[Shane@DBPerformance]

You have to look at more than the A/F ratio, if you are going to try to push the car on E85. Tuning it on the worst/lowest ethanol mix and then just richening it up later when it has more ethanol in it should work ok. Tuning it on the best mix and then later just trying to fix the A/F ratio might not work so great, since you will be losing some of your cooling and knock resistance.

You can't get E100, because that would be a drinkable alcohol. They add 2% of whatever(gasoline, methanol, poo) to make it into E98, kinda of like what they do with automotive nitrous to keep you from having too much fun with it. People who are using E85 as a legal racing fuel are mixing their own and using racegas for the gas portion.

Yea, normal MN gas is the same year round with 10% ethanol, so you don't have to worry about it changing too much.

There is a simple way to test the ethanol content in gas using a graduated cylinder and a little water.

"The ethanol and gasoline levels used in producing E85 will vary by season and from region to region. Minnesota, because of its location in the northern United States, may have an ethanol content of 70 vol% in April, while Texas may have a (minimum) content of 79 vol% during the same month. The E85 blends in Minnesota will vary from a minimum of 70 vol% in winter to a minimum 79 vol% ethanol in summer. The following blending ratios (Table 1) should be used for ethanol blending in the northern tier of the United States. "

"As is the case with petroleum-based fuels and their respective engine technologies, seasonal blend adjustments are required for E85 to ensure proper starting and operation in FFVs. ASTM 5798-98A has been adopted to provide blenders the specifications needed for formulating E85.

Early fall changes are of particular importance to prevent cold weather starting problems. When supplying E85 to retail outlets, the date and the expected sales volumes of each station should be considered when determining what blend to deliver. An E85 station should NOT carry over a summer blend into fall or a fall blend into winter months. E85 blends, contrary to a popular misconception, have relatively low vapor pressure (tendency to evaporate), and a higher petroleum content is used to bring E85 vapor pressure into line with colder weather starting requirements. Adjustments may be easily achieved by adding gasoline to the existing fuel in the storage tank for the cold weather target blend. "


Season Months Blend (minimum ethanol content)

Spring March, April, May 74 vol%
Summer June, July, August 79 vol%
Fall September, October, November 74 vol%
Winter December, January, February 70 vol%