There are some on this forum that still don't get it. :R I will try to explain this one more time:
Ethanol is an oxygenating agent. That is why they put it in gasoline. It is put in there to bring up the O2 level to help with smog at the engine level. It also has 2 more side benefits:
#1. It brings up the octane of the fuel. Ethanol has a RON of around 113 octane! So it's a cheap way to bringing up the octane of gasoline.
#2. Anytime a fuel has more "liquid O2" in it; it will make
MORE POWER, not less!!! One more time; E anything will make MORE POWER than straight gasoline.
Engine making MORE power on fuel with O2 in it. Pretty cool hu?
See how that works now? Simple hu? Understand?
Now, all that being said, there are many bad things about E fuels. One of the biggest is mileage. Anytime you brings the BTU's of a fuel down your mileage will also go down. Ethanol has less BTU's so your mileage WILL be less.
I heard people on this forum say that they get 10, 15 or even 20%+ less mileage from E10. If it is truly E10, this is impossible. Even if your E10 gasoline has 0 BTU's, (impossible by the way) the MOST loss you will get is 10%. The loss you will see in the field with E10 is around 3 to 4% which is right where the math says it should be.
Now, I have to go out and prep my car to go racing this weekend. Anybody have any guess if I'm going to burn pure gasoline or am I burn E10 in it? :B