Please educate me about E85

[GID]

i own a c7.5 for what that's worth.

Manual says 91 or above. I've been using 93 because that's what's available to me but i keep reading about people running a cheaper e85 and supposedly it's better for performance. Do you need to be runnning a specific tune map to use this gas and gain performance as well as not harm your motor?

Does running e85 add any long term worries to these motors?

I just don't get why everyone isn't running e85 if it's better for performance and it's cheaper.

What am i missing here?

BTW, i purchased an EPL stage 1 and getting ready to flash for the first time in the next few days (93 map).

This is a dangerous road I'm heading down for my wallets sake.

Thanks everyone, for helping this new Audi owner.

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[Hofahome]

You can't run pure e85 or you will for sure run lean. You can run about 2-3 gal of e85 with either 91 or 93, which acts to bump up the octane rating a few points. E85 can make more power and burns cleaner, but requires much more fuel flow, so you have to upgrade the fuel system to run full e85 (unless of course the car is made to run on it - which ours aren't).

[GID]

Thanks.

So if i switch from a 93 to e85 tune, will it then be able to run straight e85?

Mixed or straight, does it negativity affect the life of the motor in any way?

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[G_Wagon]

U need to have a flex fuel Audi...

[kpriv]

I'm no expert here, but have done a decent amount of google research on this subject over the past couple months. The quick and dirty is that e85 is higher octane (true e85 - 85% ethanol - is 105 octane). But due to the properties of ethanol you need a lot more to have an appropriate air/fuel ratio as hofahome pointed out. So you cant run pure e85 without modifying your fuel delivery system to significantly increase the volume moving into your combustion chamber. This is why you should log lambda when playing around with blends to make sure your system isn't running too lean and pulling timing.

The easiest way to think about it is that in most states, "regular" gas is e10 (10% ethanol). You can do the weighted average math to calculate different blends of e10 of various octanes (91, 93, etc) and e85 @ 105 octane to figure out how to increase your octane a bit. One word of caution with this though -- e85 at the pump can actually vary from ~e55 to e85. So if you're blending regularly and running a higher map, make sure you know what e-content you're adding to your fuel system.

I'm doing this and blending e85 with pump gas because in california the highest octane rating we have is 91. So I blend with e85 to get my octane to 93 and run the 93 map. Personally, it wouldn't be worth it to mess with if I had 93 at the pump (not sure whether its even worth it to bump up from 91, but its a fun experiment and we'll see how long it lasts).

[GID]

Thanks for the breakdown, very informative.

So what fuel or blend of fuel are the folks running the e85 tune using?

To run the e85 tune, are people simply changing the fuel or are there other modifications to the motor done to support the use of the tune and e85 fuel?

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[Hofahome]

I assume you have a 3.0t, and EPL does offer an e85-specific tune. Here is the HPFP insert that you would need to install:

http://www.autotech.com/mm5/merchant...de=10-127-101K

Word of caution though (I ran e85 on my b8.5 S4 with EPL tune): I found it to be more of a PITA than anything. I did feel a difference in power, however the fuel economy takes a hit by at least 3-4mpg and you have to always find e85 stations. I caused some amount of range anxiety in the end and I even work right by an e85 station.

[GID]

I assume you have a 3.0t, and EPL does offer an e85-specific tune. Here is the HPFP insert that you would need to install:

http://www.autotech.com/mm5/merchant...de=10-127-101K

Word of caution though (I ran e85 on my b8.5 S4 with EPL tune): I found it to be more of a PITA than anything. I did feel a difference in power, however the fuel economy takes a hit by at least 3-4mpg and you have to always find e85 stations. I caused some amount of range anxiety in the end and I even work right by an e85 station.

This. Exactly what i was wondering. Thank you.

So are there any known detrimental impacts to the motor with extended use?

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[ntsantos]

I've been running the EPL e85 tune paired with the Autotech HPFP for almost 2 years now with no issues. I can run full e85 or as low as e50 without any significant power loss at e50. If you decide to play with e85, you should get an ethanol sensor to know your exact e%. Gas mileage does suffer a lot, but with EPL, I can always flash to the 91oct file from anywhere if needed.

[mariokart]

I’m stage 1 RS7 and California has weak 91 octane, so I mix 3 gallons of E85 (80% Ethanol is my area) and fill the rest of the tank with 91. I’m guessing it’s gets me around 94 octane. The car does run stronger. I used all E85 in my GTR. I was able to run 100whp more over 91, but it used 35% more fuel. I had to upgrade to 1300lb injectors, twin FP and a flex fuel module. It would awesome if the RS7 were capable using all E85.


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[pez81]

Arin are there any plans to develop an E85 tune for the 4.0T platform?

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[kpriv]

...I mix 3 gallons of E85 (80% Ethanol is my area) and fill the rest of the tank with 91.

You buy your corn gas from the silvas station in ventura? I live in westlake and pop up there from time to time with three 2.5 gal gas cans. That way I can fuel up at a local shell and add 2.5 gal of e85 at the same time so I can run the 93 file as well. Haven't been doing this for very long, but I've tested the e85 from that station for ethanol content and it looked pretty good.

[mariokart]

You buy your corn gas from the silvas station in ventura? I live in westlake and pop up there from time to time with three 2.5 gal gas cans. That way I can fuel up at a local shell and add 2.5 gal of e85 at the same time so I can run the 93 file as well. Haven't been doing this for very long, but I've tested the e85 from that station for ethanol content and it looked pretty good.

That’s the station I go to, I live in Agoura Hills now but I’m in Ventura a few times a week. My GTR had a gauge to measure E85 purity and it was always 80% even in the winter. Arizona E85 was around 58% even in summer. Anything g over 70% gave my GTR full power


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[All Flash]

I was under the impression that pure gas(no ethanol at all) V power shell 91 or chevron 94 were the best gas to use......what am i missing?

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[Packy]

I've seen research on the fuel mixes and if there is anything between 15 and 85% ethanol then it can phase separate out. Not good to mix fuels.

[mrb5_supra_wrx]

I was under the impression that pure gas(no ethanol at all) V power shell 91 or chevron 94 were the best gas to use......what am i missing?
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Most stations about 90% of them add 10% ethanol to their fuels. Some still believe its better to run without so they market to those people that are stupid enough believe the anti ethanol hype and realize ethanol is actual helping their cars.

I've seen research on the fuel mixes and if there is anything between 15 and 85% ethanol then it can phase separate out. Not good to mix fuels.

This is not true.. well not necessary . If the two fuels sit for an extended period of time like months or years under harsher conditions like high heat or cold they could possibly separate but ive never seen them do this within my usage. Alot of people even use the heat to make the e85 stronger when adding it to their pump gas mixture like leaving the e85 out in the sun before mixing tho so it cant get any worse than that

[All Flash]

Lol ...pretty sure you just called me, and most who don't know alot about gas mixes stupid MRB 5..... What is ethanol helping my car with? Cleaning? Performance? Since you are so knowledgeable MRB 5 maybe you should educate instead of name calling..... jerk! 😜

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[GID]

Is anyone using a ethinol blend without upgrading hpfp or other fuel line hardware upgrades? I'm on EPL stage 1 and been advised it should be okay (about 3 gal per tank) but I'm curious if there will be any long term or imediate adverse effects. Any thoughts?

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[OlyS6]

Is anyone using a ethinol blend without upgrading hpfp or other fuel line hardware upgrades? I'm on EPL stage 1 and been advised it should be okay (about 3 gal per tank) but I'm curious if there will be any long term or imediate adverse effects. Any thoughts?

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A bunch of folks with our cars run a total of about E25 or so. It is very helpful to run an ethanol analyzer, such as theone made by Zeitronix. Depending on your pump gas, generally 2-2.5 gallons of e85 per tank will bring your e content to about 25%. This will typically bring 91-92 octane up to 93 octane. It can help act as detergent somewhat as well. Problems with running too high of an econtent (suposedly more than 30% or so) in our cars can lead to corrosion of the fuel system, since it wasn’t designed for it, and certainly not for straight e85. Another potential issue is that if not handled/ used properly, a high econtent can disassociate into water.


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[GID]

A bunch of folks with our cars run a total of about E25 or so. It is very helpful to run an ethanol analyzer, such as theone made by Zeitronix. Depending on your pump gas, generally 2-2.5 gallons of e85 per tank will bring your e content to about 25%. This will typically bring 91-92 octane up to 93 octane. It can help act as detergent somewhat as well. Problems with running too high of an econtent (suposedly more than 30% or so) in our cars can lead to corrosion of the fuel system, since it wasn’t designed for it, and certainly not for straight e85. Another potential issue is that if not handled/ used properly, a high econtent can disassociate into water.


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Thanks for the explanation. Other than the savings of a few dollars per fillup, are there any other benefits? It seems that I'd only save about 4-5 dollars and with the decreased MPG, it almost seems like a wash. Would you say it helps with performance? The truth is I just want to try it but I don't want to do it if there is negligible gains and introduces other risks.

[OlyS6]

It does in fact increase the octane of your fuel, which is why I run it. Some Western states like CA and WA make it impossible to obtain 93 octane fuel at the pump, and it is detrimental to run a 93 octane tune with only 91 or 92 octane fuel. If you have 93 octane fuel readily available, then likely not worth the hassle. With the gauge, I can see exactly what econtent I'm running- at 23 or 24%, I know I'm running 93 octane fuel (based on my WA92 plus about 2.5gallons of e85), which matches my 93 octane tune, so I'm much less likely to have problems with misfires and timing issues. Thus far, my logging of misfires shows them to be linear and fairly minimal in the background. Some folks believe you are also less prone to develop carbon buildup around your piston-rings over time given the 'detergent' properties of burning a slightly higher econtent, but I have no concrete evidence of this. For me at least, it makes more sense to run at e25 or so to ensure I can most safely run my 93tune, since I don't have 93 octane readily available in WA.

[cbest13]

It does in fact increase the octane of your fuel, which is why I run it. Some Western states like CA and WA make it impossible to obtain 93 octane fuel at the pump, and it is detrimental to run a 93 octane tune with only 91 or 92 octane fuel. If you have 93 octane fuel readily available, then likely not worth the hassle. With the gauge, I can see exactly what econtent I'm running- at 23 or 24%, I know I'm running 93 octane fuel (based on my WA92 plus about 2.5gallons of e85), which matches my 93 octane tune, so I'm much less likely to have problems with misfires and timing issues. Thus far, my logging of misfires shows them to be linear and fairly minimal in the background. Some folks believe you are also less prone to develop carbon buildup around your piston-rings over time given the 'detergent' properties of burning a slightly higher econtent, but I have no concrete evidence of this. For me at least, it makes more sense to run at e25 or so to ensure I can most safely run my 93tune, since I don't have 93 octane readily available in WA.

Sell me your car for book value?? lol.