Did you ever think about this unit of measurement?
In general, the horsepower (hp) is a unit of power. It is approximately equal to 746 Watts. In particular, the brake horsepower (bhp) is a measure of the engine’s power at the crank. It is a measure of power at source before it is delivered (and partially lost) to the wheels. Remember that some of the engine’s power is lost in transmission where the gearbox, the differential and other components contribute to the loss in power. In the term brake horsepower, the word ‘brake’ refers to a device which used to load the engine to keep it running at a particular RPM. Nowadays, the brake is not used anymore. Instead, an engine dynamometer is used to calculate the output torque and rotational speed of an engine.