Top Ten Tuning Tips

In response to Mr Jon, when I had my first atmo, it hadnt been run for two years, and when I bought it I had it dynod and it make believe it or not exactly 160bhp, factory power. All I did to it was advance the timing and fit an adjustable fuel regulator and it made 170bhp...about £120 pounds worth of mods including the rolling road session. It did make a real difference in the midrange pull.

Ok, so here's a question that will show my ignorance, but is a 'real world' scenerio.

You have an atmo and you want to improve the low end acceleration. Say the 0-60 time by a second. What options have you got, pros and cons, how much would it cost and is it worth the bother?

[Alpineandy]

I did find a noticeable increase in power the other day when I filled the car up with leaded fuel! A friend told me about a place in Kensington that still sells the stuff - pricey but good to know it's harming the environment.

Bad news for you, Leaded isn't harming the enviroment any more than un-leaded. The lead is replaced by other carcenogenic chemicals!!!

I'd be suprised if your leaded tankful made any difference over a tank of super-plus / optimax.

I reckon an extra 30 bhp should be plenty to lower the 0-60 by about a second. I have a pc program called Desk Top Drag Strip which apparently is accurate to a very high degree provided you have all the information ( I would need full rolling road dyno plot) I have info for the turbo from my own experience but not for a n/a car. If any one has a power graph I'll run it through the program and see what the results are.
But 30bhp should give a 0-60 close to that of a turbo car. A custom induction kit, Devil headers and a good exhaust system along with rejetting of the carb and a play with the ignition timing on a rolling road should get you close to that figure with no loss of bottom end power. Remember N/A cars are lighter and the throttle response better than on a turbo - turbo much torquier once on boost though. A lightened flywheel can improve your 0-60 too just through improve throttle response.

Ok, so here's a question that will show my ignorance, but is a 'real world' scenerio.

You have an atmo and you want to improve the low end acceleration. Say the 0-60 time by a second. What options have you got, pros and cons, how much would it cost and is it worth the bother?

I think Ive said this before, If I had an atmo, id fit a blow through solex carb instead of the standard carb, and fit a set of V6 turbo manifolds, turbo and pipework, sourceable off an old 25 turbo for instance. Run it at very low boost say 3-4 psi and your going to increase bottom end torque and top end power, with out sacrificing any of the cars original charactieristics. Im stripping out my turbo engine and fitting a Safrane high compression engine and doing the same thing, max 5 psi.

Do the inlet manifolds for aspirated and turbo cars have the ports in the same place? The inlet manifold off a GTA Turbo or 25 Turbo engine will not fit the 3.0 litre heads, the inlet ports are in a different position on the heads relative to the manifold. I assume this will be the case with your engine - I could be wrong but you best check. I looked into having spacer plates made up but it was complicated and quite expensive so had to buy an A610 inlet manifold. You could consider keeping the injection and just making up some plumbing to force air into the standard plenum but this may make it difficult to mount the turbo. Something I looked at was reversing the side the exhaust manifolds are fitted, cutting them down and putting a flange on them to run T2's each side.

Im going to fit the 610 inlet manifold, and use the V6 turbo manifolds. Ive got a spare old V6 turbo engine so I wont have to mutilate my current one. Just have to sort out the bottom engine casing and sump, oil feed, dizzy etc. Im only doing this because Ive lost faith in my current engine. When I bought the car many years ago, in its history it had had the headgaskets done twice, and heads skimmed twice, and I think the timing is slightly out on both the banks. Unless I do a complete rebuild I wont be happy. I always loved my old atmo, so I want to get the best of both worlds. Think I need a box rebuild/ driveshaft replacement. Under load in 3,4,5 there a high speed drumming, same as the wheel speed. Ive never had this before on a GTA. Has anyone had this problem before and diagnosed whether it was shaft or diff? Would like to know before I unnessecarly rebuild my box!

Is the noise worse with revs or louder with road speed? Take it out of gear at high speed, if it still makes the noise its more likely to be a wheel bearing or drive shaft than the gearbox. If you need the box rebuilt theres a guy in the 21 Turbo club who is good and cheap (hes a Renault technical expert), or try Moggy, see what he can get you an exchange one for.

It only does it under load, it stops on deaccelleration or coasting even at the same speed, though it can still be a shaft resonating under load. Whats strange is in 2nd at 40 at full load it doesnt do it, but in 3rd at the same speed under load it does. Ive got a feeling it may be final drive, previous owner had it rebuilt by Renault to the sum of £2100, but I think he seriously abused the car. Ive got a spare box, but again I think its better to rebuild than replace, just to be sure!

Ill just add too, I used to put the GTA on the rollers all the time and the last four runs the transmission losses kept going up. I was measuring 64bhp loss on the last run, they normally sit around the 40bhp mark!

I had a rather scary drumming noise, only on load, at speeds above 40ish and changing in pitch with road speed. It turned out to be loose wheel nuts that some idiot (i.e. me!) had not tightened up properly.

I did stop after a few miles and kick the wheels to check that they were Ok and they felt solid so I carried on. It was only when I got to my destination and got hold of a wheel brace that I discovered that they were not perhaps as well torqued as I'd have liked them to be.

Its a long shot but worth eliminating before splashing out on a diff/box rebuild.

Tony, this desk top drag strip program you have. Can you sort me and anyone else a copy out please ???
Or maybe even post a download link on this or another website ??

Thanks

I have the old one which is on a 3 1/2" disc. I'll make a few copies , if any one wants one let me know on a PM. They have a much better version out now, still with the same name - and also Desk Top Dyno which will tell you how much power you have from inputting different engine parameters. http://store.wpsracing.com/mrgasdesdrag.html