SSCoulter

iTrader: (4)

Anyone have a good rule of thumb, or formula worked out, to determine crank HP from a given RWHP?

I realize that dyno numbers very from dyno to dyno, and that certain gear/drive train combos can also affect true HP. Just wondering if there is a fairly reliable way to calculate crank HP from known RWHP.

Thanks,

S

m1a2d3

every car is different. a six speed might be 12%. an unlocked auto might be 20%. its a hard ? to answer. theres really is no rule of thumb.

blk/slvr02ss

iTrader: (21)

RWHP Divided by 85% for a Stick car or RWHP Divided by 80% for a Auto tells Crank HP.

SSCoulter

iTrader: (4)

Ok thanks!

WKMCD

iTrader: (2)

FWIW: My build made 656HP on the engine dyno and 577RWHP on a DJ. The 15% figure works on some..not on others. As HP increase the % loss goes down.

SSCoulter

iTrader: (4)

Cool, thanks. Going to have my new motor dyno tuned and was kicking around the idea of having some HP badges made. Don't like the black Z28 factory badges on my black car, don't really want to have them in chrome, so I found a site that will custom make a HP badge. I am sure that even after I get the HP numbers I will order a conservative number for the badges, but I think it would be cool.

Thanks again.

S

SSCoulter

iTrader: (4)

http://www.westcoastcorvette.com/p-3...bers-only.aspx

I think all chrome badge in place of the Z28 badge will be sweet.

S

DynoDR

iTrader: (1)

Fixed it for ya!

brianw401

iTrader: (4)

This is very true & I have seen it more that once. It seems that the 15% / 20% rule is a guess on anything above 500 crank hp. It gets you close though. The lower the power numbers, the more accurate the formula is. Wierd !

karpetcm

iTrader: (2)

What i exactly do is im about 350 rwhp and just do 350/.85= 411.76 Hp and im 355 rwtq so its 355/.85= 417.64 Tq. Thats 15% for manual is what i usually go by and auto might be about 17-18% but some will say up to 20 depending on drivetrain and so on.