Why is everyone running E85?
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Do I have to empty out my gas tank to fill it up with e85?
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That depends on your tune. If you're running a true flex fuel setup then you can run any mixture of gasoline/ethanol you want. If you're running multiple tunes then you will want to empty your tank as much as possible before filling up and switching maps. You could talk to your tuner about how much you will really need to empty the tank before switching fuel types.
Oh okay I just got a Wrx 17 and I'm all new to this stuff ..
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I wouldn't say you have to have substantial modifications.. depending on the year model you could run it with nothing more than injectors, fuel pump, and a tune. With the 15+ WRX you could run it with nothing more than a tune if you wanted (although the HPFP in the DI engine doesn't hold up well without a decent amount of the lubricants that are found in gasoline, so there have been some pump failures.. a lot of people opt to run a weaker blend for this reason).
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To your average person, that isn't a simple undertaking. You are also forgetting the flex fuel sensor you'll want to have because the quality of e85 in some places is very suspect.
Physically doing the work no, it isn't painfully difficult, however to someone starting to modify their vehicle it's a big first step as there is a lot to move and you will have to have a tuner ready to dyno your car.
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Physically doing the work no, it isn't painfully difficult, however to someone starting to modify their vehicle it's a big first step as there is a lot to move and you will have to have a tuner ready to dyno your car.
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A lot of people have successfully ran e85 for years without the use of flex fuel sensors. A typical e85 tune will be fine with anywhere between 70% and 99% ethanol due to its high knock resistance. Also consider the fact that as the ethanol content decreases, the tune will become richer (assuming you're not doing flex fuel), which creates an added safety margin. That said, without an ethanol content analyzer it's good practice to test the fuel before filling your tank. Test kits can be had rather cheaply (but it is a hassle).
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It's definitely a concern to take into account. A fuel pump failure could take the engine out along with it.. but at the same time I haven't seen any reported failures from people running <60%.
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lol.. your sig matches this post perfectly
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Yeah the 40-50% seems to be the tipping point for it.
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Just curious after reading this thread. We have multiple stations with E85 locally, and I'm wondering if they list the ethanol percentage of the E85 on the pump? I've never really had a reason to read the fine print on E85 pumps. It sounds like 50%-60% is where you want to be if running the WRX on E85, and you probably end up mixing it with 93 to get the correct %?
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Depending on the modification level of the modern FA20 WRX, it seems that the fuel system does become an issue when running full 85% ethanol. From what I've read, that's the reason most tuners prefer to use E30 to E60 to power the DI cars.
Really, the correct answer to your question is that you should be using an ECA (ethanol content analyzer). There's really no excuse not to run an ECA particularly since Cobb now supports Flex-fuel with ECA input. Even the same pump may vary the ethanol content as much as 15-20% over the seasons which is enough to change your fuel accuracy by 5-10%.
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