I am wondering if it is safe to use the 93 oct tunes if the gas had 10% ethonal? Or should I stick with the 91 tunes. Thanks for the help.

 

93-octane tunes are all designed for 10% ethanol, this is standard throughout the industry unless stated otherwise.

 

A lot of stations, at least here in Missouri will advertise that they are ethanol free.

 

FYI: It's technically illegal to use that in a modern street car. Obviously it won't be enforced, but there's a little factoid for you. You'll actually find you make less power than E10 93-octane too; although gasoline contains more energy per gallon, the 10% ethanol works well as a knock-quench.

 

thanks for the help guys, well I tried the 93 tune and logged it and man did I get some knock in the higher rpms. highest was 2.46 at 6023 with 23psi and leveled off to 1.76 at 7500 13psi. I may change it back to 91 oct. Does that seem high to you guys? Everything before 6000 rpm was 0 knock.

 

Semi-offtopic, but I've been wondering if anyone's ever tuned on E20 to see how it compares in knock resistance 91 or 93. It would obviously be far better mileage than E85, I just don't know how to predict the knock resistance since you don't know the octane of that 80% gas. I would assume it's just 87 for cost, but is 20% alcohol enough to make it better than 91 or even 93?

 

on a side note when I ran this 93 oct with the 91 tune I did avg 20 mpg with mixed driving.

 

I was reading something the other day about a push to switch nationwide from e10 to e15