am planning on doing my tune soon for february here in chicago for the e85 will there be a big difference if i tune on e85 now or when its summer and am talking about this e70blend stuff is there a big difference and do i need to retune when summer comes since the blend is supposedly different.

 

I would retune for e70. Or you can just not beat on it and drive it casually and it it shouldn't mess with your tune too much.
Why not even tune for e85 come summer time and do a 93map or something for winter?

 

i understand what your geting at but i made a appointment already and i just installed the double pumper 1200s and i wanted to know the big difference between this winter blend. and summer i ask the gas station clerks they have no idea what am talking about and am not even sure every gas station goes through the same provider and if the provider changes the blend.

 

I assume doing a tune on E70 would be more prudent since it would be more conservative than for E85.

 

Most locales will have the E85 available for significantly longer each year than the E70. Therefore, I suggest tuning for the E85 and then simply backing off the boost in E70 season.

Or, if you have a laptop and Tactrix cable, simply pull a few degrees of timing (until knock disappears) with E70 and, voilą, you have yourself a both a summer and a winter flash.

 

Exactly what I did this winter once the blends were winterized. Dropped a few pounds of boost for the last couple months. Everything is gravy.