Running a mixed gas combo

[Gmoney1147]

Curious if you can mix 91 and maybe a gallon or 2 of e85 if it will produce more power. Anyone try it?


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[Denio24]

No, it will run lean, so less power. The ecu will figure this out and kick back timing. Im sure there is a better explanation but this is the general idea.

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[Gmoney1147]

No, it will run lean, so less power. The ecu will figure this out and kick back timing. Im sure there is a better explanation but this is the general idea.

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Really? I saw some guy run it with the Jhm tune


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[derrek]

Ive ran as high as a e55 mix on a 91 tune. the ecu can adapt to fuel quality and add timing for better fuel. You're going to want to watch lambda and fuel trims as the car adjust to the mix. I wouldn't do this if you dont have a lambda or afr gauge to keep an eye on things.

[Denio24]

Ive ran as high as a e55 mix on a 91 tune. the ecu can adapt to fuel quality and add timing for better fuel. You're going to want to watch lambda and fuel trims as the car adjust to the mix. I wouldn't do this if you dont have a lambda or afr gauge to keep an eye on things.

When i ran about 3 gallons e85 to 12 93 oct, the trim ran lean and i noticed reduced power.

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[derrek]

When i ran about 3 gallons e85 to 12 93 oct, the trim ran lean and i noticed reduced power.

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Its a lot easier to work in ethanol % then 2 gallons of this and 3 gallons of that. How long did you run that mix, what were your fuel trims, what was the lambda?

[Denio24]

Ill have to test again, all i know is that it ran lean.

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[derrek]

Ill have to test again, all i know is that it ran lean.

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My car would normally run a little lean at first as it adjusted nothing crazy though.

[Denio24]

The amount of ethanol i added last time was about 20% by volume of gas tank mixed w/ 93 octane. I understand that the octane goes up running more ethanol, however i just dont see how the engine will just add timing. My reasoning, "if its tuned for 93 then put in 93". Also, afr would be lower since ethanol is added.

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[derrek]

The amount of ethanol i added last time was about 20% by volume of gas tank mixed w/ 93 octane. I understand that the octane goes up running more ethanol, however i just dont see how the engine will just add timing. My reasoning, "if its tuned for 93 then put in 93". Also, afr would be lower since ethanol is added.

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. the ecu can add up to 25% more fuel so if you're running your e85 mix it will add the extra fuel to keep the lambda value it wants and it can add more timing. ethanol and gasoline have different stoich values but its always the same with lambda. I'm not very good at explaining but this chart will help.

[Denio24]

Ahh didnt know the ecu could adjust that much! So stoich will always try to be around 1 but afr will probably be a bit lower because of the mix? Wont the ecu be trying to stay at a 14.7 afr for gasoline at all times, even if you put the ethanol mix in? Or will it say hey well you need more fuel and adjust it to a lower afr etc and make that particular afr stoich 1.0

To me it makes sense that the ecu map is what it is, tuned for 91 or 93 octane or whatever, so even if you mix e85 all youre going to be doing is just placing more stress on the fuel system, thus possibly running lean.

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[derrek]

Ahh didnt know the ecu could adjust that much! So stoich will always try to be around 1 but afr will probably be a bit lower because of the mix? Wont the ecu be trying to stay at a 14.7 afr for gasoline at all times, even if you put the ethanol mix in? Or will it say hey well you need more fuel and adjust it to a lower afr etc and make that particular afr stoich 1.0

To me it makes sense that the ecu map is what it is, tuned for 91 or 93 octane or whatever, so even if you mix e85 all youre going to be doing is just placing more stress on the fuel system, thus possibly running lean.

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so stoich is everthing in green on that chart. Stoich is the ratio when all the air and fuel get burned in the cylinder. If you're using AFR stoich changes with the fuel being used but if you use Lambda its always the same regardless of the fuel.

The ECU's in our cars are crazy smart the adjust just about everything to an extent. If we had say a EVO then the ECU is how youre thinking ours is does what its programed every time all the time even if something isn't right.

[Okedokey]

Very interested in this as I am planning on a K04, S4 injector, RS4 module, S3 PRV and sensor and I am going for E85 50%. What do you guys think? KO3 Stage 2+ tune at this stage.

[derrek]

Very interested in this as I am planning on a K04, S4 injector, RS4 module, S3 PRV and sensor and I am going for E85 50%. What do you guys think? KO3 Stage 2+ tune at this stage.

That's a similar setup to what I ran, ended getting a custom tune for 100% e85.

[vce1232000]

There is no E85 gas stations in NJ

[Okedokey]

That's a similar setup to what I ran, ended getting a custom tune for 100% e85.

How'd you go prior to tune?

[danbfree]

I'm no expert but the bottom-line is either run 0% ethanol or 85% and tune for it, nothing in between and this goes on any car... While travelling on vacation right now I put ethanol free 92 octane in my stock car today and the turbo hit noticeably harder, EVEN at high altitude! Ethanol free is where it's at unless you know the source of your far less quality controlled e85 and also tune accordingly.

[derrek]

I'm no expert but the bottom-line is either run 0% ethanol or 85% and tune for it, nothing in between and this goes on any car... While travelling on vacation right now I put ethanol free 92 octane in my stock car today and the turbo hit noticeably harder, EVEN at high altitude! Ethanol free is where it's at unless you know the source of your far less quality controlled e85 and also tune accordingly.

Fuel is fuel you can run e98 or e30 as long as your car is happy. Most pump gas has 10% ethanol anyway.


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[reno808]

The computer has to be tuned for e85 or else it wont run right. You wont get the gains your expecting if its not tuned for e85. Usually when you run e85 you have to run more pressure (richer) than normal when compared to 93 inorder to get more power, but it works very well as it does a good job in keeping knock a bay. I also noticed on the older cars you need to change the rubber lines as well, due to e85 eating them up.

[derrek]

The computer has to be tuned for e85 or else it wont run right. You wont get the gains your expecting if its not tuned for e85. Usually when you run e85 you have to run more pressure (richer) than normal when compared to 93 inorder to get more power, but it works very well as it does a good job in keeping knock a bay. I also noticed on the older cars you need to change the rubber lines as well, due to e85 eating them up.

Like I said earlier the ecu can adjust to an extent and you will see a little without a retune if you run a light mix but if you go and put 100% e85 in your car on a 91/93 tune it's going to run like crap. Yes getting a tune for the specific fuel you're trying to run is the ideal situation but doesn't mean you can't add a little ethanol here and there.


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[typeslone]

There is no E85 gas stations in NJ

I run E85 in my vw drag car. We hae a few options for E85 in the greater north jersey area. Powergas in East Orange has E85 as well as the gulf station next to the Newark airport. Powergas is literally 5 minutes off of rt280. That is my normal go to spot since its only 20-25 mins from me. You can also get E85 on main street in Spring Valley, NY at the Sunoco station there, its a little cheaper than the two NJ stations. The sunoco station on the NY thruway northbound side has it as well as the Sloatsburg area rest stop. There is also a spot for E85 just over the tappan zee bridge, it might be in Irvington, NY or the town next to it, I can't remember at the moment. There used to be a spot by Tuxedo Park, NY also, I'm not sure if they still have it though.

Its been about 2 months since I have stocked up on E85. I will say the last two batches I got ended up testing out to only be E75 or so. One batch was from East Orange and the other was from the Sunoco in Spring Valley. Those little ethanol testers aren't the most precise devices so I very well could have tested them wrong. It only takes 1 or 2 too many drops of water or fuel to mess the reading up haha.

[konarider94]

Ethanol has a leaning effect due to the extra oxygen in the fuel. I'm sure it can compensate for e10-15 but I'm not sure its allowed to adjust enough for e85. They real trick with ethanol blends is to know how much you are putting in so you can tune for it accordingly. Your gains come at different lambda values based on different blends, and from the ability to run more aggressive timing/boost levels.

These cars already struggle to get enough fuel when they are modded that flowing an extra 30% will not be an easy task. To do this the best way you should have a fuel sensor from a flex fuel vehicle. Like typeslone eluded to you never truly know what you are getting with pump gas.

Has anyone incorporated a flex fuel sensor into these cars?
http://www.megamanual.com/flexfuel.htm

[danbfree]

Fuel is fuel you can run e98 or e30 as long as your car is happy. Most pump gas has 10% ethanol anyway.

Yes, it will run but the point is NO ethanol is best for power unless you are specifically tuned for it... just putting in 0% vs. 10% ethanol really made a difference to the point I'm going to go out of my way to fill up with it whenever possible.

[RakkCity]

Yes, it will run but the point is NO ethanol is best for power unless you are specifically tuned for it... just putting in 0% vs. 10% ethanol really made a difference to the point I'm going to go out of my way to fill up with it whenever possible.

How can I tell which gas stations near me are 0% vs 10%? pure-gas.org only lists two places nearby in socal, one a performance shop and the other a garage/repair shop it sounds like.

Edit: Wait, I'm dumb. Ethanol free is 100 Octane, isn't it..

[danbfree]

How can I tell which gas stations near me are 0% vs 10%? pure-gas.org only lists two places nearby in socal, one a performance shop and the other a garage/repair shop it sounds like.

Edit: Wait, I'm dumb. Ethanol free is 100 Octane, isn't it..

Ya, I was traveling in more rural central Oregon, ethanol free is definitely harder to find but it's more available up here than down in SoCal it looks like... but it's also not 100 octane, I found it in the normal 92 octane for Oregon.

[aluthman]

There is no E85 gas stations in NJ

Maybe there is, but because you can't pump your own gas, you've never seen it.

[seal66]

I love reading these threads ha ha.

Coming from hauling fuel you are going to a slightly %swing on your fuel values ie...85,87,91,92,93, e85. US fueling standards are a min of 10% ethanol in any fuel blend unless you are lucky enough to have a fuel station that has straight gas with 0 ethanol. Which is awesome btw.

E85 can have a massive swing in ethanol content. You can have a swing from 50% up to 85% at any fuel station. Some station regulate it more to keep it closer to true 85% content though.

In terms of tuning, a fuel sniffer is the easiest way cause it makes adjustments on the fly to what it senses for ethanol %.

It helps to have the car tuned for additional ethanol content over a regular 91/93 tune.

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