brake mean effective pressure

brake mean effective pressure (BMEP)

A measure of mean effective pressure in a cylinder of a reciprocating engine. It is the average in excess of ambient pressure inside the cylinder during the power stroke. It is measured in pounds per square inch (psi), kilopascals (kPa), or bars and relates to torque produced by the engine. BMEP can be calculated if the brake horsepower and RPM of the engine are known. BMEP is that portion of indicated mean effective pressure (IMEP) that produces brake horsepower. The remaining pressure used to overcome internal friction is called friction mean effective pressure (FMEP).