http://answers.google.com/answers/threadview?id=426996 Brake horsepower: (BHP)
"A measurement of the actual usable power (not calculated power)
measured at the output shaft (usually the crankshaft) rather than at
the driveshaft or the wheels. Thus none of the auxiliaries (gearbox,
generator, alternator, differential, water pump, etc.) are attached.
It is called the brake horsepower because the shaft power is usually
measured by an absorption dynamometer or "brake." This is not the
brake on the vehicle's wheels but a testing device applied to the
shaft. This instrument is applied to stop or absorb the rotation of
the output shaft and returns a value."