noun (Automotive engineering: Design and performance) The volumetric efficiency of an engine is the extent to which the cylinder is completely filled by the air/fuel mixture that enters on each exhaust stroke. This measures the ability of an engine to breathe freely. ⇒ The easier the engine breathes, the greater its volumetric efficiency, and the more power it produces. ⇒ The volumetric efficiency of an engine can be reduced by restricting the airflow in and out of the engine. ⇒ Volumetric efficiency is how an engine's pumping capacity is defined.
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