Originally Posted by CdnoilRAM
In natural aspirated applications, a non-ethanol gas burns more efficiently because it has a faster burn wave and ethanol requires a higher ignition temperature to burn, so it really is a later second burn wave in the chamber. Also, ethanol has a lower BTU rating compared to regular gasoline, which means it requires more ethanol to create the same amount of power as regular gasoline.
That said, since your injectors are factory scaled for regular gasoline you'll see a decrease in mileage because you're replacing 10-15% of the regular fuel with a slower and less volatile fuel, so you won't make the same power per combustion cycle.
If you run forced injection, scale injectors, or tune specifically for ethanol, then you can advance timing a lot more compared to regular gasoline because of the slower burn wave, which means less potential for detonation/pinging.
Thanks for the information. I do have a Superchip tuner for my Lincoln and I have it tuned for 93 octane performance mode, but I do not know of any way to tune for Non Ethonal vs Ethonal 10%. I think the onboard computer does this automatically because when I first changed over to 93 octane non ethonal, I could smell gas when I first started the engine, but now it has corrrected it's self and I don't smell the gas any more.
For my 2012 Ram R/T Hemi, I have a D/S Trinity tuner on order and will tune it for 93 octane performance also. I never noticed any fumes from the Hemi, maybe it computes faster than the Lincoln. I get about 18 mpg average (town/Highway) with my 2011 Lincoln Navigator 5.4L and my Ram R/T 5.7L. I think this is pretty good for both vehicles. If you really put your foot in them, they both get less MPG.