Enter the torque and displacement of an engine into the calculator to determine the brake mean effective pressure (BMEP).

BMEP Formula

The following formula is used to calculate a brake mean effective pressure.

BMEP = 150.8 * T / D 
  • Where BMEP is the brake mean effective pressure (psi)
  • T is the torque (lb-ft)
  • D is the displacement (CID – cubic inch displacement)

To calculate the break mean effective pressure, divide the torque by the displacement, then multiply the result by 150.8.

BMEP Definition

BMEP is an acronym that stands for brake mean effective pressure. The brake mean effective pressure is a measure of the total pressure that if applied to the pistons of an engine through an entire stroke, would reduce the power output of the engine.

Example Problem

How to calculate BMEP?

  1. First, determine the total torque the motor can output.

    For this example, the motor being analyzed can output a total of 55 pound-feet (lb-ft) of torque.

  2. Next, determine the displacement of the engine.

    In this case, the engine displacement is measured to be 10 cubic inches (10 in^3)

  3. Finally, calculate the brake mean effective pressure.

    Using the formula above, the BMEP is found to be:
    BMEP = 150.8 * T / D
    BMEP = 150.8 * 55 / 10
    BMEP = 829.4