Horsepower figures are usually measured at the crank. Brake horsepower takes into account any parasitic losses incurred in the "system". Quick example with an automobile engine. The quoted horsepower is usually taken with the motor on a test stand, without the transmission and accessories (A.C., water pump, smog pump, mufflers, etc.) installed. Brake horsepower would be measured at the drive wheels, taking into account all the losses in power incurred by drag. Most cars loose around 30% of the engines power because of parasitic losses. Hope this helps. See ya.