If you tune w/E70 and not adjust anything AND the A/F's don't lean out past 12:1 or whever "you're" comfortable with then I see no reason not to just leave it when running E85. E85 is higher octance which allows you to run leaner A/F's and more timing and boost etc...so I would say no problems?

 

E85 is much more than just the octane rating. The fuel outperforms 110 leaded and i've heard it ouperforms C16 which is 117 octane...

 

i was just keeping it basic....

 

[QUOTE=ill_take_one;6900473]Sounds like the best way is to start with E85. Then during the cooler months, when the ethanol blend is lowered, you'll run a bit richer. Probably want to turn the boost down a couple psi as well.

I unfortunately won't have that option being I need to get tuned really soon and we still have E70 according to the blend schedule out there. I think what I'll do is get another refresher tune once we get E85 during the summer months.

Someone correct me if I'm wrong![/QUOT

Have any of you actually changed the blend? For example....

lets say we add 1 gallon of 91 (I live in california) this will make the 105 octane e85 into 104 octane approx. if we add 2 gallons it goes down to 103 octane approx. Here is one of many octane calculators out there and we will strongly assume e85 is 105 octane as some pumps actually have a sticker listing the octane.

Anyway as long as you don't mix too much gas your fuel trims will go into a minus and remove the added fuel as the mixture will become rich. I strongly believe that if you are tuned for e85 on the ragged edge you might need to decrease boost and change the injector scalings. I run a conservative tune and have been testing adding regular gas to e85 specifically to lower the fuel volume so I can remain on single fuel pump when I install FP Red and turn up the boost.

 

Ocane calculator links

http://www.bazellracefuels.com/Calcs/OC1.htm

The third one down on this link seems to be the most convenient

http://www.easyperformance.com/Tech_...d_Content.html

You could have 100 octane e85 and gas blend and add back abut 10% of your global scaling. This could help someone who is maxing out their injectors. Granted the tune would have to be less aggressive.

PS I realize this is slightly off topic

 

The beauty of ethanol is it's ability to perform safley over a larger AFR window then gasoline.. Although it's a good idea to keep an eye on on AFR's, for the most part you can tune timing beyond MBT on a low ethanol contant (70%), at least that is what I have seen.. Although if you run too rich or too lean things can go south with a very agressive timing map.. If I were to guess I would speculate that at the same airflow and temp ect. you will see about a .7 maximum difference in afr (gasoline) between summer and winter blends..

Needless to say I don't sweat the mixture too much since I know where my tune is at and I know what is not safe for the engine

 

Good thread

 

Cool, i had these questions, i will be tuning on e85 soon but being in WI it seems like we are on E70-75 most of the year so i will tune on that. It seems like 11.5-12.0 is a safe AFR to run with aggresive timing? I have a AEM wideband and an egt gauge so i should be able to keep things in check. 1650-1700 still about the max egt you want to see?

 

FWIW, it may be worth contacting a few gas stations to find out what they're selling. In Denver, I called around and found one station that blends their own E85 and it's true E85 year-round.

This gas station also offers the full line of Sunoco race fuels (incl. 100oct at the pump), so its not your average corner store. If you have a place local that stocks race gas, they'll understand why you're asking if its the same.

Dave