E85

E85 is an abbreviation for an ethanol fuel blend of 85% denatured ethanol fuel and 15% gasoline or other hydrocarbon by volume.

In the United States the exact ratio of fuel ethanol to hydrocarbon may vary according to ASTM 5798 that specifies the allowable fuel ethanol content in E85 as ranging from 51% to 83%. This is due to the lower heating value of neat ethanol making it difficult to crank engines in relatively cold climates without pre-heating air intake, faster cranking, or mixing varying fractions of gasoline according to climate. Cold cranking in cold climates is the primary reason ethanol fuel is blended with any gasoline fraction.

In Brazil ethanol fuel is neat at the pumps, hence flexible-fuel vehicles (FFV) including trucks, tractors, motorbikes and mopeds run on E100. The 85% fraction is commonly sold at pumps worldwide (outside the US), and when specifically supplied or sold as E85 is always 85% ethanol (at pumps or in barrel). Having a guaranteed ethanol fraction obviates the need for a vehicle system to calculate best engine tune according to maximise performance and economy.

In countries like Australia where E85 is always 85% ethanol (and pump fuel with varying fractions is called Flex fuel), performance motoring enthusiasts and motor racing clubs / championships use E85 extensively (without the need for any FFV certification). Use of alcohol (ethanol and methanol) in motor racing history parallels invention of the automobile, favoured due to inherent combustion characteristics such as high thermal efficiency, raised torque, and with some advanced engines better specific fuel consumption. In the United States, government subsidies of ethanol in general and E85 in particular have encouraged a growing infrastructure for the retail sale of E85, especially in corn growing states in the Midwest.

E85 reduces exhaust emissions, there is a greater potential for localized production of ethanol in agricultural areas and utilization of waste materials. Also, a diversification of fuel sources reduces dependence on any one particular type of fuel and may increase stability of supply.

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