Anyone know what grade of gasoline is typically blended with ethanol to get E85? Just curious because the company that runs my local E85 station says they blend the ethanol with regular (87 octane) gasoline. Was hoping they would have said premium.

 

I always assumed 87. I have noticed some places seem better than others. In the winter the stuff I get from Kwik Trips doesn't knock as easily as the stuff I get from Holidays. Holiday is always 68% in the winter and Kwik Trip is 72%. In the summer they are the same though. I think they both mix 87 oct.

 

search E85 octane ratings. so far i have seen 100-105. this is a quick quote i saw...
"Ethanol is an excellent, clean-burning fuel, potentially providing more horsepower than gasoline with a higher octane rating (over 100) and a cooler burn temperature than gasoline"

 

OK that has nothing to do with the OP question. e85 is 85 % ethanol and 15% gas.

He asked what octane the 15% of gas is

 

I've always heard 87 octane.

 

MrFred,

I don't think it really make a difference. E85 is usually quoted as 105 octane. Are you thinking that if they used, say, 91 instead of 87 the octane rating of E85 would be even higher? I don't think that minute amount of difference in that 15% of the total mix would be enough to change the overall E85 octane rating more than negligibly.

Even if it were, what would 105.2 octane E85 do that 105 octane E85 can't do? At that level, I don't think the difference would be measurable.

 

Even though gasoline makes up only 15%, 87 octane is fairly unstable, and I'd bet that the use of premium instead of 87 octane would help substantially with knock resistance. However, since it appears that everyone mixes with 87 octane, there's nothing that can be done about it.

I was also concerned with the possibility that a variety of grades were used depending on supplier, and my local E85 supplier was using the lowest grade. Didn't like that idea. Now that I know everyone mixes with 87 oct, I'm fine with the situation. :-)

 

I believe it is 87. Heres the thing, a friend of mine somehow got ahold of a spreadsheet and listed on it was the dates and percentages of the ethanol being supplied to stations all over the east coast. It listed a gradual change in ethanol content (from 70% to 85%) and he told me that we only just recieved the full 85% here in philly a few weeks ago..I will try to post this up shortly.

 

I suppose to anyone running a true flex fuel vehicle it would not matter.

However, for anyone who is tuned to a specific E?? mix, they would certainly prefer the same mix all the time.