The motor octane number is a fuel rating that measures knock resistance under heavy load, high temperatures, and high engine speeds. It is determined in a laboratory using a variable-compression test engine with preheated fuel and advanced ignition timing. Because it simulates harsh operating conditions, the motor octane number is always lower than the research octane number for the same batch of fuel.
The spec sheet says the racing fuel has a motor octane number of 110, which is plenty for our turbo setup.
Also heard as
- MON
Do not mix it up with
- RON: RON measures knock resistance under mild cruising conditions, while the motor octane number tests it under severe load.
Related terms
MON
A measure of a fuel's resistance to detonation under severe operating conditions.
RON
Research Octane Number, a standard rating of a fuel's resistance to engine knocking.
Anti-knock index
The standard numerical rating of a fuel's resistance to premature ignition.
Knock
An abnormal and damaging combustion event where the air-fuel mixture self-ignites prematurely.