Dumb Question

[JustALilBit]

Whats the difference between bhp and whp?
What do they both stand for?
Thanks for the cooperation

[Khyron]

Re: Dumb Question

Wheel horse power, dyno measured. 12-15% lower than bhp due to drivetrain loss on a Dynojet, closer to 25-30% on a mustang dyno.

Brake horse power is crank/without the drivetrain.

Pretty sure that's right.

[Kor]

Re: Dumb Question

Yeah as Geoff said, bhp is brake horsepower and it is basically how much horsepower the engine makes if you had it out of your car and just hooked up to measure it.

Once the engine is in the car, the weight and friction of the transmission and axels and all that actually reduce how much power is transmitted to the wheels. So if you measure the horsepower by how fast the wheels move, then its less.

Generally its 12-15% difference between bhp and whp. Automatics are more different than manuals.

If your friend says he dynoed his car at 200whp then it is more like 230bhp

If you are comparing cars though, what really matters is power to weight ratio. whp/lb

[Khyron]

Re: Dumb Question

Wheel horse power, dyno measured. 12-15% lower than bhp due to drivetrain loss on a Dynojet, closer to 25-30% on a mustang dyno.

Brake horse power is crank/without the drivetrain.

Pretty sure that's right.

Just cause my edit failed: All-wheel drive cars have a much bigger difference - a 300HP WRX might only be putting down 220HP to the wheels because the drivetrain leeches much more power. Same with automatic trannies.

So when VW says the 1.8T is 180 bhp, you'll only see ~160 whp on a dynojet, ~140-150 whp on a mustang dyno.

[Stonewall]

Re: Dumb Question

I believe brake horse power is also measure with no accessories on, ie alternator etc.