NaughtyGeek

I'm trying to get a ballpark figure for what my HP is at the crank. I'm pushing 372 to the wheels with an automatic 04 GT. Can someone point me in the right direction?

devongarver

I always was told by tuners about 17-18% loss with an auto, and about 12-13% loss with a stick.

So with 372/.82 = 453.65 That an 18% loss, so you're likely around 450 ish.

cliffyk

^+1

Those are good "rule-of-thumb" numbers...

grogan

im at 475 crank hp with 358.9 rwhp. i have dyno sheets to show for it.

im in an 03 automatic

cliffyk

That's a 24% loss, which is quite a bit--how was the crank HP determined, on an engine dyno?

Mustang_NTriangle

your dreaming at 475 to the crank.

grogan

the motor was pulled out of the car and placed on an engine dyno, yes. there was a problem with the manifold (it took me 3k to figure that out) and i had decided that while it was out of the car id get true numbers on it. then when it was placed back into the car and the manifold was set straight the rear wheel numbers came in

cliffyk

Wow, that slushbox is eating up a bunch of power!

devongarver

Something's skewed....that's A LOT of parasitic loss...even my ranger with an auto was only around 19-20% loss....

cliffyk

It occurred to me that when on the engine dyno it may have been running open headers, no alternator, no p/s, no A/C, and maybe being force fed water...