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A comment on How does a gas pump know to shut itself off? (1981). Parent comment

Re:How does a gas pump know to shut itself off? (1981) by jakogut on Sunday October 11, 2020 @11:57AM (#24746648)
> some engine configurations need a higher octane fuel in order to combust the fuel completely

This is incorrect. Higher octane ratings mean a fuel can withstand more compression before detonating. Pre-detonation, or "knocking", where an engine experiences detonation in the cylinder before top dead center can cause severe damage, so higher octane is used with higher compression engines. Lower compression engines see no benefit.

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Re:How does a gas pump know to shut itself off? (1981) by TheRealDunkirk on Monday October 12, 2020 @11:49AM (#24755664)
If the fuel pre-ignites, proper flame propagation will be thwarted, and the fuel will not be burned as thoroughly, leaving residue, and exhausting (albeit tiny amounts of) fuel. Sure, I put the cart in front of the horse, but I can always count on HN to point out the pedantic.
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Re:How does a gas pump know to shut itself off? (1981) by jakogut on Monday October 12, 2020 @12:06PM (#24755870)
Reading this again, you're right, it was a little pedantic. This is one of those topics I feel is just rife with misinformation, so I tend to jump on explanations that don't seem correct at first glance.
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