A Convenient Technique for Determining Comparative Volumetric Efficiency

The measurement of volumetric efficiency is discussed, with particular attention given to the design of surge tanks to smooth the inlet flow pulsations. It is shown that smoothing the inlet flow can be impractical for single-cylinder research engines. A simple and convenient method of characterising volumetric efficiency, based on in-cylinder pressure variation, is discussed, and practical implementations for both motored and firing engines are described. The method is extremely useful for the comparison of different manifold configurations or the assessment of other factors affecting volumetric efficiency.