Brake horsepower (BHP) is the amount of power generated by a motor without taking into consideration any of the various auxiliary components that may slow down the actual speed of the motor. Brake horsepower is measured within the engine’s output shaft. Depending on the configuration of the engine, the point on the output shaft that is the focus of the measurement is the engine dynamometer.
The reference to this type of horsepower measurement as brake horsepower has its origins in the braking systems that were used on some of the first automobiles in the early 20th century. Many cars were equipped with a hand brake that would slow the forward projection of the vehicle. This same hand brake was also used in the manufacturing process to gauge the amount of torque created within the motor, making sure the output was within acceptable limits.
In the actual calculation of brake horsepower, it is necessary to consider the total load of the electric motor. This means disregarding any drain on the power that is due to the water pump, generator, or the gearbox that work in conjunction with the motor of the vehicle. The amount of power loss that occurs due to the action of various belts and pulleys is also added back into the base figure, making it possible to determine the true amount of pure horsepower being generated by the motor.