Volumetric Efficiency in an IC engine

The Volumetric Efficiency of an IC engine is the ratio of the total air drawn  inside the engine cylinder during the suction process to the amount of air which would normally be inside the cylinder of the given swept volume

Volumetric Efficiency = Total Air Present at the end of the suction process/ Air Present under ideal conditions.

The Volumetric efficiency is affected by the resistance offered to the air by the components in the air intake system such as filters and coolers.