Recognize the rating system
US pump octane uses the antiknock index, commonly shown as the average of research and motor octane numbers. Other markets commonly display RON. Equal-looking numbers from those systems are not equivalent fuel specifications.
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Read the tune documentation
When a calibration is labeled with an octane number, establish which system the tuner means. Do not select a map using a number from an overseas discussion without checking its fuel assumptions. Ethanol content can be another independent requirement.
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Do not use a universal shortcut
There is no single subtraction that establishes every fuel’s exact AKI from its RON because motor octane also matters. Use the vehicle or tuner’s documented local fuel equivalent. A higher rating describes resistance to knock, not a guaranteed power gain for an engine that does not need it.
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Sources / references 1
- Manufacturer technical reference ↗Reviewed Oct 6, 2026
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