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Why is everyone running E85?

24K views 34 replies 10 participants last post by  lawadm1 
#1 ·
I heard it makes your car faster idk .. what else does it do


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#9 ·
The 17 WRX can't at all. The high pressure fuel pump is not e85 comparable and will melt down. There is not an aftermarket unit, and from what I've been reading there likely won't be.

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#11 ·
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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#13 ·
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.

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).
 
#15 ·
There are some aftermarket options for a hpfp, though COBB still does not recommend running a true E85, not sure if they would tune for it here either.(Surgeline)
 
#19 ·
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 %?
 
#20 ·
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%.
 
#22 ·
So honestly...Is the amount of power you gain from running the E85 mod worth the effort and worry? Like making sure the fuel is the correct mixture? And what if you go on vacation to a place that doesn't sell it? Do you or can you you even put back your 93 octane map? I apologize, I haven't done much research on it yet, but I see the popularity of it going on lately.

And my closest tuner would most likely be in the Chicago area a couple of hours away. Unless there's a good e-tuner out there. I've heard Ron mentioned at Phatboti.i
 
#23 ·
The gains are significant, loads more torque, and the turbo spools earlier. If you run flex fuel you don't have to worry about the mixture at all. You can fill the tank with anything between straight 93 octane, to e99 and it will adjust the tune accordingly on its own. Ethanol also doesn't burn as hot as gasoline, and it is VERY knock resistant.. so in a lot of ways it's actually better for the engine.



I would not e-tune for e85.. since e85 is so knock resistant the car needs to be on a dyno to see where it has surpassed TDC and the timing needs to be dialed back.
 
#24 ·
E85 can be a little to alot cheaper per gallon than Super 93 (especially if you live in the corn belt). Though E85 has higher octane (knock resistance), which is great for making horsepower numbers - technically it's less power per gallon of gas, so you'll get less miles per tank / fuel mileage. While the dollars spent might work out the same (save money per gallon but end up filling tank / going to station more often).

If it's so good, why isn't everyone running it then?

1) Availability. The further away you are from a corn producers / refinery, the more it costs. It might still be
cheaper than gas, but maybe not THAT much cheaper, especially if gas is still cheap where you are.
2) Not everyone is willing to sacrifice convenience for max performance
3) Given the scope of the mod, it definitely falls into the category of mods that break your warrarnty and people may not want trash their warranty quite yet if their cars still have one.
4) As others have stated earlier, most older cars need more parts to run E85, since that much alcohol will wear out the old rubber hoses and parts as well as computer tuning to be able to use all that extra octane.

FWIW
 
#26 ·
I basically live in the middle of corn fields in central IL, and right now I see E85 for $1.89/gal. And BP 93 Octane is about $2.80/gal.

I have a 2016 WRX, and from watching some of the YouTube videos, it doesn't seem like a difficult mod at all. And with the 2015+ WRX, do you even have to worry about timing? I thought I read somewhere, the timing isn't an issue with these motors, but I could be confusing it with something else.
 
#30 ·
What are the gains of E85 tune over being at Stage 2 tune, with Jpipe and an intake?
I'm just looking for a guesstimate, and I realize there may be more supporting mods needed for E85.
 
#32 · (Edited)
Well slap me and call me Shirley. That's pretty impressive.

The MAPerformance page has a much different graph for stage 2:
https://www.maperformance.com/colle...ge-2-ots-tune-2015-subaru-wrx-wrx-4g-ots-stg2


I read something last night about the 2015+ WRX rear differential not being able to handle too much torque. Does the torque in the E85 graph fall within the safe range?

Quotes:
"With all racing comes the risk of broken parts and as we have turned up the power we’ve already started finding weak links. The first serious issue we’ve run into is a result of the hard launches. Both times we’ve been to the dragstrip and launched the car with ethanol in the tank we came home with a broken rear end. Both times the spider gears in the differential shattered during a launch causing catastrophic differential failure."

"The car is just too heavy with too much torque for the tiny Subaru R160 rear differential. The STI models have an upgraded R180 differential and beefier axles to help with this issue but unfortunately the WRX was not so lucky. "
 
#33 ·
Well slap me and call me Shirley. That's pretty impressive.

I read something last night about the 2015+ WRX rear differential not being able to handle too much torque. Does the torque in the E85 graph fall within the safe range?

Quotes:
"With all racing comes the risk of broken parts and as we have turned up the power we’ve already started finding weak links. The first serious issue we’ve run into is a result of the hard launches. Both times we’ve been to the dragstrip and launched the car with ethanol in the tank we came home with a broken rear end. Both times the spider gears in the differential shattered during a launch causing catastrophic differential failure."

"The car is just too heavy with too much torque for the tiny Subaru R160 rear differential. The STI models have an upgraded R180 differential and beefier axles to help with this issue but unfortunately the WRX was not so lucky. "
I'd be more concerned about the OEM transmission in the WRX versus the R160. When considering the driveline, the weakest point in the WRX has always been the transmission.

Keep the torque under roughly 380 lb-ft (on a dyno that reads OEM 260 lb-ft) and be smart about your driving. Hard launches with all that torque would certainly put greater strain on the gearbox.
 
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