Jocie Iszler letter: Benefits of E85 more than mileage

[RC]

There are many upsides to E85: less dependence on foreign oil, reduced trade deficit, growing a market for corn, cleaner air, an alternative to fossil fuel that is renewable, plus more power. A gallon of pure ethanol has 134 octane. A gallon of E85 is 105 octane as compared to 87 regular, 89 super, or 92 premium. The headline power may suffer? was incorrect.
The one downside that most agree on is the decreased mileage. But "decrease" is a relative term. There is great deal of variation in the degree of decrease experienced by drivers of flex-fuel vehicles. Some flex-fuel vehicle owners have found that working with the dealer's mechanic on calibrating the engine with software updates or checking the thermostat has improved fuel economy. There are many factors that influence fuel economy.

http://www.in-forum.com/articles/index.cfm?id=108603§ion=Opinion


So you get more power, but a decrease in gas mileage? That doesn't compute.

Octane is a measure of how fast something burns. With the writer's thinking(?) then water, which does not burn under normal conditions, would have almost infinite octane, therefore infinite power. If he is wrong about this, what else is he wrong about? Other than the fact it takes more energy from oil to produce a given unit of ethanol than you get back from the finished product.

[acmejack]

1. I thought it was a measure of compressibility?

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites.

http://auto.howstuffworks.com/question90.htm

[RC]

2. WHAT IS OCTANE RATING?

WHAT IS OCTANE RATING?

Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine design to ensure complete burning of the gasoline by the engine for maximum fuel economy and clean emissions.

http://theserviceadvisor.com/octane.htm