Photo Courtesy of Wisconsin Corn Growers Association

Photo Courtesy of Wisconsin Corn Growers Association

Though E85 has been on the market now for some time, there are still some misconceptions that we often hear in our travels. As a follow up to our more comprehensive story on ethanol and performance engines, we decided to call Duane Minazzi, Senior Chemist at VP Racing Fuels, who helped extract a few more facts you may not have know about this popular fuel choice.

  1. It’s not just the ethanol percentage that varies out of pump E85

“In pump E85, they are concerned with vapor lock, and Winter gas has a lot of vapors. If you were to use winter gas in a warm environment, the car would be hard to restart when hot. Plus, you’d have to worry about boiling the fuel in the tank. With Summer fuel in a cold environment, you might have poor throttle response and a hard time starting the engine.”

  1. It’s not just the ethanol percentage that affects your tuning

“With race fuel like our C85, it is going to have the same density (gravity), oxygen content, and vapor pressure every time. This helps limit the variables for tuning the engine. It’s essentially a mass flow equation; if there is no oxygen content in the fuel, then you will need more air. If there is oxygen content in the fuel, then you will need more fuel and less air. As the fuel’s gravity increases, you are adding a higher mass of fuel per time. Without tuning changes, you will run richer with a higher gravity fuel and leaner with a lower gravity fuel.”

  1. Your typical ethanol tester might not work with race E85

“The other 15-49-percent of E85 pump fuel is hydrocarbons. Race fuel may include the use of an oxygenate or other elements that can easily mix with water in the test tube instead of separating.”

  1. Ethanol is chemically denatured

“Fuel ethanol comes denatured so that you can’t drink it. The denaturant typically makes up around 4-percent, so that typically comes out to be 82-percent pure ethanol content per tank if the fuel has 85-percent denatured ethanol.”