<font face="Verdana, Arial" size="2">Originally posted by Louis200:

**Naji is right, its your whp times 1.15. **

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Actually, I think NoVTECSER is right. Assuming 15% drivetrain loss, I think it's wHP x 1.18.

Algebra:

WHP = CrankHP x (1 - LossPercentage/100)

...Therefore

CrankHP = WHP / (1 - LossPercentage/100)

So assuming 15% drivetrain loss, WHP/(1-0.15) = WHP/0.85 = WHP x 1.18. You can't just add 15% to 100% and multiply, otherwise it will come out wrong. Remember, you're "back-calculating," based on a loss of the original number.

By the way borguesian, another point about HP gains per modification is that you have to remember that some of the power gain figures are listed as peak gain, not gain at the HP peak. For example, the peak power gain with S4 cams on a 1994+ SR20DE is ~30 HP according to SCC. This doesn't mean you can throw a set of S4s in the engine, and go from 140 HP to 170 HP - that HP figure is actually at 7300 RPM. Your gain at the peak would be more like 10 HP or so.

Sorry for babbling, heh.