The research octane number (RON) describes the behavior of the fuel in the engine at lower temperatures and speeds, and is an attempt to simulate acceleration behavior.

What does research octane number 91 mean?

What is octane rating? Octane rating is the measure of a fuel's ability to resist "knocking" or "pinging" during combustion, caused by the air/fuel mixture detonating prematurely in the engine. In the U.S., unleaded gasoline typically has octane ratings of 87 (regular), 88–90 (midgrade), and 91–94 (premium).

How is research octane number calculated?

The most common type of octane rating worldwide is the Research Octane Number (RON). RON is determined by running the fuel in a test engine with a variable compression ratio under controlled conditions, and comparing the results with those for mixtures of iso-octane and n-heptane.