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Table of Contents

Why should I switch to E85?

Why Should I Run E85?:

E85 is sort of an interesting case in the fuel world. It actually performs 27 percent less work than traditional gasoline and has an ideal mixing rate of 9.8:1 which means you need much more fuel when compared to gasoline's 14.7:1. E85 is not an entirely petroleum based fuel, in fact it's name comes from the fact that it's 85% ethanol (this amount can vay vary from 65-90%) and 15% gasoline.  Since this fuel is so different from gasoline, you can run into issues when using it with parts not designed for it, this happens because ethanol is hygroscopic.  Which means that much like honey, ethanol has a propensity to attract water (even out of the air) and that water can have a detrimental affect on steel fuel lines (mandating a change to anodized aluminum ones) injectors and fuel pumps. In older cars with steel gas tanks (most cars haven't had them since the 80's) E85 will clean the tank, at the downside of pushing silt into the fuel system. E85 will destroy older rubber hoses and gaskets but if they were made in the last 20 years or so the rubber is resistant and it won't make a big impact.

So Why would I use it?

The biggest reason is Octane. Octane is a fuel's resistance to detonation or self-ignition (also called knock) which essentially means it's resistance to lighting itself on fire when heated or put under pressure.  On vehicles which run high compression or are turbocharged, a high octane rating is required to prevent the fuel from igniting early. Despite needing more fuel going into the engine, it's increased octane rating (Typically 105) means you can run more aggressive timing and boost levels on an engine while being much happier than the car originally was on pump gas. In addition Ethanol is much better than regular gasoline is at absorbing heat from the air, which lowers temperatures going into the engine and that cooler denser air charge brings a few more horsepower to the table as well. As the fuel is injected into the engine by the injector, it begins to atomize and evaporate.  So if you're looking for a cheaper alternative to race gas, or trying to get another power upgrade on an already modified car.

With our flex fuel kit there are additional benefits beyond just being able to use e85 in your car.  Our ethanol sensor actively monitors the content of ethanol in the fuel, and automatically modulates your vehicle between your gasoline tune and your e85 tune.  This means that not only can you fill up with whatever is at hand without having to worry about your ratios, but once you've gotten your initial tunes dial in, you won't need to drain the tank when you want to switch from one to the other.  Just fill up with ethanol on your way out to the track, cruise around with the higher power level of your e85 tune, and on your way home you can fill up with gasoline and enjoy the higher mileage abilities of that fuel.  This means that unlike traditional e85 conversions, you aren't limited by the location of the next station that actually sells e85.



Full Links:

Flex Fuel Article

Link to Staged Flex Fuel Packages (Currently Only Available for 2008-14 WRX and WRX STI)


  • E85
    • A Blend of fuel combining 65%-90% ethanol (Typically made from corn or sugarcane) and 15% gasoline.
  • Flex Fuel
    • The ability of a vehicle's ECU to compensate for a change in ethanol content without prompt.