does anyone know how to calculate whp to bhp? i have 320 whp on my 05 8 and wanted to see what my bhp would be....thanks.

 

This is a good question I would like to know as well.

 

Brake horsepower (bhp) is the measure of an engine's horsepower without the loss in power caused by the gearbox, generator, differential, water pump, and other auxiliary components.

So you would have to account for the power loss through the whole drivetrain and belt driven components. I would say add ~15-17% to WHP.

 

This is not that accurate but close...

(Your HP at the wheels) * (18% drivetrain loss) = Your car BHP.

So... 320whp * 118% = 377.6bhp

If there's anything wrong with this calculation please chime in guys.

 

*edited* ^^^ the guys got it.

 

its closer to 20%+

 

its all whatever. once you have modded you should only use whp

 

It depends on the dyno, the car, and a billion other things... there is no magic precent. your best bet is to ask the person where you had it dyno'ed as to his or her best guess on the drivetrain loss to thier dyno numbers

 

Hmm.. Rule of thumb for driveline loss of a RWD solid axle manual is about 15%, 20% if it is auto. I know the Subaru STI has a driveline loss of roughly 26%.

Here's an easier way to get a general rule of thumb. How much does a 100% stock Evo pull on the wheel dyno you used? You know what the Stock Evo makes at the crank, so you can get a relative idea of the loss involved and work backwards from there.

 

There is no answer, and it's not a useful statistic anyway. You have to put your motor on an engine dyno to find out. It's different for every car, and it is not linear as power increases.

 

That doesn't work either, because dynos read differently. We also know the 05s and 06s were underrated at the crank by Mitsu.

 

That's why I specified the dyno he used. But if there is no way of knowing how much crank hp the Evo comes with stock, then we're right back to the rule of thumb. So I'd say ~25%.

 

Thats pretty cool to know.

 

great! thanks for the info...unfortunately, my car got dyno'd in hawaii and i am now in nv....oh well, i guess i'm just gonna have to be happy with whp, its better anyways.

 

Please explain why your car got dyno'd in Hawaii... I assume you don't know where it got dyno'd because then we could figure out what type of dyno it is and give you an approximation. Roughly high 300's is probably a good approx.