IIRC, E85 is about 100-105+ octane depending on the mix… And works great for boosted applications…
It keeps the air temperature low which keeps air density up and fuel to air ratio changes little.
The air fuel ratio of gas is 14.7:1 where as E85 is 9.7:1 therefore requiring about 25% ish more fuel… But yes, way cooler intake charge…
But it’s all about the power….
Octane doesn’t make power, if your engine is designed to run on 90 octane then anything above that octane is not making more power (including race gas and E85) however it will raise the pre ignition resistance to the engine… Matter fact if your vehicle uses a knock sensor and you run the wrong octane rating then the computer will pick up the preignition and adjust the ignition timing accordingly… Meaning if your engine run X total ignition timing and and X octane and you raise the octane rating then the computer will read the knock sensor feed back and advance the timing, if your vehicle runs best on X ignition timing and you advance the timing all you are doing is reducing power and fuel milage, same for running lower octane then required, the computer will retard the timing and that could/will cause spark knock unless the vehicle is designed to run on both…
“The octane rating of a fuel is a measurement used to indicate its resistance to engine knock. A fuel with a higher octane rating will have more resistance to knock. Another way of thinking about this is how much compression that fuel can handle. A higher octane fuel can be compressed (along with air) more without detonating as a result of the heat from compression.”
This is dyno pulls from Engine Masters (Westech) on an engine built to run on 91 octane, now in real world under the hood on a hot day conditions the engine would not live on 87 octane… lol
Engine Masters also tested E85 for about the same power as shown…
Now on a boosted engine where the air intake temp is super heated vs N/A then E85 makes way more power due to lowing the intake charge a lot…
Link to quote above…