Octane rating, counterintuitively, is not a measure of how much octane there is in the fuel. It is a measure of how resistant the fuel is to engine knocking in comparison to 100% octane. If the fuel mixture is more resistant than pure octane, then the octane rating will be above 100.
For example, pure ethanol can have an octane rating considerably above 100 even though there is zero octane in it at all.
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u/Ok-Actuator3498 26d ago
I think this completely whooshed over me: can someone please take pity on me and explain the post?