You're getting there. As far as I know it changes the timing, and also injects more fuel. FFV motors have larger injectors (30lb vrs 24lb?) to get the extra fuel in. Basically the idea is ~30% less power by volume, but you make it up by being able to put 140% of the volume in the same cylinder and burn it.

Here's one of the best write ups I've seen, but it is for a conversion.

http://www.corral.net/forums/showthread.php?t=826071

I would love to see a bone stock F-150 on the dyno with 87 then with E85 back to back and see the real world difference. I think 5% may be optimisitic. However, anyone who's saying you'll get a performance decrease is just plain wrong.

 

I use Mobil1 synthetic with a quart of Lucas oil stabilizer and change the oil every 5k miles. I can tell that towards the end of that interval my mpg suffers so there's more to the equation than just using longer oil change intervals. FWIW

 

FWIW you can get 5K on your Mobil1 without the Lucas unless all you do is short trips that do not allow your engine to reach full temp.

 

With higher octane, the knock sensors allow the timing to advance more, therefore more power.

 

It will only increase your power 'IF' there's more 'usable' energy in the fuel for the given RPM range you're using.

 

More power than if it tryed to run like it does on regular gas anyway.

 

I'm guessing that it would probably run about the same as if you were using 93 octane premium gas, but it will get considerably worse mileage because it will be dumping a lot more fuel in.

I used to have a 89 Beretta with a 2.8 V6 and 5 speed - I ran a test - I got 29 mpg on the highway with 87 and 32 mpg with 93, and it performed noticeably better on 93. It did have a knock sensor. My logic tells me that with 105 octane E85 and a knock sensor, the performance has to be better than on 87 octane pure or E10 gas if the thing is tuned to take advantage of the higher octane (FFV engines ARE tuned this way, right?). Of course, mileage should be less due to the wide difference in stoichiometric air/fuel ratios.

 

That was my write up over on the corral. I've just recently made an update. Basically my 18 year old fuel system is still holding up well to almost a year of E85 use.

As far as the power on a FFV, everything else being equal such as timing and Lambda readings (A/F), the E85 should make more power because Ethonal is oxygen bearing, that means it brings it's own O2 to the party. Just look at the chemical formula for Ethonal

I wish I could run my 03 Expy on E85, I've even considered trading it on a FFV, but it is paid for and .02 cents a mile will take a long time to absorb in a new car payment.

But I would like to see what happens on the new FFV F150's that have a tuner on them. It seams like most people report gas milage increases on the 93 Octane tunes, but you because of the price differernce in premium, it cost more per mile to run that way. But what if you run a 93 octane tune on E85? 40-50 cents less per gallon, it might almost make sense to run E85 all the time.

 

E85 is not 40 to 50 cents a gallon cheaper than 87 octane gas everywhere - it's only about 25 cents cheaper here. This will change your numbers considerably.

 

But it is 40-50 cheaper than 93 octane. I'll be the first to say that on my Mustang it's a Penny Smart / Dollar Dumb modification.

I like it because it supports America and weens us off forign oil. Imagine where we would be today have the government pushed this technolgies since the 70's? We'd be just like Brazil.

And for the nay sayers that claim it take more energy than to make than what you get out of, consider this..

The USDA concludes that ethanol production yields 34% more energy than is used in growing and harvesting grain and distilling it into ethanol

In addition to providing a 34% positive energy gain, ethanol production utilizes mainly domestically available energy, such as coal and natural gas. Therefore for every 1 Btu of liquid fuel used to produce ethanol, there is a 6.34 Btu output.