OK so its winter time here in NY and i know this means that the E85 that they sell is most likely E70. My question is if i get my car tuned on E70 adn the tune is not that aggressive considering it is my DD and i dont need as much power as i can get what will happen once the blend becomes more ethanol based in the summer

Would my A/f lean out considering that there is less Gas content in the mix so should i tune on the richer side for e70 so when it goes back to E85 i am safe

 

You're asking what would happen when you put E85 in a tank when you're tuned for E70?

I would compare what happens when you tune for E0 (gasoline) and then put in E100 (ethanol). Let's say you have 1 part gasoline and 14.7 parts air. Now let's say you replace that 1 part gasoline with 1 part ethanol. Ethanol and 9 parts air will be at stoich, but you're left with 5.7 parts air, making you very lean.

Assuming that this relationship holds between E70 and E85, you should tune on the rich side to be safe. However, I'm not familiar if the ECU has an air fuel mix table that corrects for slight variances in the fuel.

I'd be more worried about injectors failing with corn juice anyway.

 

I have upgraded injectors im going to have to talk to my tuner just figured id get a basic idea

 

this is why 93 is the more logical if you live in an area that has colder climates