I know this is an old thread but you guys need to give your head a shake here. The only advantage of E85 is easier on the environment. You do not get better fuel economy and you definitely do not get more power than premium.
Do a little research and you will see that ounce per ounce 91 has more potential BTU (actually WAY more) than E85. E85 has an octane rating of 87, where as 91 has...you guessed it...91. This means less detonation, which means less retardation, more power. That's not taking into account the BTU thing....
You are incorrect. First, pure 100% ethanol is 105 to 113 Octane. Nascar even claims 113 Octane using E100 at the track. The variance is all due to moisture content. Alcohol is hygroscopic; it soaks up moisture. If you have a FFV you can actually go to a liquor store and buy pure spirits that is 92 Proof and put it in your tank. They mark it as 92 Proof when it is actually 100 Proof in the sealed bottle. However, they have to mark it as 92 because once you open it the alcohol begins to take on moisture. Within days it will take on enough moisture to settle in at 92 Proof. It's a good idea to buy some of this, place it in a yellow gas can (1 or 2 gallon size) and keep it in your trunk for emergencies. You should not do this with E85 since up to 30% of it will be gasoline.
Your E85 is blended 87 Octane gas and E100 which is pure Ethanol. Her is the breakdown:
E100 at 85% (113 octane pure ethanol)
Regular at 15% (87 octane)
Final Summer Blend: 109.1 octane
E100 at 70% (113 octane pure ethanol)
Regular at 30% (87 octane)
Final Winter Blend: 105.2 octane
Other benefits besides the environment are:
- Cooler running engine
- Less carbon build-up; much less. In fact the ethanol will keep every part of the combustion chamber spotless. No need for STP gas treatment.
- Less expensive as to run as long as your above your break-even. For example, my 2001 CLK320, running a FuelFlex converter box, loses about 10-15% in mileage per gallon of E85; 15% local streets and 10% highway. I pay $2.70 now for E85 and 93 Octane is $3.35. The difference is $.25 per gallon based on the loss in fuel consumption. That's $.25 saved per gallon. When I was paying $2.15 this summer and 93 Octane was $2.99 per gallon I saved $.52 per gallon. That's a net savings of $9.36 per tank. Again, the savings are longer engine life, more HP at the wheels and yes, a cleaner car!