BHP at the wheel?!?!?

GhastlyTT · 10-07-2011, 03:38 PM

Because I enjoy being an educated performance nut, I wanted to clear something up (or get corrected for my incorrect thinking).

I keep seeing BHP at the wheel. Please stop saying it

Brake Horsepower (BHP) is a measure of horsepower at the crank before drivetrain loss.

Wheel Horsepower (WHP or RWHP or True HP or Effective HP) is a measure of horsepower after drivetrain loss measured at the driving wheel.

It annoys me as much as people saying RPMS, but not nearly as bad as people that type in all caps!

Ok, thanks for reading. Enjoy the ride.

boostedbb6 · 10-07-2011, 04:04 PM

190ish at the crank and 180ish at the rear wheel. we all know the difference. after that its just a matter of 'power adders' and proper tuning. dynos will all show different numbers.

GhastlyTT · 10-07-2011, 04:16 PM

Quote:

Originally Posted by boostedbb6

190ish at the crank and 180ish at the rear wheel. we all know the difference. after that its just a matter of 'power adders' and proper tuning. dynos will all show different numbers.

I think you missed the point of my thread. I know the difference, but there are many on here that keep referring to them as one of the same.

Brake Horsepower and Wheel Horsepower are two different measurements. I'm simply pointing this out in hopes that the next guy to post a dyno result refrains from posting something along the lines of "I made 178bhp at the rear wheel!".

Porridgewog · 10-07-2011, 04:55 PM

Fair point. I shan't make that mistake again.

boostedbb6 · 10-07-2011, 06:17 PM

MY POINT IS THAT...oh yeah you don't like caps either. Well, if anyone is talking about numbers, they are usually talking about numbers achieved on a dyno (wheel) so the only crank number that would ever be discussed is the claimed factory 193. Nobody is going to say they gained 20hp at the crank from an exhaust. Its implied that we extimate wheel hp gains/losses.

**Karlb** · 10-07-2011, 06:54 PM

Quote:

Originally Posted by GhastlyTT

"I made 178bhp at the rear wheel!".

what if they calculated back from RWHP to BHP to make that statment???

yzfr1mike · 10-10-2011, 09:24 PM

You hafta be an engineer!! LOL

Same here!

I think others understand that we are talking of HP improvements at the wheel, as this measurement technology is available and affordable, especially compared to mounting the engine to a dyno stand and measuring the crank HP. Tell me if I am wrong, but I bet the factory measures the engine HP at the sprocket and uses the gear transmission efficiencies to calculate the HP at the crank. This is not an easy thing to measure!

Mike