Anybody know what the octane rating is for that other 15.0 or more percent of fuel that's inside of e85.

I'm wondering this since the only nearby gas station in my area has stated 51-83% ethanol content at their flex fuel pump. So basically I don't have access to any straight guaranteed "E85".

But I'm trying to determine if it would still be beneficial for me to run the kind that they're offering.

So for example, the other stuff that's inside of E85 that's not alcohol, is it gasoline? 87 octane?... 91? 93, 99 octane? - Can anybody answer this

Anybody that has a more in depth understanding of the composition of E85 aka Flex Fuel, please feel free to share some insight. I have an organic chemistry background so don't be afraid to speak foreign language.

Cheerz

 

Odds are it's going to the cheapest gas they've got, so probably 87 if not 85.

--Ian

 

Lol I've figured that. Based on the price of it. thx

 

My guess is the same as Ian, 87 or 85.

Empirically, it does not matter. True E85 (70% or better) has the detonation resistance of ~116 octane gasoline.

 

Yeah, I just kind of did some rough math which pretty much concluded that even if I ran their flex fuel at the lowest percentage of ethanol (51%) advertised, as long as the other percentage was 87 octane minimum, I would still have a better octane rating than running pure 93.

So perhaps it will be a good idea to run it anyway but have a flex fuel sensor.

 

I was researching E85 for my 12:1 compression engine and found that you can't rely on pump E85 to be consistent or accurate. If you really want to use E85, you're best getting it by the barrel. Definitely integrate the flex fuel sensor if possible.

 

Depends very much on your source. Pearson in Socal is garbage, E85 means "51-85%" to them. In Norcal we get Propel fuels at Chevron stations, which is extremely consistent at around 80%.

 

Pearson here in nor-norcal is 70ish
Propel and Mobil are always 80+

I've observed a significant improvement over our CA91 with anything over 30%