Definition

Noun: A standardized numerical measure that indicates the resistance of a gasoline fuel to premature detonation (knocking or pinging) in a spark-ignition internal combustion engine. A higher rating signifies greater resistance to knocking.

Usage and Examples

The octane rating is a critical specification for motor fuel. * You should check your car's manual to see the recommended minimum octane rating for its engine. * Premium gasoline typically has a higher octane rating than regular unleaded fuel. * The fuel company advertises its new formula as having an improved octane rating.

Advanced Usage

• The term is often used in technical discussions about fuel efficiency, engine performance, and automotive engineering.
• It is a key factor in designing high-compression engines, which require high-octane rating fuel to operate correctly.

Variants and Related Words

• Octane Number: A fully synonymous term.
• Antiknock Index: In some regions, like the United States, the octane rating displayed on fuel pumps is an average of two testing methods and is called the Antiknock Index.
• Research Octane Number (RON) and Motor Octane Number (MON): These are the two primary laboratory test methods used to determine a fuel's antiknock characteristics. The octane rating is often derived from these.

Synonyms

• Antiknock rating
• Fuel octane

Related Phrases and Concepts

• Knock Resistance: This is the property that the octane rating quantifies.
• Fuel Grade: Often defined by its octane rating (e.g., regular, mid-grade, premium).
• Compression Ratio: An engine specification that determines the required octane rating of the fuel.

Noun

1. a measure of the antiknock properties of gasoline