Mixing 91 octane and E85?

**wootwoot** · 01-25-2015 02:23 PM

There was some discussion in another thread about adding a couple gallons of E85 to a tank of 91 octane to increase performance. I used the calculator from http://www.intercepteft.com/calc.html and it looks like 2.5-3 gallons of E85 would raise the octane level to 93 and the ethanol content of a tank would be around 22%. Is it safe to add E85 to 91 octane to boost the octane level to 93?

**_muppet_** · 01-25-2015 02:53 PM

No, don't do that. E85 is higher octane, but requires a richer mixture. You will run lean mixing like that without tuning for it.

**wootwoot** · 01-25-2015 02:59 PM

Originally Posted by _muppet_

No, don't do that. E85 is higher octane, but requires a richer mixture. You will run lean mixing like that without tuning for it.

I forgot to mention that I am running JHM stage 1 so the tune should adapt to the higher octane.

**_muppet_** · 01-25-2015 03:21 PM

Octane is not the issue here, the issue is that e85 requires a richer mixture, and unless the tune was made for this strange blend, then the ecu is only going to inject enough fuel for the proper mixture using gasoline.

**Andrew149** · 01-25-2015 04:59 PM

I wish it was that easy to get to 93 octane

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**vce1232000** · 01-25-2015 06:52 PM

Originally Posted by Andrew149

I wish it was that easy to get to 93 octane

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Must be a west coast thing

. 93 Octane is a normal thing here

**_muppet_** · 01-25-2015 07:22 PM

Yeah, but E85 isn't.

I'd love to be running it in my vrt, but I'm about two hours from the closest station with E85. I think I'm about as far away from E85 as one can be in the state of PA.

**aluthman** · 01-25-2015 08:22 PM

Originally Posted by _muppet_

No, don't do that. E85 is higher octane, but requires a richer mixture. You will run lean mixing like that without tuning for it.

Originally Posted by _muppet_

Octane is not the issue here, the issue is that e85 requires a richer mixture, and unless the tune was made for this strange blend, then the ecu is only going to inject enough fuel for the proper mixture using gasoline.

^This is wrong. The car adds fuel based on the lambda value it is reading from the O2 sensor. 1.00 lambda is stoich no matter what you are burning. It simply measures the excess oxygen present in the exhaust. For older cars that have no O2 sensors or simple narrow band sensors, yes, you would need tuning. The 2.0 is advanced enough to where this wouldn't cause any trouble. I have done it before with 50% of my tank being E85, and the only differences I saw were changes in fuel trims due to the car needing to flow more fuel to put out the same power. This increase in fuel trims is proof that the car can and will add the extra fuel it needs to keep everything happy.

**mec** · 01-25-2015 08:26 PM

Originally Posted by aluthman

^This is wrong. The car adds fuel based on the lambda value it is reading from the O2 sensor. 1.00 lambda is stoich no matter what you are burning. It simply measures the excess oxygen present in the exhaust. For older cars that have no O2 sensors or simple narrow band sensors, yes, you would need tuning. The 2.0 is advanced enough to where this wouldn't cause any trouble. I have done it before with 50% of my tank being E85, and the only differences I saw were changes in fuel trims due to the car needing to flow more fuel to put out the same power. This increase in fuel trims is proof that the car can and will add the extra fuel it needs to keep everything happy.

i heart you adam....I wanted to post this all day...but I was waiting for someone else to chime in and fuckin set the record straight. You give me confidence in this platform. Maybe one day we can ascend past the shitty products like frankenturbo and get on a new level. Like the evo kids. But we would obviously look way cooler going fast because our cars don't look hilarious.

**aluthman** · 01-25-2015 08:31 PM

Originally Posted by mec

i heart you adam....I wanted to post this all day...but I was waiting for someone else to chime in and fuckin set the record straight. You give me confidence in this platform. Maybe one day we can ascend past the shitty products like frankenturbo and get on a new level. Like the evo kids. But we would obviously look way cooler going fast because our cars don't look hilarious.

I got you bro.

**ericpaulyoung** · 01-25-2015 08:52 PM

The limiting factor is maximum fuel delivery. The Motronic will adjust, but its ability to do so is limited. For a stock K03 style setup, it can probably adjust enough. For a K04 or higher, you will start hitting limits in the low pressure delivery system. Which is why Seth has a drilled pump etc. But yes, the Motronic adjusts to Lambda and not AFR, and is a great system. :)

epy

**aluthman** · 01-25-2015 08:55 PM

Originally Posted by ericpaulyoung

The limiting factor is maximum fuel delivery. The Motronic will adjust, but its ability to do so is limited. For a stock K03 style setup, it can probably adjust enough. For a K04 or higher, you will start hitting limits in the low pressure delivery system. Which is why Seth has a drilled pump etc. But yes, the Motronic adjusts to Lambda and not AFR, and is a great system. :)

epy

Seth is also running straight E85 and not a mixture. Adding 2 gallons of E85 to a tank won't hurt anything if your fuel system is functioning properly.

Edit: IIRC, the max adjustment it can make is +/-20%

**wootwoot** · 01-25-2015 08:57 PM

So no concerns with gaskets, seals, rings, or HPFP? Is anyone here mixing E85 with 91? Other than lower mpg do I have anything to worry about? I heard that a number of BMW drivers were running this mix, would that be the best place to find more information?

**ericpaulyoung** · 01-25-2015 09:11 PM

Originally Posted by wootwoot

So no concerns with gaskets, seals, rings, or HPFP? Is anyone here mixing E85 with 91? Other than lower mpg do I have anything to worry about? I heard that a number of BMW drivers were running this mix, would that be the best place to find more information?

Oh ya, definitely worry about that stuff. Just part of the game. E85 eats a lot of different stuff, and will also "flush" out your tank and lines. So all the gunk will end up in the injectors etc. But if you are pulling and cleaning your system right, you will be fine.

epy

**Andrew149** · 01-25-2015 09:13 PM

Found this post full of information http://www.e90post.com/forums/showthread.php?t=665920

**ericpaulyoung** · 01-25-2015 09:13 PM

Originally Posted by aluthman

Seth is also running straight E85 and not a mixture. Adding 2 gallons of E85 to a tank won't hurt anything if your fuel system is functioning properly.

Edit: IIRC, the max adjustment it can make is +/-20%

Yes, I agree. So look at what the volumetric mix will result in a 20% decrease in energy density, and boom, you got how much you can theoretically "cut" your petrol with corn and get away with it. But that is the theoretical amount, you can't actually achieve this. I would say go for a 15% change as a max.

epy

**mec** · 01-25-2015 09:17 PM

I heard that e85 with murder your mother and rape your father! Should I use only a 25/75% mix?

Should I mix by volume or by mass?

Should I invest in an e85 test kit so I can find out how much ethanol there really is in my e85? Should I Run e85 in my meth? FUKKKEKKEKEKKK

**Andrew149** · 01-25-2015 09:23 PM

I have e85 next to my house I'm curious by starting out with 2 gallons in my car

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**ericpaulyoung** · 01-25-2015 09:32 PM

Well the bitch of the situation is that E85 actually is like screwing the prom queen's sister. It is the methamphetamine of the cocaine racing scene. In no way is it as good as race gas, but people use it because it is CHEAP in comparison. The bad part is, well it may have high octane like race gas:

1. Corn has much lower energy density
2. Corn has serious corrosive properties

So in reality is it truly the poor man's racing fuel. B. U. T. that doesn't make it bad, it just means you have to take care to treat it properly. So where your rich friends are blowing through 7 gram rocks of glory with porn stars, you can have just as much fun pulling green vapor off tin foil hits and strippers. You just have to have the right mind set.

epy

**Andrew149** · 01-25-2015 09:35 PM

At the pump now

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**ericpaulyoung** · 01-25-2015 09:37 PM

Originally Posted by Andrew149

At the pump now

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Definitely only put 2-3 gallons in. And give it a few miles to adjust the fuel trim before stepping on it.

epy

**Andrew149** · 01-25-2015 09:38 PM

Originally Posted by ericpaulyoung

Definitely only put 2-3 gallons in. And give it a few miles to adjust the fuel trim before stepping on it.

epy

Sounds good

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**ericpaulyoung** · 01-25-2015 09:39 PM

Unless you are on a tune that requests more timing, you might not feel a difference. But, just remember that you are clearing your system of all the build up gunk. So give it a few flushes, and them put the "race gas" tune on and give it a shot. You should be able to push more timing before knock with little problems.

epy

**ericpaulyoung** · 01-25-2015 09:40 PM

May the force be with you brother!

epy

**RAudiB7A4** · 01-25-2015 09:42 PM

All I have run in the B7 for the last 3 years is BP 93, and I have E85 everywhere around me. I'm planning on switching to JHM soon but for now I'm on APR's 93 tune. I'm sure I couldn't mix enough E85 to get me to 100 octane for my race fuel tune from APR correct???

**Andrew149** · 01-25-2015 09:42 PM

Originally Posted by ericpaulyoung

Unless you are on a tune that requests more timing, you might not feel a difference. But, just remember that you are clearing your system of all the build up gunk. So give it a few flushes, and them put the "race gas" tune on and give it a shot. You should be able to push more timing before knock with little problems.

epy

For sure worse case is my fuel system gets cleaned

Originally Posted by ericpaulyoung

May the force be with you brother!

epy

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**ericpaulyoung** · 01-25-2015 09:44 PM

Originally Posted by RAudiB7A4

All I have run in the B7 for the last 3 years is BP 93, and I have E85 everywhere around me. I'm planning on switching to JHM soon but for now I'm on APR's 93 tune. I'm sure I couldn't mix enough E85 to get me to 100 octane for my race fuel tune from APR correct???

Yes. If you have not reached the limit of your fuel pump or injectors, then definitely you can.
epy

**mec** · 01-25-2015 09:44 PM

Originally Posted by Andrew149

Sounds good

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You have really expensive gas....2.09 gets me 91 octane!

**Andrew149** · 01-25-2015 09:45 PM

Originally Posted by mec

You have really expensive gas....2.09 gets me 91 octane!

Damn, this is at a cruisers so it's normally cheap

E85 is in the car and it started smoothly let's see what happens

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**derrek** · 01-25-2015 09:49 PM

When you talk and no ones listens.......

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**RAudiB7A4** · 01-25-2015 09:49 PM

I'm not sure if I have or not?! I've run the race fuel (100 octane) tune a few times, but always on 102 unleaded or 110 octane leaded fuels. I can get 110 octane leaded 5 miles from my work. I've ran about 15 gallons through the B7 without any ill-effects.

I have read that leaded fuels are most dangerous for clogging catalytic converters (which I don't have because test pipe), and hard on O2 sensors if you run to much of it.

But the 110 octane is like $8+ per gallon! E85 is around $2 per gallon.

**mec** · 01-25-2015 09:49 PM

Originally Posted by derrek

When you talk and no ones listens.......

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Dude I've been waiting for you! Where have you been?

Ladies and Gentlemen, the b7 resident e85 spokesman!

**derrek** · 01-25-2015 09:50 PM

Originally Posted by mec

Dude I've been waiting for you! Where have you been?

Ladies and Gentlemen, the b7 resident e85 spokesman!

been at the track raping my car all weekend

**Andrew149** · 01-25-2015 09:51 PM

Car feels like it gained a lot of torque

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**derrek** · 01-25-2015 09:52 PM

Originally Posted by RAudiB7A4

I'm not sure if I have or not?! I've run the race fuel (100 octane) tune a few times, but always on 102 unleaded or 110 octane leaded fuels. I can get 110 octane leaded 5 miles from my work. I've ran about 15 gallons through the B7 without any ill-effects.

I have read that leaded fuels are most dangerous for clogging catalytic converters (which I don't have because test pipe), and hard on O2 sensors if you run to much of it.

But the 110 octane is like $8+ per gallon! E85 is around $2 per gallon.

leaded fuel will clog cats and 02 sensors and you wont see any gains with it over 100 leaded unless you're tuned for the higher octane

**derrek** · 01-25-2015 09:54 PM

Originally Posted by Andrew149

Car feels like it gained a lot of torque

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how much did you mix?

**Andrew149** · 01-25-2015 09:54 PM

Originally Posted by derrek

how much did you mix?

2.5gallons and filled up the tank with 91

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**RAudiB7A4** · 01-25-2015 09:55 PM

Originally Posted by derrek

leaded fuel will clog cats and 02 sensors and you wont see any gains with it over 100 leaded unless you're tuned for the higher octane

Yeah I know that, but I can get leaded 110 octane fuel 5 miles from my work or get 102 octane unleaded 80 miles away... I can get E85 everywhere around me, and 93 octane with in 10 miles of my home. All I have run is 93 octane for the last 3 years.

**derrek** · 01-25-2015 10:00 PM

Originally Posted by Andrew149

2.5gallons and filled up the tank with 91

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so you should be around e22, i didn't notice to big of a difference when i ran that mix. I run e50-e60 now and use my race gas file. you should log your low pressure fuel trims, afr, and timing pull to see how its running.

Originally Posted by RAudiB7A4

Yeah I know that, but I can get leaded 110 octane fuel 5 miles from my work or get 102 octane unleaded 80 miles away... I can get E85 everywhere around me, and 93 octane with in 10 miles of my home. All I have run is 93 octane for the last 3 years.

are you getting at the pump or in 5gal drums from vp or sunoco