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Something that is rarely akcnowledged is the fact it's torque (how much and how brutally produced) which kills the gearbox, not outright hp. A lot of folks are running insane amounts of boost (like 20-25 psi) using stock turbo's and while they might peak at no more than 220-240 hp (from which point the efficiency of the turbo compressor goes away and the amount of heat produced will negate any power gains form boosting that high, and engine backpressure gets to be at least twice the boost pressure!) they will have wheel-spinning, gut-wrenching, tranny-tearing torque lower down the rev range. Those are the people who wish Saab designed their transaxles with a quick release system... ;-) Excessive torque, in combination with FWD, will produce some unpleasant driving characteristics too, so in the real world it will be quite frustrating sometimes on a twisty back road and not all that fast, either.
On the other hand, there are people out here with c900's and power outputs in the high 200's who did not encounter any transmission problems - damien is one example - another factor is that he's into road track events rather than traffic light or strip drags, or rallying. If you don't abuse your trans with high shock loads (be it from hard 1st gear launches or yumping and hitting rocks or pot holes at speed) chances are the stock transmission will do fine for you.
Given the above, I'd recommend starting with the obvious (APC tweak with corresponding fueling upgrade, exhaust including downpipe, intercooler upgrade/fan/water injection, ignition timing tweaks) which should bring you to about 220 hp, maybe a bit more. Beyond that, I would look to shift/extend the torque curve towards the high end of the rpm range rather than looking for ways to run even more turbo boost. Think turbo, cams, head porting, rebuilding engine with balanced/strenghtened internals and reprogramming fuel injection rev limiter to 7,000 or so, electronically controlled , reprogram fuel injection for bigger injectors/AMM, additional injector(s) or stand alone engine management system, etc.
For instance, the 900 EV-1 concept car of 1985 had 282 hp @6,500 rpm, and an entirely reasonable 246 lb/ft of torque @ 3,500. A set up like that would likely be no more harmful to the transmission and as easy to drive as a (commercially available) 'stage 1' type of upgrade giving 220 hp @ 5-5.5K, and about the same torque.
Happy Saabing,
Eric
Turbo! Team Europe
posted by 213.116.126...
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