N·m
cc
Result
BMEP14.21 bar
How it is calculated, with your numbers
- BMEP
bmep = 2 × π × (cycle / 2) × torque / (disp × 0.000001) / 1000002 × π × (4 / 2) × 113 / (999 × 0.000001) / 100000 = 14.21 bar
Working uses the metric units the formula is written in.
- torque Torque (N·m)
- disp Displacement (cc)
- cycle Engine type
- bmep BMEP
What it means
BMEP is the steady pressure that would have to act on the pistons during every power stroke to produce the measured torque. Because it divides torque by displacement, it lets you compare a 400 cc single with a 1,000 cc four on equal terms.
A four-stroke fires each cylinder every second revolution, which is why the formula has a factor of 2 for four-strokes and 1 for two-strokes. Naturally aspirated road engines typically land somewhere around 10 to 14 bar at peak torque.
Assumptions and limits
- Uses brake (output shaft) torque. Rear-wheel dyno torque gives a lower figure because of drivetrain losses.
Sources
- Heywood, J. B., Internal Combustion Engine Fundamentals, McGraw-Hill, 1988.