How is engine output typically measured?

Engine output is typically measured using brake horsepower (BHP), which represents the total power output of an engine without bearing any losses from the ancillary components, such as the alternator, water pump, and exhaust system. BHP is a crucial metric because it provides a clear indication of the engine's power capability available for performing useful work, such as propelling a vehicle or generating electrical power.

Brake horsepower is derived from a measurement taken at the output shaft, usually when the engine is run at full throttle and is still able to provide power efficiently. This measurement contrasts with other measurements, such as torque, which indicates rotational force but does not directly translate to power without considering engine speed (RPM).

Thrust, on the other hand, is more applicable to jet engines or propulsion systems, representing the force exerted by the engine to propel an aircraft forward rather than a direct measurement of engine output in terms of power. RPM, while important for determining how fast an engine is running, does not provide a complete picture of the engine's output on its own since it must be combined with torque to calculate horsepower. Thus, brake horsepower is the most relevant and commonly used parameter for measuring the effective power output of an engine.