Piston Displacement Rate (PDR):

\[ PDR = 2 \pi PD N \]

Where:

• \(PDR\) is the piston displacement rate in cubic centimeters per minute (cm³/min).
• \(PD\) is the piston displacement in cubic centimeters (cm³).
• \(N\) is the crankshaft speed in revolutions per minute (rpm).