I have just read the following in Rockauto's monthly newsletter:

E85 fuel is allowed to contain between 51 percent and 83 percent alcohol which means the octane rating for each tank of gas may vary significantly. Engines need to be able to adjust ignition timing, fuel flow, air intake and other parameters to match the octane of the fuel in the tank or the engine will run poorly and/or eventually be damaged by knock (noise when fuel ignites at the wrong time).

If this is true, it is a shock! I always though E85 had 15% ethanol!

 

E85 is an abbreviation typically referring to an ethanol fuel blend of 85% ethanol fuel and 15% gasoline or other hydrocarbon by volume.

This fuel is intended for special flexi-fuel cars and is unsuitable for regular petrol cars.

In the United States, the exact ratio of fuel ethanol to hydrocarbon may vary according to ASTM 5798 that specifies the allowable ethanol content in E85 as ranging from 51% to 83%. This is due to the lower heating value of neat ethanol making it difficult to crank engines in relatively cold climates without pre-heating air intake, faster cranking, or mixing varying fractions of gasoline according to climate. Cold cranking in cold climates is the primary reason ethanol fuel is blended with any gasoline fraction.

 

Its the other way around Greg. The number is the ethanol percentage, not the gasoline percentage. So the E10 that is ubiquitous in the US is 10% ethanol, 90% gasoline. E5 is 5% ethanol, E85 is 85% ethanol, and so on. I believe that the number is the maximum percentage, but I'm not sure.

 

If you were to drive on pure ethanol, you would have to inject 1.5 times as much to get the same energy value and the correct mixing ratio.

With petrol this is 1: 14.7, with ethanol 1: 9.0

 

Greg, I run ethanol in my turbo LS powered S3. The fuel allows me to run more boost and advanced ignition timing than on 93 pump gas, and keeps the engine safe due to higher octane and ability to resist detonation. It also is usually cheaper than standard pump gas - I just paid $2.73/gal. This is partially offset by the increased consumption (about 30% higher), which also requires a fuel system with more capability (pump, injectors, etc). As mentioned, the ethanol content can vary between stations and seasons; for this reason I run an alcohol content sensor (flex fuel sensor) which samples the fuel and automatically updates the ignition timing advance and air/fuel mixture to compensate. Pretty cool stuff.

 

Not if the engine adjusts itself which the flex fuel sensor will do. Roughly most engines give 10% more power but high compression/ turbo charged engines gain more than that!
Using E85 on my F150 4x4 V8 I lose as little as 2 mpg. From pure gasoline (100%) normal commute fuel mileage is around 22 mpg. Drops some in below freezing weather.
But the reward in smoking tires is worth the difference. My pickup is brisk. But with E85 I actually smoke the tires, it accelerates so fast.
I still use mostly E85 because there are times when the difference between E85& Regular 10% ethanol is nearly a dollar a gallon. Making E85 a real bargain.
It does two other things. It prevents the normal fuel deposit on the backside of the intake valve.
and keeps the whole combustion chamber clean ( including the spark plugs and injectors). ( it’s a wonderful cleaning solvent)
The down side is I change the oil at 4000 miles instead of 5000.
PS, turbo chargers really love it. As does high compression. ( ethanol has about the equivalent of 105 octane).
Oh, It also runs cooler. Pulling a heavy race car trailer up the mountains. I used to watch the gauge climb up into the chew on fingernails region. Not with E85.

 

you can use it on your Jaguar•••• If you add a fuel sensor and a way for your ECU to adapt to it.
Oh, yes you will need the earlier injectors which have the capability to squirt the added amount of fuel needed.

 

Chiming in: I fill my MR2 Turbo up at the local H-E-B (Texas grocery chain) and it says “minimum 70% ethanol content” on the pump.

The first time I filled up after the conversion, I hooked my computer up to the aftermarket ecu and the ethanol content pretty much dead on according to the GM flex fuel sensor.

I personally would not worry too much about E85 being lower than 80%, because as prior posts have said, ethanol is far cheaper than gas. A fuel supplier/gas station would be cutting into their already tight margins if it contained more gasoline and less ethanol.