The displacement of an engine is a measurement of how much air can flow into all of the cylinders and be mixed with fuel. It is calculated as the volume in the cylinder from the piston’s lowest point to its highest, then multiplied by the number of cylinders.
For example, a 3.0L engine can hold 3.0L of air-fuel mixture in its cylinders. Displacement on older vehicles is often referred to in c.i., or cubic inches, with liters coming into use in the 1970s and becoming universal today.