Also named Flex fuel, E 85 is a type of fuel that blends 51% up to 83% ethanol into gasoline. The use of this type of fuel is common against modded cars, and will normally require generous amount of modifications of the mapping of the ECU to fully utilize the potential of E85 flex fuel.
However, due to the lower heating value of ethanol, it causes engine to be a lot harder to crank in relatively cold weathers without pre-heating of intake air, cranking faster, or mixing fractions of gasoline according to climate. Cold cranking ability is the reason ethanol fuel is blended with gasoline in the first place.
Because of the unique properties that E85 has, FFV(Flexible fuel vehicles) has several design difference from vehicles that are not FFV. First and foremost is the elimination of bare magnesium, aluminium and rubber parts in the fueling system. Fuel injectors systems also have a wider range of pulse width to inject up to 34% more fuel(also means more power) Stainless-steel fuel lines, in some cases lined with plastics, and stainless steel tanks is used. As tuners put lots of hardwork into maximizing engines to take advantage of E85’s higher octane, engine can thus achieve great power advantage. Some car can provide 20% more power when E85 is used. This is due to the better cooling efficiency that E85 has. E-85 has octane rating much more than normal gasoline, makes it perfect to be used in high compression ratio engines, as they are less prone to misfire and cause engine knock. According to the lowa Renewable Fuels Association, E85 can cite an octane rating of just under 105. Texas State Energy Conservation Office cites it at 113 octane rating.
A lot of tuners who drives a non E85 fuel capable car make modifications to accommodate E85, especially when they modded the engine excessively, as the lower heating value, which can lower engine block temperature, lower head temperatures, and the main thing is lowering intake temperature capability of E85 provides a cooler intake charge and when met together with high stability level from its high octane rating had been widely used as power booster in turbocharged vehicles. This modification is widely executed as it not only produces lower emission than standard gasoline, it also resulted amazing power and torque increase of 10-12%. Compared with when the engine uses gasoline as its fuel and is limited to engine knock, power improvement is as much as 40%. Despite all the performance E85 provides it is surprisingly lower priced than gasoline and is in high availability as tuners replaced expensive high end racing fuels which costs more than $10 a gallon.
Despite the fact that a lot of modifications might have to be made if your car is not FFV, modifying your engine to accommodate with E85 is completely worth it and is in a lot of tuner’s to-do list, as it provides so much more performance, and E85 is cheaper than most high octane rated gasolines.