What does Indicated Mean Effective Pressure (IMEP) refer to in an engine?

Indicated Mean Effective Pressure (IMEP) refers to the effective working pressure generated during the power stroke of an engine cycle. It is a crucial parameter that helps evaluate the performance of an engine, as it reflects the cylinder pressure averaged over a complete cycle, taking into account the work done on the piston. Essentially, IMEP provides an indication of the engine's efficiency and output potential by relating the cylinder pressure to the power produced.

During the power stroke, the combustion of fuel generates high pressure in the cylinder, which pushes the piston down and translates thermal energy into mechanical energy. By calculating the IMEP, engineers can assess how effectively the engine converts combustion pressure into work, aiding in performance analysis and optimization.

This means that while maximum working pressure, pressures during compression, and minimum working pressures are relevant in different contexts, they do not accurately capture the overall effectiveness of pressures experienced during the entire power stroke, which is what IMEP is designed to represent.