Bumping this topic to throw in some info via Ford.
Stoichiometric air/fuel mixture for pure gasoline: 14.7 units air : 1 unit of fuel
Stoichiometric air/fuel mix for E85: 9.8 units air : 1 unit fuel
Upsides of ethanol: reduced emissions, requires less air (LOL because that's the limiting reagent), combusts better and thus burns more cleanly, creates more power (yes, this is straight from Ford's training program), has an octane of about 96 in E85, can be used to raise octane level more cheaply.
Downsides to E85: requires special materials that resist ethanol, is less efficient than gas due to the 9.8:1 ratio, can cost more, subsidizing corn is stupid.
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