Quote:
Originally Posted by moto-mike
Lots of info on this on the forums but the basics are as follows:
7 psi will usually run as long as you'll own the car...about 1% that are safely tuned at that power level will fail for one stupid reason or another. Still exceeding OEM torque by 75%.
12 psi will run a good while, about 10% of those will fail after 30-50k miles.
15 psi (400+ WHP) will fail. Guaranteed, just a question of when. Some go a couple years, others go a few months.
Now nearly universally some knowitall will raise their hand and say they've gone 10 years and 100k miles at 500 whp on the stock motor--it's all in the tune. No, its not. It is more often just all highway miles and likely a very optimistic dyno, or possibly a creative imagination. Steel and aluminum fatigue. At stock power levels they will not fatigue until your bearings are well worn and the car is as the scrap yard. But when getting pounded with double the stress, expect 1/4 the life.
For those worried about the FA20 in the BRZ have some solace--subaru felt it was good enough as is to use in the FA20DIT at near 300 hp with some very minor changes. I disagree with Subaru that that was a good idea (we've taken apart a few) but if you don't beat on it too bad and use good fuel you should have no problems.
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I wouldn't consider heavier rods and almost 2 points less compression, a minor change. I guess it's going to boil down to having to accept lower power levels for longevity.