Quote:
Originally Posted by alphasaur
ethanol has a different stoich value than regular fuel, it has to run richer to reach stoich (9.7:1), meaning you burn a higher amount of ethanol vs gasoline (14.7:1)
If your car is not tuned for it you risk running lean
ethanol has an effective octane of ~160 in direct injection engines which is why even a blend like e30 can have a huge positive effect when tuned in a direct injection engine.
HPFP issue likely come from the Mazdaspeed community as higher than 50% ethanol on that platform can lead to "black death" of the HPFP, it's really just oil and fuel mixing and gumming up the HPFP. This platform does not that that issue. I guess the HPFP might also have to work harder since more fuel volume is needed?
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Nice explanation. I knew that higher E## gas got fewer MPG, but not the explanation behind it. According to the government study on E30 I read, a modern ECU can adjust the fuel mixture to run E30 even if the car is rated for E10 or E15. I'm not saying that's a good idea, or that it even applies to our specific cars - I'm just saying that's what a study (that may or may not have any bias) said.
So it sounds like if you had an E30 tune on a twin it would be a solid option. Probably not as much power as an E85 tune, but also probably better MPG.