volumetric efficiency

noun
  1. the ratio of fluid delivered by a piston or ram pump per stroke to the displacement volume of the piston or ram
  2. the ratio of air or gas-air mixture drawn into the cylinder of an internal-combustion engine to the volumetric displacement of the piston
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012