E-85 what do the numbers mean

[belsie]

Here in Central Florida I have been driving app. 30 miles each way for fuel and pump sticker states minimum 70% ethanol, so far so good. Then to my delight a new RaceTrac opens 5 miles away but the pump sticker states minimum 51% ethanol!!! I am ordering a tester today but my concern is what do these numbers actually mean. Any guidance or thoughts???

 

[Boost231]

Min you will see is 70 percent or 51 percent. The higher the better. Keep it about 85 if at all possible

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[BEATAV8]

In my neighborhood I've tested Shell as low as 60% and thortons as high as 88%.

 

[Powertechn2]

Out of curiosity, how much variance is there in octane rating with the difference in E %?

I would assume the ethanol variance drastically affects tuning.

 

[BEATAV8]

Good question. I haven't seen any real data myself. My car seems to run about the same with 80-88%. I avoid anything less.

 

[turbo89]

Out of curiosity, how much variance is there in octane rating with the difference in E %?

I would assume the ethanol variance drastically affects tuning.

NO !

 

[marleyskater420]

Here in Central Florida I have been driving app. 30 miles each way for fuel and pump sticker states minimum 70% ethanol, so far so good. Then to my delight a new RaceTrac opens 5 miles away but the pump sticker states minimum 51% ethanol!!! I am ordering a tester today but my concern is what do these numbers actually mean. Any guidance or thoughts???

Do you know what kind of fuel they cut the ethanol with? As in, what type of fuel is blended with the ethanol to make the mixture that they sell at the pump?

I wonder if you would do a Specific Gravity test (Kinsler sells a Fuel Analyzer kit) if you knew the SG of ethanol, and of the gasoline they mixed it with, and thus determine what the SG of your fuel is, and by deduction know your octane rating via the amount of ethanol present in the fuel (which would be determined by the SG of the fuel).

Or am I totally off here? I could be....It has been years since I've done this...

 

[belsie]

The fuel distribution folks at Racetrac say they have no way of knowing for sure because of different ratios delivered from several locations to the retail stations??? I used the Quick Fuel tester on 10 cans I had and ranges from 80 to 90 were the average. Guess we gotta check our stash!!

 

[Powertechn2]

I guess at least they are as consistently inconsistent just like they are with the E10 % variations.