friction mean effective pressure

friction mean effective pressure (FMEP)

That part of the indicated mean effective pressure (IMEP) used to overcome internal friction in a combustion chamber of a reciprocating engine. The difference between the IMEP and the brake mean effective pressure (BMEP) is the FMEP. The FMEP and the BMEP provide a convenient means of representing pressure limits or rating engine performance throughout its entire operating range.