compression ratio

American

noun

Automotive.

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

compression ratio British

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of compression ratio

First recorded in 1905–10

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

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

From 1 June, the compression ratio will be measured at 130C as well as ambient temperature, and from next year only at 130C.

From BBC

That means that from next year, manufacturers will be able to have engines that exceed a compression ratio of 16:1 at ambient temperature, even though this reduction from the previous limit was introduced into the 2026 regulations to make the rules more appealing to new manufacturers.

From BBC

Mercedes' rivals were pushing for the compression ratio to be measured at operating temperature.

From BBC

Audi's entry this year rekindles that old rivalry with Mercedes, and battle lines have already been drawn in a pre-season row over the rules governing the engines' compression ratio.

From BBC

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023