What does gasoline octane number mean?

1 Answers
VonKayden
07/30/25 7:48am
Gasoline octane number refers to the unit of measurement for gasoline's anti-knock performance under lean mixture conditions. Numerically, it equals the volume percentage of isooctane in a standard fuel that exhibits the same anti-knock performance as the test sample under specified conditions. The determination of octane number is conducted in a specially designed single-cylinder test engine with variable compression ratio. The standard fuel consists of a mixture of isooctane and n-heptane, where isooctane serves as the standard for excellent anti-knock performance with an octane number of 100, and n-heptane serves as the standard for poor anti-knock performance with an octane number of 0. By mixing these two hydrocarbons in different volume ratios, standard fuels with octane numbers ranging from 0 to 100 can be prepared.
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