Which measurement indicates the power of an engine?

The measurement that best indicates the power of an engine is horsepower. Horsepower is a unit that quantifies the output power generated by an engine, specifically how much work the engine can perform over time. It's a direct measure of the engine's capability to do work, such as accelerating a vehicle or powering machinery.

Displacement refers to the total volume of all the cylinders in an engine and can influence how much air and fuel the engine can consume, affecting overall power potential but not directly measuring output power. Engine size, while often used colloquially to refer to the displacement, is more general and does not provide a clear measure of power. Torque measures the rotational force produced by the engine, which is also essential for understanding performance but does not equate directly to power without considering engine speed (RPM). Therefore, horsepower is the most appropriate metric for indicating an engine's power.