compression ratio

American  

noun

Automotive.

1. the ratio of the cylinder volume enclosed by the piston at its outermost position to the volume enclosed by it at its innermost position.

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compression ratio British  

noun

1. the ratio of the volume enclosed by the cylinder of an internal-combustion engine at the beginning of the compression stroke to the volume enclosed at the end of it

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Etymology

Origin of compression ratio

First recorded in 1905–10

Example Sentences

See Examples For:

compression ratio

Formula 1's governing body the FIA said on Saturday that a change to the way the compression ratio was measured would be introduced on 1 June, with a further revision for the 2027 season.

From BBC ● Feb. 28, 2026

Off track, one of the main focuses of pre-season has been a row between the engine manufacturers over the rules governing the engines' compression ratio.

From BBC ● Feb. 20, 2026

Because their rivals believe they have found a way of exploiting the rule restricting the compression ratio - a measurement of the cylinder displacement between the two extremes of the piston stroke - to 16:1.

From BBC ● Feb. 20, 2026

Audi, Honda and Ferrari fear Mercedes have found a way to exploit the way materials expand with heat to have the engines running to a higher compression ratio when the car is on track.

From BBC ● Feb. 9, 2026

“An object of my invention is to automatically regulate the compression ratio in an engine inversely to the speed....”

From The First Airplane Diesel Engine: Packard Model DR-980 of 1928 by Meyer, Robert B.