I have a heads/cam car that dyno'd 392rwhp. I was told that i lose some power through the stall and gears. I have a yank 3200 stall and 3.73's. Also, the dynograph shows the temperature outside to be 108 when the tune was done (it was over the summer) and i don't know if the tune was corrected or not.

If this is true, how much power should i REALLY be making?

 

You don't lose power because of stall speeds or different gears.
As long as the dyno operator put in the right gear ratio and tire size you're going to lose the same power as any other automatic set up. You lose around 20%.

So 392 rwhp would come out to approx 470 fwhp.

 

Who cares about whp. It's all about the 1/4 times!!!

 

your power through a stall converter gets masked on the dyno because a dyno records speed over time to determine power rating. with a converter due to the slip ratio you mask hp on the dyno. for instance on my 01 t/a bone stock it put down 310/305 after my 3000 stall it put down 278 but i went .9 faster through the 1/4 mile.

 

Exactly what predator t/a said.

My car put down 348 RWHP and 353 RWTQ on the stock convertor and on my FTI 4000 stall it only put down 320 and 324. The only change was the convertor. But as he also said it picked up alot in the 1/4. Alittle more than .3 on my 60' times.

 

Dyno of an A4 doesn't tell you the real story if you look
at RWHP vs RPM.

The whole idea of a performance converter is to put
you onto peak HP for more of the gear duration. That
is of course if you can stand the drivability. Usually a
compromise of some sort is made.

If your HP peak is 6000 and you are at 5500-6500 the
whole gear through, you're way better off than if you
got hauled back down to 4000 on every shift. 30-40%
better at the low end of it fading to a wash at the
top end. So maybe call it 20% improvement in total
energy put to the platform.

Now a devent converter unless it's stupid loose will
be giving you better than 90% efficiency and 95%
to 97% can readily be had off the shelf. So you give
away 5% to pick up 20+%.

If people looked at dyno charts of RWT vs MPH or
RWHP vs MPH, this would show what you're picking
up. With a proper converter, more than half of the
RWHP vs RPM dyno chart is irrelevant.

 

In talking with engineers I have been told that its normal to loose nearly 20 percent with automatics and 17 percent with gear drive trans. Good luck

 

Hi,
stall and gear will get you there faster. How much depends on driver and car. Usually a stall is worth .3 to.5 give or take .........gears 3.23 to 3.73
about .2 to .3..this is for example only and not etched in stone.racing is about how fast you get there........i hope this helps and good luck with the project. Have a blessed day..........jim
PS: I CONCUR WITH MONTHY 18/22% WITH TIRES/GEARS/A-4.