Mean effective pressure

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	${\displaystyle {\mathsf {L}}^{-1}{\mathsf {M}}{\mathsf {T}}^{-2}}$

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.^[1] Despite having the dimension of pressure, MEP cannot be measured.^[2] 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. When friction losses are subtracted from the IMEP, the result is the brake mean effective pressure (BMEP).