What is Mean Piston speed of Engines?
In engine applications, the mean piston speed is a critical parameter.
Sp. it is defined as , Sp=2LN
Where L is the stroke and N is the rotational speed of the crankshaft in revolutions per minute. It should be noted that when it comes to correlating engine behavior as a function of speed, Sp is frequently a better statistic to use than crank rotational speed.
Due to resistance to gas flow into the engine or stresses caused by inertia of the moving elements, the maximum value of Sp is capped at 8 to 15 m/s. Vehicles run at the higher end of this piston speed range, whereas massive marine diesel engines operate at the lower end.