carlsbad

Whats the Stock Z06 RWHP?
How do you calculate RWHP to engine HP??

zeevette

Stock '02-04 ranges from 340 to 365, depending on so many factors, it may as well be voodoo. Dynos/operators can say just about anything they want, depending on circumstances/motives. As far as calculating flywheel numbers to, or from RWHP, there isn't any method short of pulling the motor to run on an engine dyno, and with the exact (which is impossible) parameters, then running it on a chassis dyno, and figuring the percentage of loss. Sorry about the run-on sentence, but it really is just conjecture. Maybe somewhere between 8-20% loss? Definately not a scientific method, with all of the variables.

AU N EGL

for a good estimate use 15% for manuals and 20% for automatics

MillertimeZ06

I always used 15% to guesstimate.

tramminc

450rwhp + 18* (percent) = 531hp
531hp - 15* (percent)= 451 rwhp

is what I've been using for years, and it's never let me down.

c6ZR1 638hp - 15* = 542.3 rwhp, many of those cars dyno at that number.

zeevette

I'm skeptical of any cut and dried percentage, but this number's as good as any.

GM Fan

Pretty sure I've seen someone in the know at GM state something about 12-13% loss to the rear wheels w/ a standard GM V8/T56 setup. I think that may have even specifically been w/ a vette but I'm not sure anymore.

That seems to give about the right results for most cars that you can actually trust the factory rating on. GM seems to have an affinity for underrating in alot of cases too so...

ctusser

12-13% seems to be more accurate for these cars.

In fact a top tier tuner uses the formula: RWHP / .88 = approx flywheel hp.

For example a stock Z06 dynos at 357rwhp/.88 = 405.7 at the flywheel; which is in the ballpark of the factory specs


Say a factory C6Z comes in at 445rwhp/.88 = 505.7 flywheel which is also pretty close to a lot of posted dyno runs I've seen on those cars.