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

Audi, Honda and Ferrari fear Mercedes have found a way to use thermal expansion and materials technology to exceed the mandated compression ratio.

From BBC ● Feb. 18, 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

And it's not only on compression ratio, but on other things too.

From BBC ● Feb. 2, 2026

This seems low, considering the compression ratio and probable leakage past their rather weak piston rings, but it is possible.

From The Wright Brothers' Engines and Their Design by Hobbs, Leonard S.