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.
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 |