Understanding Flex Fuel Engines

You may have seen the little badge on a vehicle that says it’s has flex-fuel capabilities, or maybe you even own one. But how does this differ from a regular engine?

Ray Bohacz is Successful Farming’s engineman. He says a flex-fuel engine allows the ability to run on any ratio of gasoline combined with ethanol from E-zero up to E-85. You could even mix them because the engine will adjust on the fly.

"If it’s a flex-fuel vehicle, you could do anything you like. You could have a half tank of E-85 and then fill it up with E-0, E-10, or any blend in between. The system integrates a sensor that tells the control computer for the engine exactly what blend is in there. So, yes, you don’t have to worry about it," says Bohacz. "You could make a home brew, you could fill it up with E-85 and the next day E-20, and it’s going to go down the road happy as a lark."

There are two different systems that engine manufacturers use to identify the amount of ethanol in the gasoline. One is a sensor in the fuel system that electronically reads the amount of ethanol, and the other measures the oxygen content in the exhaust.

Bohacz says flex-fuel engines offer a lot of benefits.

"It allows the consumer to be able to use an American-based product, which is ethanol and also allows the engine to run cleaner, and it also allows the engine to be introduced with a higher-octane fuel at a lower cost for the consumer," he says. "So, ethanol is a win-win-win situation in the ethanol blends."

Ethanol has a lower energy density than gasoline, but the fuel injectors allow for higher fuel flow rates so there won’t be a drastic reduction in overall power.