horsepower

[Mazda Ebrahimi]

Tom Cloud wrote:
> 
> I guess I'm real dumb ... thought I knew, but now I'm cornfused.
> What do the different horsepower specs mean?
> 
> Example: in MotorSport catalog is 302 SVO engine that makes
> 285 hp, but there is another with EFI, but same cam, etc that's
> rated 225 bhp.  I thought bhp was at rear wheel -- or is it
> just a different type of horsepower determination?
> 
> Tom Cloud <cloud at peaches.ph.utexas.edu>

I'm no expert at the topic, but bhp (brake horsepower) refers to power 
output of the engine at the flywheel.  This is the actual power output 
due to combustion minus losses due to friction internal to the engine, 
etc.  Could the difference between the two be the exhaust and intake 
systems?  225 sounds like the stock 5.0L Mustang engine (with emissions 
trim and all).

Rear wheel horsepower is entirely different, and while it's very useful 
for the guy working on his 1/4 mile time, it is not a very accurate 
indicator for engine performance.  I haven't checked this for myself, 
but typical drivetrain can waste about 25% of the engine's power output 
(don't quote me on that).

Best Regards, Mazda