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octane number

Glossary “octane number” Definition:
The number representing the average blend of iso-octane with an index of 100, and other hydrocarbons with an index of 0, usually between 87 and 92.

octane rating

Glossary “octane rating” Definition:
Term used for octane number. Measurement of a gasoline’s ability to resist engine knock. The higher the octane rating, the less prone the gasoline is to cause engine knock (detonation).

octane enhancer

Glossary “octane enhancer” Definition:
Common term designating components that are added to gasoline to increase octane and reduce engine knock. Examples are toluene, ethanol, ETBE, and MTBE.

OBD-I

Glossary “OBD-I” Definition:
On-Board Diagnostics Generation I. An on-board automotive diagnostic system required by the CARB since 1988, which uses a microprocessor and sensors to monitor and control various engine driveability functions.