^^just continuing a bit…so the chemical associated with autoignition resistance or anti-detonation is iso-octane, which we just know as octane. it’s reverse-logic: heptane is the chem that actually ignites and iso-octane does the opposite. so when you get 87 ref fuel that means you have 13% burnable product.
that’s why when your comp ratios go up, you go higher on octane so you have less ignitable substance to keep things stable and not as hot. now if you keep pressure constant and change ignitable volume %, when you have less heptane, the explosive stuff, you should lose a bit i suppose unless there’s something i’ve forgotten.