the successful Mk1. Compare that to the avant garde Ford Sierra in the UK, which replaced the staid Mk5 Ford Cortina. Initially at least, Ford couldn’t shift enough Sierras and Fords great marketing machine had their work cut out for them trying to re-educate the masses. Typically the premium market segments were even more conservative.

Things have changed however and these are but far flung distant memories. Case in point is the 2004 Jaguar X350 XJ saloon. Styling wise the X350 is an evolution of a long line of Jaguar XJ saloons that follow a low slung sleek look that harks back to the ground breaking car of the late 60s.

Elegant form of the original 1968 Jaguar XJ- a design classic

Subtle evolution of a design classic- the 1975 Jaguar XJ saloon/sedan

Final flower of the XJ saloon/sedans, the series 3- re-penned by Pininfarina

In addition it featured interesting touches infusing more Jaguar DNA and reinforcing the brand- the deletion of the ‘post modern’ C pillar quarterlightaddition it featured interesting touches infusing more Jaguar DNA and reinforcing the brand- the deletion of the ‘post modern’ C pillar quarterlightwindow (that the X300 series inherited from the late 80s XJ40) in favour of a more traditional one that harks back to the series 3s and before, the placement of horizontal cross bars on the grill just like the series 2s, the presence of larger outer headlamps-smaller inner headlamps and the intricately designed rear LED lights that echo the post gothic style of the series 3 rear lights.

Front view of Series 2 XJ showing larger outer headlamps and horizontal and vertial grill bars

2004 Jaguar XJ shows similar grille cues to the 1975 series 2 and bigger outer headlamps

Jaguar Series 3 XJ6 'gothic' rear light style

Jaguar "X350" real lights that hark back to the style of the series 3

The body had considerably more girth but these details would have delighted aficionados of old. Engineering wise the X350 was very advanced with air suspension, light weight aluminium monocoque construction. The bare body shell is lighter than a Mini of the same vintage. The cars fuel economy, driving dynamics, and performance trounced the rivals from BMW and Mercedes. Despite all of this the car didn’t sell up to expectations. The mainstream market place today, even the premium market place probably barely noticed the heritage features I outlined above. They fell upon closed eyes. All they saw was a car that looked dated and it was an image they didn’t associate with. The X351 which replaced the X350, is radically different from a styling point of view but not very different from an engineering point of view. Even during the recession this car has sold beyond expectations and the response has been massive.

A few years earlier Chris Bangle at BMW did similar if not more radical things. He broke the classic understated and balanced, tasteful lines of which BMW had developed for generations for a intentionally contravercial and ugly lines of the BMW E60 and E65 5 and 7 series of the time.

E32 BMW 7 series

E38 BMW 7 series

E39 BMW 5 series

E65 "Bangle" 7 series

E60 "Bangle" 5 series

At the time many deemed him a Salvadore Dally like nut job but in retrospect with what was said about Jaguars experience perhaps he was more plugged into the Zeitgeist fashion of the time. The sales of BMW did not suffer but this could have been more to do with the almost fanatical following they had developed on the basis of their driver focused engineering ethos

Going back to the style vs fashion discussion- we’re firmly in the style/classic camp over fashion here. This site is designed to appeal to individuals with discerning taste who appreciate the engineering behind a great car, afterall. A good design shouldn’t have to grow on you, or be explained- the way styling pre-madonnas seem to have to these days, a good thoroughbred design is appreciated almost immediately on first negotiation of its form. There shouldn’t be thought and contemplation involved in this process. You instinctively know when something looks beautiful. This is a product of your upbringing and appreciating forms both aggressive and gentle in nature and all around. Chris Bangle might disagree but he would go to great lengths explaining why and how his flame surfacing works. The BMW faithful would nod like nodding dogs before trotting off trying to convince the non believers. However from our stand point if the stylist has to go to great lengths to explain a cars beauty to try to convince people we deem it a failure.

Of course those that argue that sales numbers and popularity alone paint the way of what endures would be well advised to remember the motto “Popularity is merely the hallmark of mediocrity”. This is also perhaps the best cautionary when contemplating capitalism that’s gone too far towards consumerism and what it means to the end product and the choice of the INDIVIDUAL but this is a discussion for another time.

Brand identity and DNA are like a currency or investment you build up. Good examples are the Porsche 911, the Chevrolet Corvette , Volkswagen Golf and architypical Jaguar XJ. So much so with Porsche that the stylistically similar Porsche Boxster and Cayman are instantly recognisable as a Porsche because it adopts its design elements. Unfortunately these design elements dont work in an SUV such as the Cayenne- however Porsche got their fingers burned with the 924/944/928 series and have stayed conservative ever since. Lexus afficionados probably won’t understand what I’m getting at- herritage, DNA and brand identity. It’s something thats intangible but if you don’t have it or you dilute it using common platform engineering where the engineering pedigree and elegance doesn’t back up the product (good examples of this are the mk 1 Audi TT and the Jaguar X type -which was a good car but could have been soo much better) then something is amiss. It’s this kind of investment that takes years or even decades to nurture.

Form vs function

The other angle in the fashion vs style debate that should be mentioned is form vs function. However the car looks function must be considered in their somewhere. When I was younger I believed function always followed over form, but as I matured I realised it rarely is ever totally the case.
Even with something as bland and boring looking as a late 80s/early 90s Audi or a Toyota Prius.
If you did design a car purely with function in mind- aerodynamics would take a priority with a small frontal area and good cross wind stability, with the vehicles centre of pressure located behind the vehicles centre of gravity. There grill between the headlights would probably go: Cars such as the X300 Jaguar for instance utilise most of the cooling air from the vents in the bumper- the chrome radiator grill is there mainly for decorative purposes. You could in theory replace the grill area with somee kind of air duct or faring to produce more down force. Quite often open grills in the traditional place merely cause air to enter the engine bay and cause buffeting and therefore reduce the cars CD. It is for this reason cars like the Mk2 Golf have the grill blocked off on one side on the inside.
The headlights could be a strip of innane but functional LEDs and the car would have a high notch back rear end that tapers or a kam tail if it’s a fast back.
The target Cd number could be 0.26 with a rounded snub nose.
HOWEVER I think such a car would look boring and very very bland.
There comes a point in most of our lives, even engineers, where a certain amount of emotional intelligence is gained. Like it or not there is an artistic aspect to car design and what appeals to us. This is why there is nearly always a balance of form over function. I think this is needed or else sales are effected. Even with the constraints of aesthetics alot of the functional criteria can still be met: The Mercedes W124 series looked very ‘mercedes like’ with the classic grill (kudos to stylist and design lead Bruno Sacco) however it was one of the most aerodynamic cars in it’s class (Cd=0.28-0.30) and the same with the Mk2 Golf (0.34) compare that with the original “Jellymold” Ford Sierra which was less aerodynamic than both and had side wind stability problems but LOOKED more functional.

Ford Sierra of 1982 was avant garde and often nicknamed the Jellymold

Volkswagen Golf Mk 2 is from the same era with the same aerodynamic drag coefficient but practicing detail optimisation design rather than whole sale rethinking

The midsize Mercedes W124- another example of period German detail optimisation, (superb aerodynamics) evolution and understatement without resorting to radical styling

I for one, am glad of this form vs function balance. It’s what keeps cars objects of passion and desire and stops them from becoming A to B appliances (although the current regime of disposable car culture and functional hybrid type cars are doing a very good job of reversing this).

So in summary when we contemplate Jaguar, series 1, series 2 ,series 3, and X300s we salute the likes of Geoff Lawson and Sir William Lyons in a world where subtley and class still hold value however when we think of Ian Callums work on the X351 where he eagerly ‘made his mark’ we can’t help but lament the passing of a great styling era. We understand why it needed to be done to shift sales numbers- there’s no arguing with that but perhaps we’re out of touch with the fast changing whimsical world around us. The same can be said about classic era shark nosed BMWs compared to Bangle era flame surfaced abominations. In our view Paul Bracq could teach Chris Bangle so much as could the late great Geoff Lawson to Ian Callum.

This blog is in danger of becoming a ‘they dont design them like they used to’ or of the vein ‘ when I were younger- things were alot better’- so to prevent this- we cite modern non retro cars as agreeable: the new Dodge charger as good looking, the Alfa 147 and 8C new Maserati Quattroporte and Maserati Granturismo (a deliciously gorgeous car!), the last Chrysler 300C, (definately not the latest 300!), Audi R8, Aston Martins, Mcclaren MP4

And to further illustrate that we don’t go googley eyed over anything and everything retro we think the New Mini definately gets it wrong on so many levels: its retro but in a vulgar and inelegant OTT and contrived way lacking any of the charm of the 1959 original , however it’s a lifestyle fashion item- which further confuses the Jaguar classical vs modern dillemma- as it is a sales winner!

So, to leave you with some parting thoughts: Some years ago Ford identified that it’s brand Lincoln needed an image and styling change: It’s traditional Lincoln customers were old with an average age of approaching 60 and this whole demograph was apparently “dying out”. This is why more performance orientated youthful cars like the rear wheel drive Lincoln LS series was introduced to try to capture a new market demograph. The question is- does a whole old demograph die out? What happens to 65-70 year old Grand pa and Grandma Smith who drive their Buick Roadmaster or Lincoln Towncar? Do they really die out? But generations are living longer now. So if this theory is true what will the next set of 65-80 year olds graduate to? Won’t they also grow into similar tastes of the generation they replace or will they don their Chrysler 300s and Pontiac G8s for Cadillac CTSs holding everyone up on rural roads at 33 mph?

Even if you don’t agree with us I hope this blog entry has given you some food for thought. So next time you find yourself wanting to love the styling of something sure that it will grow on you- ask yourself should it have to?

Posted in Automotive | Tagged BMW, Brunno Sacco, Chris Bangle, Ford Sierra, Geoff Lawson, Ian Callum, Jaguar, Jaguar X350, Mercedes Benz, Paul Bracq, W124 | Leave a comment

Test Drive 2011 Dodge Charger with 3.6 litre pentastar V6

Posted on October 16, 2011 by Tiger Core

It was with interest that we picked up the keys of the 2011 Dodge Charger V6. Everything depends on ones expectations and in the past, from an enthusiast perspective at least, we’ve come away less than impressed by modern American car offerings…until now. Little did we know how impressed we would come away with this full size 292 Bhp American Muscle car. So much so that we thought it warranted a road test review/write up. And this is what we found:

The lightly but effectively reworked 2011 Dodge Charger

Ride and Handling: Well judged! The 2011 LX platform Charger V6 is a big and heavy car at 3961 lbs. Behind the wheel the car doesn’t feel that big and unwieldy. For a base model the car rolls little around corners and the suspension absorbs the savage imperfections of Michigan roads well (I wonder how much that would change with the larger 19-inch wheels with P235/55R19 option of the bigger brothers). The maximum grip capability of the all-new Dodge Charger now holds close to 0.90 g cornering G. This improved road-holding is in part due to the more aggressive front- and rear-camber geometry. Set at -1.0 degrees in the front and -1.75 degrees in the rear. The Charger is set up for high-speed cornering following classic increase in negative camber to do so. In addition there are retuned monotube shock absorbers augmented by the use of premium hydrobushings, retuned spring rates and redesigned front and rear multi-link suspension geometries that improve ride/handling compromise.

The steering is pleasantly direct and responsive and reasonably weighted for a saloon. The system is 25% quicker than the previous Charger. I was suprised to find out that an all-new electro-hydraulic power steering (EHPS) system that reduces steering noise and fuel consumption. A little while ago when Richard Parry Jones the handling Guru from Ford mandated that Ford wouldn’t go to an EHPS system as ride and handling was one of their core marque values of their products and they wouldn’t compromise this in the interests of fuel economy or package. I’ve certainly driven modern BMWs and Jaguars with conventional hydraulic systems that exhibit more on centre vagueness and leave you feeling more disconnected from the road. This is not too much of a suprise really as on Teutonic Autobahn stormers (modern Porsche 911s included) on centre feel/responsiveness makes a car feel nervous at high speed. This is why on these high speed cruisers off-centre gain is a higher priority combined with slow on-centre gain.

Traction control is not too intrusive and kicks in right at the cusp of loss of adhesion. It is just right in the dry but could do with being a tad more moderating in the wet. The brakes are somewhat over servoed for enthusiast tastes.

Total Vehicle Styling/ Body / Interior: The exterior style of the car is imposing and captures enough cues to nod back to the 1968 original without being engorged in contrived retro heritage. This is what we like to see: A modern American car that doesn’t shy away from an aggressive stance and an individual look. Too many modern American cars have forgotten this and instead aim to dilute the bold imposing American style in favour of an inoffensively bland ‘Japanese-like’ contemporary look. Aiming for the lowest common denominator to get maximum number of sales from the masses invariably produces a car that’s liked by all with less appeal for the individualistic driving enthusiast. Just look at the opposite corner in the Ford stable and the excrutiatingly boring looking Ford Taurus. Or the Chevy Impala. To our eyes the Charger looks fresh.

The last generation Charger tried too hard to be aggressive, with its exagerated coke-bottle hips that just jutted up too abruptly to the rear side windows that just looked plain awkward. There’s certainly a fine balance between looking individualistic and imposing and just looking OTT. A 1970s Mercury Cougar adorned with an abundance of chrome and hideaway headlights is the later as was the last generation Charger. This generation Charger gets closer to a good balance.

The interior of the Gen 2 Charger is a quantum leap over its predecessor. We have it on good authority that Fiat in Italy had a hand in the development of the interior style and it shows. The use of Fiat as interior design consultants seem to be Chrsyler-Fiat groups new global corporate strategy. The use of soft touch plastics to replace expanses of cheap plastic of the previous generation car which have been banished. The onboard trip computer is reasonably easy to use but our mpg meter was optimistic by about 6%

The seats are supportive and comfortable and didn’t make my bottom ache the way a Nissan Altima did recently on a long trip. A colleague of mine critisized the choice of seat fabrics. He, however is an Acura fan, and it’s perhaps unfair to compare an entry level Charger with his top of the line Acura.

Some aspects are appear cheap: the automatic shifter lever plastic slot cover I also dislike the way the indicator stalks follow BMWs stupid lead -indicating when moved slightly with no way to cancel. Stupid!

NVH/refinement/calibration of vehicle: The idle of this car is super smooth and the cabin is well isolated from the engine. The engine is a 60 degree V6 and therefore inherently exhibits some second order vibration but this is not evident at idle.

The transmission and throttle pedal are well calibrated. The pedal ( a virtual pedal with no mechanical linkage- this being a modern torque based calibration) is moderately damped. It’s certainly not been calibrated with the eagerness of a sporting saloon such as a BMW but it’s also not as annoyingly conservative as a Jaguar. We’ve seen alot of criticism directed at the 5 speed Mercedes based NAG-1 transmission but we find that for this entry level V6 the transmission responses to be well judged and calibrated in.

When the engine is revved throughout the rev range it gets boomy at around 4800 -5000 rpm which then subsides again as you head towards 6500 rpm. This is obviously a resonance. I don’t think it’s the engine- but more likely particular to this Charger application: Some component is being excited and is vibrating (The Challenger V6 we also tested didn’t exhibit this but both Chargers we tested did). It’s no big deal and it’s only because some of us ourselves have been involved within the industry in NVH refinement that we notice it, but it is unfortunate as this engine is certainly at its best, from a power delivery stand point, at the higher end of the rev range.

The engines noise level is subdued and leads to a pleasant driving experience- especially when cruising long distance. In terms of sound quality however, this engine is no jewel. It neither has the sibilant hum of a vintage BMW straight six at low end or its snarl at top end or the classic Alfa Romeo V6 wail. It will be interesting to see what Alfa Romeo do to this engine when they adopt it for their application. Also to be fair, I cant imagine a Chrsyler group product with a cultured European snarl or wail but they do need to develop their own signature sound that is different to their bigger Hemi V8s if they are to combat the myriad of characterless sedans from Japan and Korea.

As it is the engine only barely sounds like a V6 (more like a 4 cylinder) at lower engine speeds which leads me to wonder whether the V6s natural 3rd order has been subdued and the 2nd order noise is more apparent.

Engine / drive train: It’s wise to bare in mind that the dual vvt 3.6 litre V6 has to cart around nearly 4000 lbs of LX platformed vehicle around. It should come as little suprise therefore that the quoted 0-60mph in 7.3 feels more like mid 8s. The engine is definitely better at top end where the tachometer needly just races around the gauge. The performance is on the warm side of adequate rather than rapid. To be expected and quite satisfactory considering the application. No doubt the weight and tall gearing come into play here. Rarely can you have your cake and eat it too. The new 3.6 litre Pentastar V6 (known internally as the Phoenix engine) features intake and exhaust independent Variable Cam phasing and produces 292 Bhp at 6400 rpm and 260 lb ft (12.3 bar BMEP) at 4800 rpm (90% of the peak engine torque is available from 1600 to 6400 rpm). The cam phasers are the Borg and Warner units that are cam torque actuated (first seen on the Jaguar 5 litre AJ133) for better response and lower oil pressure requirement. Running a compression ratio of 10.2:1 the engine utilises all aluminium construction (the block is about 20 lbs lighter than the equivalent GM V6). Interestingly, the engine featured integrated exhaust manifolds into the cylinder heads, which use engine coolant to get quicker catalyst light off and reduce over fueling when the catalysts reach their peak temperature limits. This release does not feature GDi yet. This is just the kind of engine that the Chrysler group needed. In the early 1990s the very expensive port throttled 3.6 litre BMW Inline six cylinder ‘M’ unit produced a similar power output without the torque spread or peak BMEP of this engine with alot of expense. This is progress, especially seeing as this engine will be churned out at 400,000 a year from the Saltillo engine plant. With the release of the fantastic Ford “Coyote” 5 litre 412 Bhp V8- it’s nice to see a real golden age of American engines.

Without a doubt the most impressive thing about the 2011 Dodge Charger with Pentastar V6 is it’s fuel economy. We attained the following fuel economy (in US mpg):

22.5-23 mpg in medium traffic

even in heavy traffic it rarely dropped below 21 mpg

33-35 mpg at constant 65 mph

30-32 mpg at constant 70 mph

28-30 mpg at constant 80 mph

and even above 80 mph the mpg didn’t drop below 28 mpg. These figures were measured via continual brim to brim fill ups over two specimen vehicles and represent a two way average over a road course on a flat road. These figures are outstanding to us and beat a comparable Malibu 2 and 2.2 litre 4 cylinder. One wonders why the rest of the industry are pushing us buyers towards 4 cylinders engines (especially the Japanese) which can’t achieve the fuel economy or power and torque of this engine in lighter vehicles!

Summary: In Summary this car gets a thumbs up from us. We really expected coming away feeling short and inadequate relative to the V8 models but this wasn’t the case at all. It is a rear wheel drive enthusiasts sedan/saloon with an unmistakable American muscle car look. The interior is well detailed and a fine place to be, the performance is adequate, while the fuel economy for the size of car is outstanding and quite frankly, exactly what Chrysler needed. The lines are flowing and it’s a much prettier car than it’s predecessor, to our eyes. The ride and handling compromise are superb as is the steering. In this market the only rivals are boring Japanese utilitarian sedans for the conformist non enthusiast or corporate common platform yawn wagons from Ford or GM.

Posted in Automotive, Uncategorized | Tagged 2011 Charger, Chrysler, Dodge, Muscle Car, Pentastar, Phoenix | Leave a comment

1998-2003 Jaguar X308 XJ8(R)- An under rated scorching luxury Saloon

Posted on August 28, 2011 by Tiger Core

Understated Elegance Combined With Scorching Performance

The Jaguar X308 XJR is a fabulous under rated machine and should go down in automotive history as a thoroughbred. The truth is that it probably won’t and will fall into the same chasm resided by It’s predessor the XJR (6 cylinder) where values plummet . There is no balanced appreciation in this fical world but so much the better for us enthusiasts. The truth is that this has got to be one of the most under rated saloons of recent times. I have much experience with these from the late 90s
The X308 combines a timelessly beautiful low slung body style with a very efficient and characterful V8. The suspension carried over development advances from the then recently launched X100/XK8 coupe. The structure is from the XJ40 of the 1980s. This is no bad thing: The XJ40 conceived in the late seventies/early eighties and was designed to meet the impending US 40 mph offset crash regulations which never materialised. At the time Jaguar had spent too much developing the hefty XJ40 structure to reoptimise for a lighter structure (the way the contemporary BMW E32 Seven series was). The fortunate upshot of all this as regards the X308 XJ is that it has a very robust structure. According to the UK Department for Transport’s road accident statistics which shows risk of injuries to car drivers involved in two-car accidents on a model-by-model basis whenever an injury is reported, the X300/X308 series Jaguars were among the safest cars on UK roads (measured in terms of chance of death in an accident over a four year assessment period) – three times safer than the safest Volvo models and matched only by the contemporary Mercedes-Benz S-Class. This publication presented estimates of the risk of driver injury in popular models of car, if they are involved in a two car injury accident. It does not address issues of primary safety and gives no information on whether or not specific makes of car have different risks of being involved in an accident. The statistics were based on personal injury road accident data reported to the Department for Transport by police forces within the United Kingdom.

The proportions of the car are wonderfully balanced. In true Jaguar tradition this style of saloon is form over function, as low as most coupes (if not lower than todays over bloated current crop), wide, with an imposing front but without being vulgar and the trade mark tapering rear end. Understated and very fluid.

Low, Lithe elegant yet agressive lines

Outside there is subtle dechroming but just enough bright work to compliment and highlight the svelte lines. It was this style of Jaguar that lead to a Milanese panel of experts voting it LAutomobile piu Bella del Mondo or The Most Beautiful Car In The World, surely a testament to its stylist, the late Geoff Lawson. It was the first year that this accolade was awarded to a non- Italian automobile. Compared to the contemporary German and Japanese opposition the X300 of this era are certainly form-over-function except that with the arrival of the X308 that a very efficient, light weight power plant mated to the superbly refined and robust Mercedes Automatic gearbox (WA580)and especially with the fitment of the R1 option Brembo 355 mm brake discs with 4 pot calipers- the function part of that equation was balanced up nicely.

Fluid rear tapering tail

The X308 XJ series was the last of the Jaguar saloons to be built at Jaguars famous Browns lane plant (the subsequent X350 model was made at Castle Bromitch).
A modern car of immense character the X308 is the ultimate blend of old and new. Not unlike the legendary Porsche 993 series 911s in this way.

Technical Focus

The engine is up to the minute of lightweight (200 kgs dry weight) construction with low overall engine friction with 32 valves of direct acting bucket design and good flowing ports facilitating its high revving capability .The big valves (representing 42% of the bore size) formed part of lightest in class direct acting valve train.
The crankshaft is supported by a bedplate which anchors the mainbearings together and adds rigidity to the bottom end. The cast aluminium bedplate used iron inserts to control bearing sizes tightly-as required for tight oil pressure cpntrol demanded by the variable cam phaser units. The crankcase is split and sealed together with RTV. Like BMWs of this era the earlier versions of this engine featured a parent metal bore that was nicasil coated. This was replaced with iron liners in 2000 after a spate of prematurely worn engines that exhibited excessive bore wear showed up in certain regions where there was high sulphur content in the fuel.
Fuel injection is by Nippon Denso, drive by wire electronic throttle with variable cam phasing and an 5th Generation M112 Eaton supercharger on the “R” variants. The idle speed control not only uses the throttle to moderate the idle speed but a patented method of using the ignition timing as a short term strategy- where by the instantaneous acceleration of the crankshaft is monitored continuously and the ignition timing is moderated accordingly. The AJ27 cars (post 2000 model year) had air shrouded injectors for better fuel atomization. When first launched the AJ26 V8 must have sent shivers down the spines of the rival counterparts at Stuttgart and Munich. The valve train featured direct acting mechanical buckets (something of a Jaguar tradition)– with the lightest valve system mass in its class at 100 grams (including valve , spring collette etc) which in turn allowed aggressive valve accelerations. It was decided to not go with hydraulic valve lash compensation – trials showed that even after well after 110,000 miles the valve lash was well within specifications-such was the tribological pairing of cam lobe to tappet materials and the quality of modern lubricants. If you compared this to the contemporary BMW M62 of the time- which had hydraulic tappets – a fairly sizeable heavy tappet mass reciprocating. This is clearly shown when you analyse the valve lift profiles of the BMW V8 and Jag V8 with the Jag pushing valve accelerations of 0.027 mm/deg^2 and the BMW at 0.020 mm.deg^2. In addition that Bavarian V8 engine had yet to attain variable cam phasing and made a lot less specific output in terms of both power and BMEP. As for the twin plug 3 valve per cylinder Mercedes engines of the same era- well they were certainly very lightweight but had a slow burn rate, were quite knock limited at full load at quite moderate BMEPs and had poor specific output, BMEP and no variable cam phasing. Although it must be said of the Merc that it is capable of running quite diluted charges without misfire thanks to its twin plug configuration and the cylinder deactivation system was both innovative and interesting.
The XJRs overall engine air flow level is around 1100 kg/hr- the intake manifold depression or intake losses are around 115 mbar with an exhaust back pressure of about 750 m bars at peak power. These losses are ok for a supercharged car but there is a lot of room for improvement

Driving Impressions

Suspended by double wishbones all round, the rear suspension system a direct evolution of a concept that can trace its lineage back to the 1960s but optimized and brought up to date.
The XJR steering is only 2.8 turns lock to lock. It is direct but very lightly weighted- a bit too light for our tastes. It could also do with a bit more castor or steering self centering. The ride is pleasantly soft for a boulevard cruiser although there is a bit too much roll for a sporting car in the ‘R’ variants. The US spec cars indeed have different springs and dampers. In the US spec cars when sliding the rear end it is possible to get the car caught in series of tail slides initiated by the roll induced lurch of this great ship. The secondary ride is a bit harsh due to the low profile tyres. Overall the suspension is well judged for the market it was intended and indeed the low speed ride is glorious compared to the jittery air suspended X350 which followed. Around the skid pan contemporary road tests attained 0.87 to 0.88g cornering force before terminal understeer ensued. This is a great figure for such a colossal saloon and similar to a Mid nineties Porsche 928 GTS.

The car is exquisitely refined- even compared to the model that followed. It’s no secret that the noise transfer functions changed a great deal with the aluminium construction and a HUGE priority was put on the X350 to get that car to be less boomy nevermind matching the serenity of its predecessor. The performance is scorchingly quick with the 0-60 mph dash taking about 5.3 seconds and a standing quarter mile passed at high 13s. It’s relatively cheap to make modifications to the XJR powertrain to get a lot more power. The supercharger is only driven at 2:1 drive ratio and the peak engine revs are 6150 rpm (the naturally aspirated engine revs to 6800 rpm). Eaton says the M112 has a peak rotational speed of 14000 rpm- which means there is some room to increase pulley ratios for more power if you’re willing to change the supercharger drive belt more often.

The interior is still something of a cosy gentlemans club with lashings of walnut veneer and leather. However the seats offer good lateral support and are no armchairs. The deep pod instruments take some getting used to but after all this time have become something of a signature of the X308 XJ series along with the rest of the ‘spitfire profiled’ wood veneer. It’s often cited that the X308 is cramped and these musings are vastly exaggerated. I’ve heard folks liken the interior room to that of a sub compact. I guess it depends on your frame of reference. I’d rather have the interior room of the X300 series –which is more than adequate for a small family-and the gorgeous silhouette that goes with it than more room and a non descript and non distinctive testimony to ubiquitous conformity.

Dissapointments and what would we have done better? Well I think it’s a poor showing that the secondary chain tensioners on these cars took Jaguar 3 design iterations to get right. You should be ok if you purchase a 2001 model year or later. I wouldn’t let it dissuade me from buying a good condition one- just make sure you upgrade to the latest secondary chain tensioner. The aforementioned pulley ratio change would be a worthwhile modification, while focusing on the airbox- perhaps using one from a later 4.2 litre XKR with additional orafice- will help to de-restrict the supercharger. The exhaust systems 750 m bar back pressure could be reduced with larger sectioned tubing and larger silencers (if noise levels want to be retained at their current level). There is no decent system on the after market today that attains a reasonable back pressure of around 500 mbars or less unfortunately. All we see are an array of overpriced overhyped branded systems from Jaguar “boutiques” trying to exploit discerning customers for top dollar.
In addition I think it was poor judgement on Jaguars part to drop the limited slip differential of the previous series (or powerlock) and the safety factors and strength of the fitted 14 HU differentials of the X308 are low and no where near as strong as the legendary 15 HU and 4HU units fitted to previous generation cars and enjoyed by many hot rodders. As a result on the R supercharged cars, you may get lucky and have no problem or you may have big problems with the crownwheel /pinion teeth sheering off.
Bring this chariot up to date: we would love a 550-600 Bhp TVS1900/2300 Eaton supercharged beast, with 15 HU differential, powerlock, a modest capacity increase to 4.6- 4.8 litres and the Mercedes gearbox tuned to be a tad more responsive

Posted in Automotive | Tagged AJ26, AJ27, AJV8, Browns Lane, Eaton M112, Jaguar, Jaguar XJ8, Supercharger, X300, X308, XJR | Leave a comment

So Long S2000 (Gone but Never Forgotten)

Posted on May 4, 2011 by Tiger Core

The last Honda S2000 rolled off the production lines in June of 2009. In Europe Honda commemorated this occasion with the S2000 Ultimate edition. These last of the line Ultimates feature Grand Prix white paintwork and snazzy looking dark graphite grey alloys. In a statement the company said that the white paintwork is supposed to be remiscent of the color first used by Honda in 1964 in their F1 as well as many sporting models since. To complement this exterior treatment this car will get red leather interior along with numbered plaques on the metal sill plates and dashboard.

The S2000 was launched in mid 1999 and represented an uncompromising two seater sports car. The drive is to the rear wheels like a proper sports car and the stiff X bone chassis was bespoke, unlike common platform contemporaries like the Audi TT. It carried on the illustrious line of 1960s Honda S500, S600 and S800 roadsters which were quite unique in their time. Like the S2000 the S roadsters of the 1960s were named for their engine capacities and shared the exciting high rpm character of their successors, the last one of which (the S800) rolled off the production lines in 1970. With cars getting ever heavier and heavier, sharing more and more components with their mundane sedan bretheren it is always refreshing to see uncompromised raw cars like this and the Lotus Elise make an appearance in the market place.
Honda S2000 rear side view

The S2000 is powered by Hondas F20C and F22C1 engines, the only engines in the Hondas armory designed to fit longitudinally. It represents the highest specific naturally aspirated power unit for a regular production car at 120 Bhp/liter. The BMEP or torque per liter is highly respectable rather than outstanding (like the M engines from BMW or the GT3 engine from Porsche). The US market got a 2.2 liter engine from 2004 onwards, as did the Japanese market after 2005 while the UK, Europe and Australia soldiered on with the 2 liter motor.

Technical Focus

Undoubtably the center piece of the Honda S2000 is its engine.

Honda S2000 view of the engine

The F20C is a 2 liter inline 4 cylinder engine DOHC 16 valve engine equipped with Hondas Variable Valve Timing and Lift Electronic Control System or VTEC. This is not merely a variable camshaft phasing system but a system that switches between two profiles and thus varies duration, lift and phasing also. The tuned length exhaust manifold consists of a four into two into one system or tri ‘Y’ system with about 300 mm primary lengths and 400 mm secondary lengths.

Despite the cars tremendous 9000 rpm range it does not use balancer shafts. The valve train is driven by a ‘silent chain’ to an intermediate pulley which in turn drives the cam sprockets by a helical gear wheel. This is a nice compact arrangement and not dissimilar to the first generation Lexus IS200 straight six.

S2000 compact cam drive- gear driven intake to exhaust cam

The engine was rated to meet Euro 3 emissions standards and LEV-2 here in the US. Although the catalytic converter is located quite far back (about 1 meter from the exhaust valves) which isn’t conducive to fast catalytic converter light off times (bad for emissions) the use of exhaust secondary air injection and catalytic converters with metallic substrates no doubt helps. Kudos to Honda for going to the expense. No doubt the use of secondary air injection into the exhaust ports has helped meet emissions also.

The car achieves its stunning high rpm power through a combination of excellent flowing ports

-Flow tests show a peak Alpha K flow value of almost 0.3- an outstanding figure

- long cam duration (afforded by the VTEC system) – the longer ‘power profile’ duration of 336 degrees (@ top of ramps) and even a shorter profile of 264 degrees.

-a low back pressure exhaust of about 350 mbar at peak power and low intake losses (less than 30 mbar). Looking at the airbox it’s evident that careful attention was put into its volume and design detail to attain these low losses.

-and a high compression ratio of 11:1 (11.7:1 for the Japanese market) via a finely optimized combustion system.

The finely optimized combustion system includes inlet ports that not only flow outstandingly well but also induce a lot of inlet charge tumble motion. This contributes to a fast burn (good for catalyst light off/emissions, better for knock resistance and fuel economy through EGR tolerance). The inlet ports are only partially machined nearer the valve seats and not totally machined (as in something like an S54 BMW M3 or a Valvetronic 330i). Ultimately the engine doesn’t have the fastest burn in the industry (10-90% burn duration at peak power of 19 degrees crank angle) but the engine has exhibited extreme lean running capability in laboratory conditions (Up to Lambda 1.45 before HCs shoot up!)

S2000 outstanding Flow relative to bore

null

The engine is reasonably lightweight, with a combined dry component mass (to DIN 72000) of just over 140 kgs.

The cylinder block uses fiber-reinforced metal, where the cylinder cores are made up of a combination of aluminum oxide and carbon fibers. During the casting process when the metal is molten these cores absorb some of the aluminum. Then the block is cooled and the cores bored out, leaving behind a cylinder wall sleeve, about 0.5mm thick, of aluminum reinforced with this aluminum oxide and carbon fibers. Like the Hypereutectic Reynolds 390 process used on Porsche 928 v8s and Mercedes V8s this is very tough and durable and should theoretically show a reduction in friction. This process apparently allows closer cylinder to cylinder distance or, more precisely, bridge distance between bores: in this case the F20C engine has 94 mm bore centers (so therefore a 7mm bridge distance). BMW has used closer distances of 4 mms on the cast iron M3 blocks and their parent metal aluminum M5 V8 blocks but both of these were of siamesed design. The Honda is of open deck cylinder block design with coolant between each cylinder. Honda first used this process in its NSX supercar. The piston skirts are molybdenum disulphide coated to work in conjunction with the above material forming a favourable tribological pair to reduce friction. Roller bearing cam followers continue Hondas emphasis on low friction. The pistons are of forged aluminum alloy (very rare in its contemporaries) while the crankshaft is of heat treated forged steel.

The F20C engine makes 240 Bhp at 8300 rpm and 153 ft.lbf (208 Nm) at 7500rpm

While the Japanese market model with with it’s higher 11.7:1 Compression ratio makes 247 Bhp at 8600 rpm and 161 ft lbf at 7500 rpm.

The above outlines the engine for the original AP1 release. The AP2 release for the North American market also included larger version of the F20C. Designated F22C1, the engine’s stroke was lengthened (from 84.4 to 90.7mm, increasing its displacement to 2,157 cc (132 cu in). In order to maintain the same peak mean piston velocity of 25 m/s the redline was reduced from 8,800 rpm to 8,000 rpm with a cutout at 8,200 rpm instead of 9000 rpm. Overall the torque increased between 4 to 10% . Peak torque increased 6% to 162 ft·lbf (220 N·m) at 6,500 rpm while power output was the same 240 Bhp (179 kW) at a lower 7,800 rpm. The F22C1 was used exclusively in the North American market for 2004-2009 models however it was introduced to the Japanese market from 2005 onwards, with the F20C being used in all other markets. On paper at least it would seem the best and purset of powerplants would be a high compression ratio Japanese market engine (with the resulting slightly higher torque but still with the smoothness and ‘revviness’ of the smaller capacity/shorter stroke. Unfortunately in the USA with it’s 91 octane (RON + MON /2) fuel this is unlikely to be practical on an engine that is ALREADY knock limited at peak power speed.

In conjunction with its introduction of the larger capacity F22C1, Honda also changed the transmission gear ratios by shortening the first five gears by about 1 to 4% and making the last one 2% taller for better cruising, and replaced the dual and triple cone brass synchronizers with carbon single cone for lower friction. The power is transmitted to the rear wheels via a Torsen differential. In addition the brass triple cone syncronisers were replaced with double carbon single cone and single carbon cone synchronizers. In theory the carbon synchronizers improve the gearchange feel. However we’ve found the improvement in shift quality, to what was already a very slick change, minimal. Vehicle performance theory 101 tells us that wider ratios benefit performance and fuel economy overall while closer ratios benefit driveability and are usually favoured immensely by the all out driving enthusiast.

Structure

The structure of the car uses what Honda calls the High X bone frame. Being a roadster rigidity is of utmost importance. The X bone structure consists of a box section central portion where the rear diagonal members attach to a transverse rail while the front diagonal members meet the longitudinal side members and where the rear of the engine is supported. This tunnel serves as the backbone and main load-bearing structure for the vehicle, as well as housing the transmission and driveshaft.

The body has moderately high side sills which in tandem with diagonal (X) bracing on the front and rear subframes , providing additional rigidity. Suspension and drive loads from the wheels are fed directly into rigid subframes at the front and rear which in turn transmit their forces into the main structure.

High strength X braced backbone chassis

The windscreen frame is reinforced via a tubular section brace and a roll over hoop adds internal strengthening by being fixed rigidly to the chasis.

The front and side chassis members consist of straight sections (not curved) made of high tensile steel. There are deep side sills connecting to the front transverse rails at the same points as the centre tunnel X-bone arms. The Side sills are deep but still not as deep as the X bone Center tunnel so as to facilitate entry and exit of the car.

A side floor member runs back from here to the rear transverse rail which is part of a rear transverse frame. The result is a strong passenger cell. This is helped by a cross member in the passenger cell which distributes energy to the central tunnel in the case of a side impact. Passengers may notice this as there is a pronounced well in the cabin floor ahead of it.

The Sum total effect of all these measures is, according to Honda, is to have the torsional rigidity of a coupe and the bending stiffness that’s better than either a coupe or a convertible.

For 2004 model year (with the introduction of the F22C1 2.2 litre engine) The structure of the car itself was stiffened with new gusseting at the front crossmember joints, some additional fixing points for the stiffening rod at the rear for better location and additional reinforcement of the rear wheel arch bulkheads. The front suspension has been more precisely constrained with new brackets for the upper control arms.

Impressions

null

The S2000 CR was the most focused version of the S2000 launched in the USA. “CR” stands for club racer. There is no stereo, air-conditioning or a roof. In addition sound deadening material has been deleted. Countering this the CR adds some aerodynamic body addenda , body strengthening and wider rear tires. Honda quotes the CR weight as 2,765 pounds (1254 kgs) — only 99 pounds lighter than the standard ’08 S2000. Once the standard aluminum hardtop is in place and the CR’s curb weight goes up further to 2,813 pounds (1276 kgs). Frankly the pairing down of this already sporty model to further intensify the driving experience is something that we welcome. If you want a softer edged “sports car” the market place is littered with fitting alternatives. With customers ‘needs’ driving cars to be ever heavier and focused on cup holders and MP3 playing, I-pod compatible hands free dialing mobile offices this is refreshing. Although I prefer the shrill 3^rd order wail offered by a 6 cylinder, a high revving V Tec 4 cylinder with mammoth cam duration and a free breathing exhaust system is a unique and spirited alternative and certainly beats the usual muted whiny eco motors of every day snooze wagons. The engine is very smooth for a four cylinder (with it’s usual out of balance 2nd order couple) which is all the more remarkable when you consider that it has no balance shaft. It’s a tribute to Hondas technically gifted engineers who’ve managed to keep the reciprocating masses low enough as not to intrude into the harsh NVH region at the right cost and durability level. It is true however that the lack of sound insulation admits a lot of high frequency ‘tinny’ noise into the cabin.

On the road the S2000 has a precise but firm gear change. With the original S2000 the steering is superbly direct (but could do with a tad more feel- perhaps a small failing inherent to the use of electrically powered steering). The earlier 2 litre model had a steering ratio of 13.8:1 while the later ratio was relaxed slightly to 14.9:1. You’d be hard pressed to tell the difference. Eager gearheads will probably notice it. Both steering racks work well with the cars finely balanced chassis. The car exhibits an almost perfect 50/50% weight distribution split and is very controllable at the limit. I’m not a fan of the digital sweeping tack, it seems gimmicky in what is a no nonsense driving machine.

The CR comes with the 2.2 liter F22 C1 engine. Having driven both an S2000 equipped with an F20C and an F22 C1, a CR edition and the roll out Ultimate edition, I think my favored configuration would be the earlier high revving motor, perhaps with the Japanese higher compression ratio 11.7:1 Compression ratio (if only octane ratings allowed) mounted into the Club racer stripped out shell with the earlier closer ratio gear set using the earlier 13.8:1 steering ratio.

In summary this car has all the hallmarks of becoming a 5 star classic. It’s the last of its kind, certainly has a cult following and the engineering is first class, bespoke and unique.

Posted in Automotive | Tagged 4 cylinder, 9000 rpm, High performance, Honda, rear wheel drive, S2000, sports car | Leave a comment

2 valve and 4 valve gasoline engines

Posted on October 14, 2010 by Tiger Core

I often get asked about the merits of a two valve cylinder heads relative to a four valve. A two valve configuration cylinder head in gasoline engines doesn’t necessarily represent a viable alternative to a 4 valve cylinder head design but before coming out with all the clichés it really does depend on the operation of the unit and the market it is aimed at. Like any engineering solution there are pros and cons. It’s worth understanding the compromises. For the purposes of this discussion we will focus on naturally aspirated engines ( non turbo or supercharged configurations)
The next thing will be to seperate home modifed cars from production cars by the manufacturers, the manufacturers are far more constrained (with emissions and durability and noise levels etc etc to name but a few), and there’s alot of unscrupilous “pub talk”- with people claiming to get 100/Bhp / litre from naturally aspirated 2 valvers all the time!
This article will focus on the most difficult of all: Production naturally aspirated cars design to be sporty road units- NOT race engines.

To Start with lets set some boundaries and look at some of the best of both breeds and what they achieve:

The most difficult task is to obtain high BHP/litre from a Naturally aspirated engine (like BMW and Honda and more latterly, Porsche) and THEN achieve good BMEP (or specific torque at low speeds). The best example of this is in the BMW E36 Euro M3 3.2 litre S50 engine. Infact I would rate the E36 M3 3.2 litre way above in terms of achievement over the Honda S2000, no other car can achieve close to 14 bar BMEP at 3250 rpm and over 100 Bhp/litre at 7400 rpm-such incredible range. Also put into perspective that this was achieved in 1995. The newer CSL is even more impressive as it achieves 14.3 bar BMEP (113.8 Nm/litre or 83.9 lb ft/litre) and 360 Bhp from a 3.2 litre (110.9 Bhp/litre- but not the torque band or range) . The Porsche 911 (997) GT3 is a more recent example and it achieves: 415 Bhp@7600 rpm (113 Bhp/litre) and 299 lb ft at 5500 rpm from 3.6 litres or 14.15 bar BMEP (112.6 Nm/litre or 83 lb-ft/litre).

From a production and design for manufacture perspective it is extremely difficult to get 100 Bhp per litre from a 4 Valve . I would set down the yardstick at anything above 105 Nm/litre (77lb ft/litre) out of a 4 valve unit and quite hard to achieve in practice.
The very best two valve I’ve seen approach perhaps 80/Bhp/litre from the 911/993 Porsche RS. It makes 300 Bhp from a 3.8 and produces 262 lb ft. That is 11.8 bar BMEP or 69lb ft / litre 93.5 Nm/litre. It has very good flowing ports for a 2 valver engine (especially for the bore size) and consequently it’s very oversquare with the resulting poor surface to volume ratio. The ports are heavily biased towards flow rather than motion. The poor surface to volume ratio makes poor use of the engines breathing while the low in cylinder motion leads to a burn that isn’t as fast as it could be. To address the second issue it has a twin plug configuration which shortens flame paths (needs about 6 degrees less ignition advance across the board), allows a higher compression ratio (which in itself adds to specific torque number) by making the engine less knock limited. It should also be borne in mind that the 993 RS is a relatively light car and viewing its cam profiles and timings it becomes obvious that the engine design has been biased to get good top end performance. More achievable figures for less specialist production 2 valvers are like those achieved by the Chevrolet Corvette C6 ( 500 Bhp, 6.998litres, 71.4 Bhp/litre, 475 ft-lbs/644.1 Nm-67.9 ft-lbs/litre or 92 Nm/Litre- 11.56 bar BMEP) engine and the old E30 BMW M20 325i E30 unit an early example of an efficient 2 valver (68-Bhp/litre ,11.4-11.5bar BMEP (67-68 ft-lbs/litre). A more modern 2 valve BMW that achieves outstanding figures is the 5.6 litre V12 as used in the 850 CSi and massaged by BMWs M division. It makes 380 Bhp and 406 ft-lbs-which translates to almost 73 ft-lbs per litre (98.3 Nm/litre) or 12.35 bar BMEP. The BMEP figure is an outstanding figure for a production 2 valve while the engine makes 68 Bhp/litre. Like the earlier M20 this engine has very good combustion chamber surface to volume ratio, good ports that both flow well and provide the incoming charge with good charge motion (for a fast burn). The final honourable mention should go to the latest Dodge Hemi 5.7 engine fitted to the 2009 Dodge Ram. 390 Bhp from a 5.7 and 407 ft-lbs translates to 68.8 Bhp/litre, 71.8 ft-lbs per litre/ 97.4 Nm/litre or 12.2 bar BMEP. This engine has a inherently good flowing Hemi cross flow layout (an advantage over the Chevy LSX wedge chambered engines), twin plugs for a faster burn and uses a speed density MAP based engine management system to lower intake losses (this engine will be covered in some detail in a future article). It is all the more remarkable because it is churned out in the 1000s out of Chryslers Saltillo plant, is cheaper to build than either the Chrsyler 4.7 V8 or the venerable outgoing 5.9 “LA” engine. From an engineering point of view this is quite an achievement. So overall for the 2 valvers let’s set the yardstick at anything above 67-68 Bhp litre as being great and 11.4 bar BMEP quite an achievement, while above 70 Bhp litre is good going along with 11.8 bar BMEP (69ft-lbs per litre or 93.5 Nm/litre) while a 2 valver achieving 80 Bhp/litre is exceptional and is most likely to have a peaky torque curve optimized towards good top end performance while any BMEP above 12 bar is exceptional.
Next I’d like to go into some depth of some of the science involved. It’s a common myth that a 2 valver inherently produces more low speed torque than a 4 valver. If everything else was equal, the 4 valver can be designed to produce the same, and usually a little bit more low speed torque than the equivalent 2 valver. We’ve already seen this by viewing the highest achievable BMEP/specific torque values the very best 4 valvers make compared to the very best 2 valvers.
The truth is that because a 4 valver breathes better, most manufacturers take advantage of this to tune these engines (via cam profiles and intake/exhaust tuned lengths) to give good top end performance.

Torque Beast: Dual Vanos E39 M5 BMW

The V8 M5 engine as fitted to the E39 BMW was an engine that was tuned mainly for torque and a wide powerband. Even at 1700 rpm this engine is making more BMEP than more of the best two valvers at peak. You could argue that it has variable valve phasing (vanos), but variable cam phasing itself won’t increase the peak BMEP number but increase the torque spread.

On the other hand if you try to force a 2 valver to approach the same levels of Bhp/litre as a 4 valver (using tuned lengths and cam profiles etc etc), you’ll find that it is INFACT the 2 valver that becomes very peaky indeed with peak torque occuring very close to peak power- and therefore a narrow powerband.

The Volkswagen Golf GTi 1588 cc mk 1 is a good example of what happens when you tune a 2 valver
101 lb ft at 5000 rpm (10.8 bar BMEP), 110 bhp at 6100 rpm (69 Bhp/litre).
Other good examples of peaky 2 valve engines tuned for high rpm are the early air cooled mechnically injected early 1970s Porsche 911 engines 2.2 and 2.7 RS

An RS 2.7 produced 210 bhp / 157 KW @ 6300 rpm and Torque of 254.89 Nm / 188 ft lbs @ 5100 rpm BHP/Liter which is a whopping 78 bhp / liter and 11.92 bar BMEP

The central spark plug of the 4 valver does help with faster burn rates (due to shorter flame paths), this is good for catalyst light off- for emissions, and EGR tolerance at part load (for modest fuel economy gains), however, this must be traded off as 4 valvers usually have less in cylinder charge motion (a collective term that encapsulates both the commonly used tumble and swirl terms) than 2 valvers (in cylinder motion good for fast burn) and 4 valvers all too often have to rely on in cylinder tumble motion rather than swirl. In terms of turbulence length scales- the tumble motion breaks down to small eddies when the piston reaches TDC, where as swirl motion doesnt decay as much, so swirl motion of a 2 valver will typically benefit burn rates later in the cycle.

A 4 valve engines will usually have more friction- at lower engine speeds-especially- not good for fuel economy. This is because Valvetrain friction predominates at lower engines speeds as a proportion of the total engine friction and this apportionment comes down with increasing engine speed

The 4 valver allows good valve area for a small combustion chamber, where as to get that kind of valve area on a two valver you end up with a very oversquare chamber- like a air cooled Porsche 911 or a Dodge Hemi which is far from ideal.

Posted in Automotive | Tagged BMW, BMW S54 M3, BMW S62 M5 engine, BMW V12, Chevrolet LSx, Dodge Gen 3 Hemi, Honda S2000, M20, Porsche, RS | Leave a comment

Chrysler Big Blocks

Posted on October 12, 2010 by Tiger Core

In the middle of a major refurbishment of the Chsyler Big Block in my 1970 E body Dodge (That’s a Dodge Challenger to the uninitiated) I thought I would share the fruits of my resserch on the subject here in this blog. The base project engine in question is a 1970 440 cubic inch (7.2 litre) “RB” motor using cast iron “915″ cylinder heads, a single plain Mopar M1 intake manifold and a camshaft of about 290-300 deg advertised duration with about .550 in valve lift (using Harland sharpe 1.6 rocker arms)

Valve cover removed showing Harland Sharpe 1.6 ratio (1.5 is stock) Rocker arms

Much like BMW in Germany today or Honda amongst the Japanese, the centerpiece of performance Mopars has always been their powerplants. The Chrysler/Dodge RB or ‘raised block’ engine was an evolution that arrived 1 year later after the Big Block ‘B’ engine that arrived in 1958. The RB started life in the late 50s as a 413 cu in capacity.

The B series engine came about as Chryslers need for rationalisation of an overly complicated V8 engine range in the same segment. It had quite humble beginnings, with the requirement to push the fairly heavy cars of its line. In line with competitors of the time a wedge combustion chamber design was favoured over the heavier and more complicated polyspherical design (despite the flow advanatage). It took a while for this new Big block to gain a good reputation, partially because it replaced the lamented early hemi design. (It seems ironic today that the small block Chrysler engine kept the small polyspherical combustion chamber layout until Chrysler finally decided to evolve this into a wedge design also in the late sixties- only 35 years later this small block provided the basis for the new twin plug Hemi of today-an article for another time!) .The capacities started out with were 350 cu in, a 361 and a year later the raised block 413 cu in. This 361 was available as an option on many vehicles of the time and soldiered on in truck applications and even Winnebago and heavy duty trucks until as late as 1978 (the final car application was 1966). The 350 cu in motor is related to the omni present 383 cu in big block beloved of Mopar fans of the 1960s and 70s and infact all parts are compatible with the exception of the pistons and waterpump . Although related to the B and RB big block these early derrivatives weren’t considered high performance motors as evidenced by the commonly fitted 2 barrel Stromberg carburetion.

The event of most note to Mopar performance enthusiasts was the introduction of the B engine coded as the ‘D500’ in 1962. This was both a factory and dealer option and consisted of a cross ram induction manifold with 30 inch intake runners fed by two carter 4 barrel carburettors into the now 383 cu in engine. The induction system certainly looks interesting with the dual carters overhanging the valve covers making about 343 Bhp (bear in mind that this is not directly comparable to the quoted figures we’re used to today- as it is rated as SAE of the day and a laboratory gross power curve was taken and quoted rather than net . Look out for a forth coming article that covers BHP ratings and how they stand relative to one another.

The Max Wedge was perhaps the ultimate evolution of the Mopar Big block concept and came about in 1963 and 1964.

The 1960s was an era of new ideas and more innovative powertrain ideas came out of Chrysler than any other Detroit manufacturer. Out of the big three Chrysler was considered the advanced engineering division. Even though the groundwork was set in the 1950s but the Max Wedge Motors of the early 60s is what sparked and kept Mopar racers at the forefront. This remained true until the demise of the Muscle car in the early to mid 70s.

During the 1950s some young engineers, most notably Dick Maxwell, Jim Thornton and Tom Hoover, formed the RamChargers racing team. With only limited resources they nevertheless left an impressive mark on drag racing during this era, and laid the groundwork for what was to come. This group of racers who lamented the passing of the old polyspherical Hemi engine of the fifties would almost exclusively races these motors.

1962 also saw the introduction of the 413 cu in Max Wedge (as fitted to the Dodge “Ramcharger”) with ram induction tuned intake lengths (now reduced to 15 inches) not dissimilar to the tuned length cross intake used on D500 of 1962. This was very unusual for the time and quite a feat considering that this engine was carburetteured hence the intake manifold must serve dual purposes of both good fuel delivery distribution as well as airflow distribution and in this case- tuning. Although it produced great power (400 Bhp gross) for the day, the elaborate intake setup proved to be less than perfect at the track, where the tradeoff of power against a narrower power band was not deemed worthwhile, and in 1963 the 413 Max Wedge intake was reformed. The 426 cu in capacity (the same as the famous 1960s dodge Hemi engine) Max Wedge engine was known as the stage II Max wedge and debuted in July 1^st 1963. It was only intended for racing use and this capacity was used to take full advantage of the 7 litre cap imposed by NASCAR.

These are some of the modifications to enhance performance and reliability that Dodge implemented over the stock big block RB engines

New short-ram intake manifold to increase power output over at speeds over 4,000 rpm; tappets could be adjusted with the manifold in place
Port areas of each cylinder head around 25% larger than with the standard 413 engines, with stainless steel head gaskets and a special deck structure for better sealing
larger valves (2.08 inches intake (the same size as the later 915 and 906 cylinder heads used in the later 440s)
Oversized long-branch exhaust with three inch outlets and cutouts; two-inch diameter twin tailpipes
Three-valve fuel pump with high spring load; electric fuel pumps available as an option
Larger oil galleries, a larger oil intake tube, larger main and rod bearing oil grooves, and a fore-aft swinging oil intake in the sump to assure circulation when the oil moves to the rear of the pan (on hard acceleration).
Forged aluminum pistons with a chrome-plated iron top compression ring; connecting rods were individually magnaflux-inspected.
Mechanical lifters for high engine speeds with high strength valvespring retainers and springs. Rocker arms included lock nuts on the lash adjusting screw.
Hardened journals and alloy bearings for extra crankshaft capacity; specially balanced drive shaft
Distributor and dual breaker points
Heavy duty manual gearbox or optional automatic, set to upshift at 5,600 rpm, with highest maximum overall breakaway ratio (5.39:1) and overall efficiency of any stock automatic.
Sure-Grip rear axle (limited slip differential) and heavy duty rear leaf springs standard with the Ramcharger engine.
11 and 13.5:1 compression ratios

The stage III Max Wedge was the final of this racing series of engines to be released .It came out in 1964 and featured a revised cylinder head with a new camshaft design.1964 was also the year when introduced the famous Hemi (or elephant as it became nick named) into racing. The original Hemi is a whole story into itself and will be covered in a future issue.

Back to production, the 440 RB engine capacity was introduced on sale to the public in 1966 along side the 426 Hemi.

440 introduced 1966, along with legendary 426 hemi “elephant”. Thanks to development of precision thin wall casting techniques used to make the 1964 small block 273 ci V-8, this same RB could be pushed out to 4.32 inches bore which gave the 440. To achieve the 440 cu in capacity (7.2 litres) the engine shared the stroke of 3.75 inches with the 426 Hemi as did all the ‘RBs’ .It was first introduced in the 1967 GTX. The bore centres of the Big block mopar are 4.84 inches which leaves 0.52″ (13.32mm) of bridge distance between cylinders.

1969 is what is earmarked as landmark year amongst Mopar fans, as the introduction of the 6 pack intake set up on the 440s. The 6 pack set up refers to the carburetion. It used an ‘High rise’Edelbrock intake manifold set up to utilise a trio of Holley 2300 series twin chokes. Collectively rated at 1200 CFM (cubic feet per minute). Usually with high flow rated carburetion you can compromise the precision of fuel delivery at low engine speeds and loads due to slow gas velocities through the venturi. The 6 pack opened progressively with the engine running on centre venturis only at low loads, for better low flow rate fuel delivery-hence better gas mileage (in theory!). The Edelbrock intake manifold design is good in the way it ensures the carbs are as equidistant as possible from the cylinders they feed, thus ensuring good fuel distribution- of significant importance on a carburetteured car. Good fuel distribution is also significant for fuel economy as when you map the mixture globally (‘mapping’ is a relative term when it comes to carburetion) you are not limited as much by your leanest cylinder and misfire. Internally the engine got stiffer Hemi valve springs with chrome flashed valve stems and molybdenum rings and a distributor with dual breaker points all to ensure better running at higher rpm.

A low-taper cam and tappet setup was designed to keep the Tappet spinning and minimizing wear. You will not find this on similar era GM engines.

Performance of gasoline engines is primarily about airflow. So the next part of the article will focus on the cylinder head where the power and torque is made. I’ll cover cylinder heads from 1967 onwards as these are what are most readily available and hence were easier to come by for our testing.

The heads are identified here by the last three digits of their casting codes.

Pre 1967 cars including a lot of the Max Wedges used ‘516’heads

In 1967 915 cylinder heads were introduced and fitted to only the 440 cu in engines initially while the 383s kept using the 516 heads. It featured a revised port design mated to the closed chamber (read high squish) of the earlier 1964-1966 cylinder heads. The Chamber volume was typically 78.5 ccs. The closed chamber and high squish makes for better in cylinder charge motion –which contributes towards a faster burn (the benefits of a faster burn will be covered in some depth in forth coming article(s)). This is probably the reason why racers favour these factory cylinder heads so much, learning through trial and error over time what we know analytically. The 915 castings typically came with 2.08 inch diameter intake valves and 1.6 inch exhaust valves (small) as found on the previous 516 cylinder heads. The Magnum version of the 915 cylinder heads used 1.74 in diameter exhaust valves (as was often successfully used in certain high performance applications in the years gone by). For 1968 the cylinder head casting was modified again. In this case the intake and exhaust ports were kept the same by the chamber was now a bigger volume (88 ccs) ‘open chamber’ with a lot less squish and consequently slower burn. This slower burn impacts thermodynamic efficiency adversely but helped Chrysler to reduce Nox emissions to meet SMOG requirements. Although the ports were the same there was a slight benefit in flow figures due to the de-shrouding effect of the open chamber to the valves. This 906 cylinder head was fitted to all Mopar Big blocks from 383 to 440 and the 2.08 in intake/1.74 in exhaust valve sizes were now standard across the board. This cylinder head stayed until 1971. Despite the slight flow advantage the 915 cylinder head offers the best performance.

In 1971 along came the 346 cylinder head. This variant had the same open chamber as the 906 and very similar exhaust port geometry as both the 906 and 915 but the intake port was a radical departure. Just viewing and feeling the cylinder heads one can tell the priority was for emissions reduction. The roof of the port is much lower (the height of the roof of the port relative to the valve seat and the port angle of attack represent some of the biggest hitters when it comes to port flow outside the valve seat itself) with a much tighter short side radius with an obvious hump introduced there. From an OEM development engineer perspective it looks to me like that were really trying to induce a tumble biased in cylinder charge motion. No doubt this was for emissions, perhaps to aid homogeneity of the incoming fuel air mixture. None of this is good for the performance orientated enthusiast. The 346 casting featured from 1971-1973, which was followed by the 902 casting (1974), the 975 casting (1975 ) and the final casting before the death knoll of the Big Block Chryslers , the 452 (1976-1978). All of the castings mentioned have the same exhaust port design, while the later ‘smog’ type castings (346 and onwards) all share the same flatter intake port design and differ only in durability details such as hardened valve seats, reinforcement for better crack resistance and an enlargened valve guide boss in the valve seal area.

We will leave our flow results to the next section where we assess this Mopar big block, superficially at least against its big three opposition…more to follow…

Posted in Automotive | Tagged Challenger, Chrsyler Big Block, Dodge, Harland Sharpe, Max Wedge, Mopar, Muscle Car | Leave a comment

Auto-Scape

Chrysler 426 Hemi in depth dyno test and analysis using modern empirical and simulation techniques

Our new arrival

Car Styling, DNA and “Design Language”

Test Drive 2011 Dodge Charger with 3.6 litre pentastar V6

1998-2003 Jaguar X308 XJ8(R)- An under rated scorching luxury Saloon

So Long S2000 (Gone but Never Forgotten)

Technical Focus

2 valve and 4 valve gasoline engines

Chrysler Big Blocks

Archives

Meta