Mean effective pressure

The mean effective pressure (MEP) is a quantity relating to the operation of a reciprocating engine and is a measure of an engine's capacity to do work that is independent of engine displacement. When quoted as an indicated mean effective pressure (IMEP), it may be thought of as the average pressure acting on a piston during the different portions of its cycle.

Mean effective pressure
Common symbols	p
SI unit	Pascal (Pa)
In SI base units	1 kg⋅m−1⋅s−2
Derivations from other quantities	p = W·V−1
Dimension	${\displaystyle {\mathsf {L}}^{-1}{\mathsf {M}}{\mathsf {T}}^{-2}}$