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This is as close i could get to my current car engine, it's a flex fuel and i tried the values using pure ethanol (that according to wikipedia has a RON of 108.6). Will update if I can find more details.

Yeah, you won't be able to get it 100% right as not only does ethanol have a higher RON, it also has a higher energy density (sort of, less energy per unit of fuel, but you can run more fuel for the same quantity of air, I think its stochiometric ratio is something like 9:1?)

Yeah, there is that too I am trying a few engines here but the game don't like the compression ratios used on our cars . I still find it amusing that almost all engines produced today (flex fuel) here use a compression ratio of at least 12:1 or even close to 14:1 and still can run on our gasohol (94 RON) without pinging using only MPFI since there is no car that uses DI around.

There's also the cooler inlet charge from the higher latent heat of vaporisation.