The horsepower developed in the cylinders of a reciprocating engine is referred to as what?

The horsepower developed in the cylinders of a reciprocating engine is referred to as indicated horsepower. This measurement represents the total power produced within the engine's cylinders, based on the pressure exerted on the pistons during the combustion process. Indicated horsepower is calculated from the engine’s pressure readings and engine speed, specifically taking into account the volume and pressure of the combustion gases during the power stroke.

This concept is crucial in understanding engine performance, as indicated horsepower assists in evaluating how efficiently an engine converts its thermal energy into mechanical energy. It's a theoretical measurement that does not account for losses from friction and other factors present in the engine's mechanisms, which is why it is often higher than what is available at the output shaft.

Shaft horsepower relates to the actual usable power delivered at the crankshaft after accounting for losses, while brake horsepower measures output after friction losses and accessories' work have been taken into consideration. Net horsepower typically refers to the power output after all losses have been accounted for, providing a clear picture of the engine's efficiency in real-world conditions.