Octane rating for E85?

[FasstChevys]

How will using ethanol effect your fuel economy. It is my understand that it is almost a 2 to 1 ratio alc.to gas. if converting to alc. You need bigger jets on carb. or would need to be able to flow more fuel on fuel inj. vehicle. Wouldn't your fuel economy be about 1/2 as good as it would be with reg. gas? Plus E85 isn't much cheaper than reg. gas is it?

It's definitely not a 2:1 ratio. In many cases, your gas mileage drops by about 10%...and of course, every vehicle is different. Yes on the jets and more flow. In my area, E85 is about 35 to 50 cents cheaper per gallon.

[Packy]

My father in law is a tech nerd and he was filling me in on all of the facts about E85. Looks like we will have to change our fuel filters and lines in some cases. The 1998 models may even have to change their gas tanks out... Overall though it should be a good fuel for us to use especially with boost in mind!

[86TransAm383]

2 : 1 is the correct ratio for alc to gas. and a 105 oct. im looking forward to 12:1 com. n/a of course for the same price as 92

[FasstChevys]

2 : 1 is the correct ratio for alc to gas. and a 105 oct. im looking forward to 12:1 com. n/a of course for the same price as 92

I can guarantee you, you do not use twice as much alcohol as compared to gasoline. 2:1 is definitely not the correct ratio. The octane of E85 is indeed 105. What am I missing?

[ericwilloughby]

What you are missing is how vague the statements are. Ratio of what to what. A/F ratio of gas is 14.7 to 1. The A/F of ethanol is 7.1 to 1. So the difference between gas and AL is 2-1. It does require much more fuel capacity to run at WOT on AL. But if you don't run 100% E85 or if you can keep your foot off the floor you can use E85 on a stock auto. I've done it. 2000 SS. At 50% E85 you don't even get a check engine light. Over that % and only if you put it on the floor do you get a light because of the lean condition. I got 8% worse mileage. But that was running a somewhat lean condition. I don't have a A/F meter. Also E85 is the same price as gas in Louisville KY.

[ericwilloughby]

Here is what I cant grasp. Twice the fuel per liter of air for AL. If AL had twice the energy as gas I could see getting the same mileage. But it would also provide twice the HP. It doesn't and it doesn't. So why is there only a %10 drop in mileage and 2 % increase in HP. These figures are accurate for a non E85 car and a flex fuel car. Why?

[Goatdriver]

Ethonal is produced from the grain NOT the leaves and stalks. I know this because I farm and grow corn some of which winds up at local ethonal plants. As for octane E-85 is rated at 105 octane. As for the question on mileage I can only speak from experience and in my wife's Tahoe the mileage decreased aprox. 15% using E-85 compared to the 10% ethonal blend with an octane rating of 90. By the way E-85 has been running 40-60 cents per gallon cheaper where I live so this helps offset the decrease in mileage.

[FasstChevys]

Ethonal is produced from the grain NOT the leaves and stalks.

Not right now, but cellulosic methods and technology of producing ethanol is out there and is already happening, but not on a large scale. It could become the wave of the future, and possibly phase out corn as a feed stock in the future.