CRS Cobra engine upgrades

[Alan Faulkner-Stevens]

This note is about the feasability of engine upgrade work on the first 25 odd CRS cars produced plus the implications of any modifications. These are cars fitted with the American specification 302ci engine. The later produced cars had an Australian specification engine fitted. From checks on numerous CRS cars, ones built around 1999/2000 period it appears they were fitted with engines produced in 1994 and most appear to be originally intended for the Mustang model. This may also be the case in some Superblower vehicles. These engines have a very different ECU than vehicles with computer engine management systems built up to 1993. A check on the printed label on the ECU and subsequent decifering can verify the actual application. But 1994 and 1995 produced ECUs have been programmed in such a way as to make any mechanical upgrade undertaken on the engine impossible to recalibrate via reprogramming of the ECU. This is not the case on earlier units.
   When Ford engineers were calibrating the 1994/95 units new very strict emission standards had been introduced into the States and they knew any engine upgrade work could throw off the emission calibration thus rendering the car illegal. Therefore the ECU has been produced in such a way as to not allow any modifications.
   There is only one way to upgrade and engine and ensure it both runs correctly and is fully legal and that is to replace the original ECU with a fully programmable unit with can be calibrated via a lap-top computer whilst the car is on a rolling road.
   I shall now raise a slightly contentious issue now which is the replacement of engines which are fitted with catalitic convertors and are computer controlled with an engine which has a carburettor induction system.
   If you have a vehicle say produced in the year 2000,when that car was registered it had to meet all current constuction/certification and emission rules applicable for that year. Each CRS was individually certified by gaining a S.V.A. [Single Vehilce Approval] thus vefiying the car was legal according the rules set down for a year 2000 motor car.
   AC Cars did this for each CRS manufactured. Once your computer system has gone and a carburettor fitted in its place there is very little chance of that engine ever meeting the tight emission laws applicable to that year and thus passing an MOT Test.
   Unless you can convince the D.V.L.A. otherwise when you take the modified car for an MOT things can get difficult. The tester logs on and the details of your car, chassis and registration number, are fed into the computer. Up comes details of your car saying manufactured in 2000 and therfore the tester knows how far he or she has to check.
   Remember after the emission test the recorded details are sent directly back to the DVLA who then know whether your car passed or failed.
      Tuning a CRS engine is not an impossible task it just requires a little more dedication and determination and worst of all slightly more money than first anticipated. But hey, AC members are made of sterner stuff, aren't they?
   Alan Faulkner-Stevens

[keithjecks]

I have often wondered what could be done to tune a 302cu Ford engine. I have extensive experience of tuning Caterhams, and conceptually cannot believe it would be hard to apply the same knowledge to a Cobra. There are numerous makers of throttle bodies (e.g. Weber Alpha) that are designed to fit a manifold that Weber carbs fit. If the SVO stage III heads and cam were fitted (as per the Lightweight MkIV's) with the modern electronic throttle bodies and the right mappable ECU (such as Weber Alpha or mems), then I don't see why a genuine 350 bhp or so with great driveability and emissions compliance shouldn't be possible. Steve Greenauld near Dartford has the rolling road and software and mapped a Caterham road/race car for me for about £400, which goes like stink, but passes the relevant MOT tests - I am sure he would relish a Cobra.
   
   If I still had a cobra, I would love to try that!

[Mark-Anthony]

Hey Guys,
   
   Have a look at my reply on under the heading "CRS owners unite".
   
   You can get another 50% out of your CRS without upsetting the DVLA and I suspect that you can actually get an "at the back wheels" figure of about 350bhp/350lbs ft with a little application and a lot of cash.  You may need to remove your brains to drive it though!
   
   I'll be producing an article in full for ACtion and for the forum before the end of July (including costs and sources and telephone numbers).
   
   The car will be with me at the first CRS Owners club meet!
   
   Regards
   
   Mark-Anthony (Chassis 22)

[Max Allan]

quote:Originally posted by Alan Faulkner-Stevens
   
This note is about the feasability of engine upgrade work on the first 25 odd CRS cars produced plus the implications of any modifications. These are cars fitted with the American specification 302ci engine. The later produced cars had an Australian specification engine fitted. From checks on numerous CRS cars, ones built around 1999/2000 period it appears they were fitted with engines produced in 1994 and most appear to be originally intended for the Mustang model. This may also be the case in some Superblower vehicles. These engines have a very different ECU than vehicles with computer engine management systems built up to 1993. A check on the printed label on the ECU and subsequent decifering can verify the actual application. But 1994 and 1995 produced ECUs have been programmed in such a way as to make any mechanical upgrade undertaken on the engine impossible to recalibrate via reprogramming of the ECU. This is not the case on earlier units.
   When Ford engineers were calibrating the 1994/95 units new very strict emission standards had been introduced into the States and they knew any engine upgrade work could throw off the emission calibration thus rendering the car illegal. Therefore the ECU has been produced in such a way as to not allow any modifications.
   There is only one way to upgrade and engine and ensure it both runs correctly and is fully legal and that is to replace the original ECU with a fully programmable unit with can be calibrated via a lap-top computer whilst the car is on a rolling road.
   I shall now raise a slightly contentious issue now which is the replacement of engines which are fitted with catalitic convertors and are computer controlled with an engine which has a carburettor induction system.
   If you have a vehicle say produced in the year 2000,when that car was registered it had to meet all current constuction/certification and emission rules applicable for that year. Each CRS was individually certified by gaining a S.V.A. [Single Vehilce Approval] thus vefiying the car was legal according the rules set down for a year 2000 motor car.
   AC Cars did this for each CRS manufactured. Once your computer system has gone and a carburettor fitted in its place there is very little chance of that engine ever meeting the tight emission laws applicable to that year and thus passing an MOT Test.
   Unless you can convince the D.V.L.A. otherwise when you take the modified car for an MOT things can get difficult. The tester logs on and the details of your car, chassis and registration number, are fed into the computer. Up comes details of your car saying manufactured in 2000 and therfore the tester knows how far he or she has to check.
   Remember after the emission test the recorded details are sent directly back to the DVLA who then know whether your car passed or failed.
      Tuning a CRS engine is not an impossible task it just requires a little more dedication and determination and worst of all slightly more money than first anticipated. But hey, AC members are made of sterner stuff, aren't they?
   Alan Faulkner-Stevens
   

[Max Allan]

Sorry messed up previous post.
   
   Below is article regarding changes made to the EEC used on 94-95 Mustang engines members might find interesting. As far as I'm aware it is possible to reprogram the EEC to accomodate engine mods using a "tweecer" hooked up to a laptop. I sure hope so, because my Brookland Ace has developed a tendancy to stall since doing the usual heads/intake mods - a bit uncool when the masses are awaiting an impressive launch away from the lights - and no amount of fiddling with the TB has solved the problem. Even tried cleaning the O2 sensors to no avail, so reckon a tweecer is the only solution - if I can make it work!!
   
   
   EEK vs. EEK:
   THE SHOWDOWN
   By: Mike Wesley
   --------------------------------------------------------------------------------
   
   Some of you may be asking why the 94-95 Mustangs seem like they are so much slower than the older cars. We've all seen them at the strip running quite a bit slower. They are heavier, but the difference in times doesn't add up to the difference in weight. What gives? Well, a lot of it has to do with the differences between the '94 - '95 Mustang EEC and the '93 or older EECs. In 1994 Ford did a major redesign of both the EEC hardware and EEC software. The end result was a much 'cleaner', 'smoother' running car. If you own one of these Mustangs or know someone who has one, you've probably heard of problems getting them to start, idle, and run like a stock 1987 to 1993 5.0 after doing some modifications. Well, you can thank the Feds and Ford for that. Ever increasing emission requirements led to major changes inside the EEC to produce better control of the powertrain. Of course this hurt the overall ability to modify the car. It became much more sensitive to minor changes. With tighter requirements for warranty, the '94 - '95 Mustang owner ended up with an engine that made the same power numbers on the dyno, but not the same numbers at the track. Let's go through some of the major differences and see if we can find the trouble spots. This will be broken down over a series of articles, because it is very complex.
   
   
   
   
   PART 1 - EEC SPARK:
   In the '93 and older EECs, spark advance at WOT (Wide Open Throttle) was based purely on RPM. When you went into WOT, the EEC jumped to a separate spark function to give whatever Ford thought was the best spark curve. Of course we all know they didn't really make it, because you can pick up some power by advancing the distributor. This wasn't their fault since the calibration was designed to run everywhere with different types of fuels. Everytime you went to WOT in a 93 or older car, you ran basically the same spark curve run after run. If you look at figure 1, you can see a stock WOT spark curve taken from a 93 5.0 GT 5spd.
   
   In the '94 - '95 cars, Ford made a major change to the spark calculations. The WOT spark function was deleted and now the car uses the same spark tables for both part throttle and WOT spark calculations. The problem with this is the spark table is based on RPM and Load. The formula for Load is basically the amount of incoming air, ratioed against how much 1 cylinder can hold at standard pressure/density. You can sort of think of Load as volumetric efficiency. The EEC uses the MAF to determine Load. It is a direct measurement of how much air is entering the engine. You might be wondering what the big deal about Load is. Well, since Load is used in the spark calculations, any change in Load will affect how much advance you get. Since the EEC uses the MAF to determine Load, any change in the MAF will change the Load calculation. Changes in the cam and anything that puts more air into the cylinders will also affect Load. Change the flow characteristics and you change Load. Let's see how this works.
   
   To simplify the whole spark calculation, we are going to combine all the spark calculations into one table and use actual Load values seen during testing. In reality there are quite a few of them for different things. If you look at Figure 2, you'll see a spark table from a 1994 5.0 GT 5spd. When you go into WOT, the EEC will pull spark values from the top two rows of the table. Figure 3 traces a test run done with a bone stock 94 GT. Notice how as RPM increases, Load decreases and spark advances a bit. The decrease in Load is due to volumetric efficiency of the engine dropping off. A typical 5.0 is not the most efficient engine around. If you compare the spark values calculated by the 94 EEC to the 93 values, you'll see they are not too much different. Change something on the engine and it's a whole new ballgame. Let's take a MAF change as an example. Figure 4 shows a MAF transfer function for an aftermarket MAF that we tested along with the stock curve. Notice how the aftermarket MAF's curve doesn't always follow the stock curve? When the EEC looks at the aftermarket MAF and converts the voltage into airflow using a built-in lookup function, it will calculate differing amounts of Load as RPM increases. In our example, we'll use 5500 RPM and 4.6 volts out of the MAF. In our baseline car at 5500 RPM, the EEC calculated a Load of .78. Input that into the spark table and we get an advance a bit over 26 degrees. Going back to figure 4, at 4.6 volts the aftermarket MAF 'fools' the EEC into thinking MORE air is entering the engine than what really is so it calculates a higher Load. With this particular MAF on our baseline car, we saw a Load value of .91 and the resultant spark advance was 25 degrees. Wow! By changing the MAF, we lost about 1.4 degrees of spark advance! On the dyno, this particular car lost about 14HP when the aftermarket MAF was installed. Some of this was due to the loss in spark and fuel which we will get to in a later article. It looks like there is a simple fix to this by bumping the distributor up. Sounds good, and it will help get back the loss in top end spark. However, there could be a catch if we now look what happened to this car at 2500 RPM. The baseline car had a Load value of .75 @ 2500 RPM and spark was 24 degrees. After putting on the MAF @ 2500 RPM, the Load was .65, and spark was roughly 26 degrees. Hmm. We got more bottom end spark with the MAF since it 'fooled' the EEC into thinking LESS air was entering the engine. Looks good so far and the car did make more power at 2500 RPM than it did stock. Now to fix the top end spark loss, we bumped the distributor up 5.5 degrees. This included the 'normal' 4 degrees everyone puts into the car plus the extra spark to compensate for what we lost with the MAF. Now the car made up the lost power plus some on the top end and lost 10 HP at 2500 RPM. Why?
   
   Due to what the MAF was telling the EEC, and how it changed Load and advanced the spark 2 degrees, our bump in the base advance made the total spark advance at 2500 RPM a bit over 30 degrees. Way too much advance at 2500 RPM. Figure 5 shows the relationship between torque and spark advance. The very top point in the curve is called MBT or Maximum Brake Torque spark. It's basically the amount of spark advance that produces the maximum amount of torque. If you go above or below the MBT point, you lose torque. As you continue to advance the spark, you'll reach a point in the curve called BDL spark or Borderline spark. This is the amount of spark advance where the engine just begins to knock. On a normally aspirated, low compression engine, BDL occurs at advance values higher than MBT. On high compression or supercharged engines, BDL can occur at advance values lower than MBT. Raising the octane value of the fuel moves the BDL point higher up. Going back to our low RPM example, further testing found the MBT point at 2500 RPM to be 28 degrees. Now came the question of what to do. Should we lower the base advance to get the bottom end power back and sacrifice some top end power, or leave it alone? However, should we go for the top end power, but sacrifice the bottom end? That choice is up to the owner. We opted to actually re-calibrate the EEC to run MBT spark at all RPM points by changing the spark tables. Now of course all this might go the other way depending on the MAF. It can 'fool' the EEC into lowering the Load at higher RPM which will give you more advance. It's really hard to tell what you are going to end up with.
   
   Another thing the '94 - '95 cars do with spark is retard it during a shift. The automatic cars REALLY pull out the timing, but the 5spd cars do it also. Inside the 5spd EEC calibration is a thing called Tip-in Retard. Any time the throttle is moved from a more closed position to a more open position, it can pull out some timing. When you shift a 5spd car, most people lift off the gas during the shift. The EEC senses this, and when you push on the gas again it pulls some timing out. The older EEC didn't have this 'feature'. You lose more torque during a shift on a '94 - '95 car than a '93 or older car. Why did Ford do this?? We think warranty. Ford had to replace a zillion T-5's in the older cars. Alot of them broke due to overshifting and power shifting, but alot of them broke as a result of too much transient torque. If you could reduce the torque output of the engine during a shift, the transient torque would be lower. The trans wouldn't break as easily, and thus the Tip-in Retard was born. How much timing is pulled out during a shift varies, but it can pull out as much as 15 degrees. There is not much you can do to 'fix' this except to re-calibrating the EEC.
   
   The '94 - '95 automatic cars have a torque modulation strategy installed in them to vary spark during shifts. When the EEC thinks it's time to change gears, it can pull out massive amounts of timing so the shift is nice and smooth. As far as we know there are two reasons for this. First is warranty. The AODE trans is not all that strong in stock form. By reducing the torque during shifts, you can extend it's life. Second is shift feel. For some reason Ford doesn't want you to 'feel' the car shift. Ever notice that just about all Ford vehicles with electronic transmissions shift like Town cars? Smooth and sloppy. Even performance vehicles like Mustangs and Lightnings have weak kneed shifting. What fun is that? The downside to this smooth, sloppy shifting is increased wear. Ford tends to slip the trans too much during gear changes slowly burning it up. Manually shift your car, and you'll see it shifts much better. During manual shifts you run through different sections of the trans control strategy. The older EECs with AODs (sometimes called DOA's) really had no idea a trans was attached to the engine. They did not spark retards during shifts and could actually shift quite well. They broke more often, but shifting was better. Adding a shift kit to a '94 - '95 car can help the shift feel by increasing fluid pressures inside the trans, but this does nothing to the engine torque loss during a shift.
   
   So you can probably see, tuning a '94 - '95 Mustang can be tricky. The engine remained basically the same, but the brains controlling it changed. In the next article, we'll discuss the fuel system and how minor changes to the engine can have drastic effects on how the engine runs.

[Guest]

Maybe I'm missing some thing here ..because in the states the 5.0L Ford motor ... is one of the most popular V8 engines and the parts to tune and modify these motors ... including throttle bodies ECU boxes, header heads cams are a dime a dozen... the only reason I choose not to modify my MKIV is then it becomes just another hot rod ... maybe I missed the point ... is it due to stirck emission in the UK that your trying to work around ???
   
   Ron
   NY

[Max Allan]

Hi Ron
   
   I too was/am puzzled. A flick through a Summit or Jeg's catalogue will reveal a wealth of power-adders for the 5.0L - including 94-95's. And earlier this year I imported a pair of AFR's, Trickflow upper and lower intake, Crane 1.7 rr's and Ford Racing 65mm TB plus ceramic stainless headers and have had no "issues" (apart from the occasional stall previously mentioned). It therefore came as a suprise to read that changes to the 94-95 ECU prevented modifications to 302's.
   
   I posted the Mustangworks article in response, as it explains where the later ECU differs to previous ECU's and why it is less willing to accomodate modifications to the engine. I'm no expert, but believe it is possible to reprogram it if necessary (rather than burn a new chip which is expensive over here) using a tweecer, which is able to change the ECU codes, as opposed to a PMS that only alters the info the ECU receives. Maybe others out there can shed more light on the matter?
   
   Regards emissions: unlike the USA where (according to a buddy of mine in Tennessee) most states don't even bother with emission testing, over here the powers-that-be are obsessed with car pollution. I doubt our emissions are tighter, but getting American V8's through does seem to be thwart with difficulty. I had to nigh on "cook" my own engine to get it through last time. And a mate, also with an Ace, but fitted with a brand new 4.6 DOHC and ECU, had his fail !!
   
   Cheers Max
   
   Kent

[Guest]

MAX as I think of it Allen I think mentioned converting to carberator .. hes right the more I think of it the more that is the simplest solution.  Here in the US after the ENGINE MASTERS COMPETITION the trend is windsor based block with cleveland heads.  There is a amazing amount of power to be made with the BOSS 302 style combo ... so ECU's and all that stuff with EFI is getting left behind in the V8 Ford world. I say with 2 exceptions:
   
   1. to our own MKIV's .. but never fear there are many companys that make the components like F.A.S.T and ACCEL that do make aftermarket ECU's for cars that are upgraded and yes they have to be reprogrammed.
   2. the big aftermarket trend is IR EFI independent runner electronic fuel injection.  I just ordered a custom intake to fit a 351W SVO G block and SVO C302B heads ... the hardware and electronics are available from at least half dozen vendors.
   
   SORRY to high jack the thread ... but its not impossible .. I guess I make it sound easy because its a US based motor. Its as simple as getting a programmable ECU from an aftermarket company.
   
   Ron

[keithjecks]

Max - off topic a bit. Has your freind got an Ace with a factory 4.6, or has he retro fitted it? I only ask because I thought my Ace was the only 4.6 to survive.
   
   Keith

[Mark IV]

Ace 4.6...
   There should be a couple of 4.6s out there. The light "ice blue" (LHD) car shown at the motor show in 1999, the BRG ACECA coupe and a red ACE roadster. There were a couple of Lotus powered cars, the dark grey ACE that Lubinsky drove, the black ACECA that was at the moror show as well as some others.
   Rick

[Max Allan]

Keith. I got it a bit wrong - it's an Aceca he built from scratch using a body shell obtained from the Factory at around the time the company went pear shaped, in which he fitted a quad cam 4.6. He has two Aceca's and a Brooklands Ace.
   
   I was contemplating switching mine to a 4.6 using one of the ex Jensen units recently advertised on ebay. But I'd already imported the power-adders for the 5.0L and was advised against the switch by various contacts in the States. Collectively, they reckoned with the stuff I'd got I was up to the same grunt with less weight than the 4.6. Pity, because I quite fancied a 4 cam, but in the end logic prevailed.
   
   What was the handling like on the later cars? Mine's a 94 and the ride and handling were atrocious. Fortunately, after much modification to the steering and suspension it's now a pleasure to drive.
   
   Did you see my reply to your enquiry about a car cover?
   
   Max

[Guest]

The 4.6 Cammer is a BIG engine in size and wieght ... its very costly compared to the standard V8 and doesnt make any more horsepwoer then the stadard v8 .... My Pantera Amigos also contenplate this swap very often .. but the problem is the PRO dont out wiegh the cons ... the 4.6 needs a few more years development in the aftermarket market ... and I will be eating my words.  I to fancy the Cammer ... remember the 427SOHC I found two in a garage in NY for a minimual price .. and it would be a real job putting it in a AC or Pantera.  Too much cutting.
   
   Ron

[Mark IV]

Max,
   Later cars with the 4.6 (circa 1999) handled quite well. Jan-Erik did a good job of revising the suspension. I drove both the 4.6 Aceca and the Lotus Ace and was impressed with both the handling and the ride. I also drove a late 5.0 supercharged Ace (dark blue factory demo) and it too was nice.
   Rick

[Max Allan]

The improvements must only have been to the last few cars made; Autocar in it's  February 99 road test of the Ace described the steering as the worst of any current car they'd driven!!
   
   Why it took the Ac "engineers" so long to sort out the problems baffles me. Although a repairer of Jaguars for many years, I cannot claim any particular expertise in what makes a car handle well. But applying the reverse of the adage "if it looks right, it probably is right" – one look at the steering geometry said it was all wrong!! Yet sorting the steering and ride were hadly rocket science - just time consuming. Current dilemma - do I attempt to put the icing on the cake by fitting an anti-roll bar, or is that a mod. too far?? Has anyone tried it?
   
   Max

[keithjecks]

Rather than continue to hijack this thread, I have moved the tangent over to the general forum!