Mean Piston Speed Calculator

This calculator will determine the "mean" piston speed for a given RPM. Mean piston speed is the average speed of a piston within a rotation of the crankshaft, or equivalently, the average speed between Top Dead Center (TDC) and Bottom Dead Center (BDC) and back again. Mean piston speed is much lower than maximum (peak) piston speed.

Mean Piston Speed
 Stroke inch mm Enter RPM rpm Mean Piston Speed ft/min meter/sec

At any given RPM, piston speed changes constantly as a function of crankshaft angle. The piston accelerates from zero speed at TDC to max speed and then decelerates to zero speed at BDC. Then it does it again in reverse. The distance between TDC and BDC is the engine's stroke, and mean speed is the average speed within this distance traveled. The peak or maximum piston speed occurs somewhere mid-stroke, although NOT at 90 degrees crank angle nor at a 90 degree rod angle (common erroneous assumptions.) Mean piston speed is a simple calculation and a basic indicator of engine stresses, however far greater insight into bottom-end dynamics is provided by calculating instantaneous speed, acceleration and position as a function of crank angle.

Examples of Mean Piston Speeds

Engine Type Mean Piston Speed Stroke Max RPM HP Description
ft/min meter/sec in mm
Pro Stock NHRA 6804 34.6 3.55 90.17 11500 1500 500 cu-in naturally aspirated gas
Top Fuel dragster 6375 32.4 4.50 114.30 8500 8000 500 cu-in supercharged nitro
F1 V8 circa 2006 5219 26.5 1.566 39.77 20000 750 2.2-liter V8 naturally aspirated gas
F1 V6 circa 2014 5217 26.5 2.087 53.00 15000 760 1.6 liter turbo gas w energy recovery
NASCAR Sprint circa 2013 5092 25.9 3.25 82.55 9400 870 358 cu-in naturally aspirated gas
Small block Chevy street rod 3770 19.2 3.48 88.39 6500 375 350 cu-in naturally aspirated gas
Bugatti Veyron 3729 18.9 3.39 86.11 6600 1001 7998 cc W16 quad turbo
IndyCar circa 2014 3055 15.5 1.528 38.80 12000 675 2.2 liter twin-turbo V6 ethanol
BMW 535d diesel 2917 14.8 3.50 88.90 5000 255 3.0 liter turbo inline 6
Briggs & Stratton utility 1462 7.4 2.437 61.90 3600 5 12.56 cu-in gas single cyl