My experience with a tankful of E-85 fuel

[Kreepin1]

I got a Livernois flex fuel tune over a year ago and have been running exclusively on E85 ever since without any issues. Here's the straight scoop.

The fuel system on our 3.6 Wranglers (tank, pump, lines, injectors) is compatible with E85. However, the computer's fuel map is not. Livernois' tune extends the fuel map to cover E85 and adjusts the ignition timing to take advantage of the increase in octane.

Human's talk about air/fuel ratio domain (lbs of air to lbs of fuel) as a holdover from the old days of carburetors and we get confused thinking about ethanol with 30% less energy content than gasoline. But computers work in the lambda domain provided by the O2 sensor. They are blind to the fuel in the tank and only worry about the exhaust. When you filled up with E85 the computer kept increasing injector pulse width to get to an acceptable O2 level. It kept doing this until it ran off the edge of it's fuel map at which point it went into limp mode, and yes, it was still too lean.

Too be clear, the stock injectors have plenty of capacity for normally aspirated operation on E85. It is the computer map that doesn't.

Assuming a proper tune, our engines run cooler on E85. This is due to the cooling effect of evaporation and a better ignition advance curve.

Sponsored

 

[Kreepin1]

I really only ran thru 1/2 tank. Now I’m running a blend of 91 octane non ethanol and the E-85, which I figure is about equal to the 87 octane 10% ethanol she is use to running on.

I'm not sure why you are doing this, but you should be aware that the amount of ethanol in E85 varies seasonally. Around here it's about 80% in the summer and drops into the 50-60% range in the winter.

To get a 10% blend you should combine 2 gallons of E85 with 14 gallons of ethanol free gas. The octane will be around 93. This assumes you are starting with E85 that is 80% ethanol and 91 octane ethanol free gas.

 

[azjl#3]

E85 is actually MUCH higher in octane, generally around 105.

That is why PROPERLY PREPPED AND TUNED vehicles make more power on E85. Especially turbos.

Remember that octane is a measure of the fuel's resistance to detonation. This allows more aggressive ignition timing and A:F ratios. In turbo engines it allows for more boost.

By properly prepped I mean larger injectors if necessary since there is less energy per volume in alcohol. So for a given air:fuel ratio, you need more fuel. Which then obviously means that you need at least a tune to run it.

A flex-fuel vehicle has an alcohol sensor so it can tell how much alcohol is in your fuel and meter the fuel accordingly.

That garage show tested this and many fuels and found e85 was cheap and made as much power as race fuel.

 

[dcmdon]

That garage show tested this and many fuels and found e85 was cheap and made as much power as race fuel.

Absolutely. That makes total sense since the Octane rating of ethanol is about 105. But the vehicle has to be able to take advantage of it.

At the very least it needs to be tuned to run much richer because the stoichiometric A:F ratio of ethanol is different than gas.

Ethanol is 9:1, whereas gas is 14.7:1.

If your stock fuel pump, fuel pressure regulator, and injectors can handle it, then you can get off cheap. But you may need to upgrade any combination of those items to provide adequate fuel flow at full throttle.

 

[Kreepin1]

At the very least it needs to be tuned to run much richer because the stoichiometric A:F ratio of ethanol is different than gas.

Ethanol is 9:1, whereas gas is 14.7:1.

Modern fuel injection systems are tuned with an O2 sensor so you have to be careful when you say it needs to run much richer. In the lambda domain stoich is 1.0 regardless of if you are running gas, ethanol or a blend. It is true that it takes significantly more ethanol to get there.

If your stock fuel pump, fuel pressure regulator, and injectors can handle it, then you can get off cheap. But you may need to upgrade any combination of those items to provide adequate fuel flow at full throttle.

Absolutely, and the JL Wrangler's fuel system is up to the task. I heard a rumor that this is because one of the original design goals was to export them to Brazil where they run E98 and E100.

 

[dcmdon]

Modern fuel injection systems are tuned with an O2 sensor so you have to be careful when you say it needs to run much richer. In the lambda domain stoich is 1.0 regardless of if you are running gas, ethanol or a blend. It is true that it takes significantly more ethanol to get there.


Absolutely, and the JL Wrangler's fuel system is up to the task. I heard a rumor that this is because one of the original design goals was to export them to Brazil where they run E98 and E100.

So you are telling me there is no open loop mode?? No pre-set maps??

I'm a bit behind the times on tuning so this may be a dumb question.

 

[Kreepin1]

So you are telling me there is no open loop mode?? No pre-set maps??

I'm a bit behind the times on tuning so this may be a dumb question.

Not what I'm saying at all. I'm saying once you realize the new reference is the O2 sensor you can pretty much ignore what fuel is being used. Here is the back story...

My first experience with E85 started a few years ago when I built a 401 for my CJ-7. Bored and stroked to 416 cubic inches, 11.3:1 compression, roller cam that leans more to low-mid range torque than high rpm power... and the relevant point is Edelbrock's Pro Flo 4 sequential port fuel injection system which it's really cool to see them supporting an engine made in 1975.

But, just like our JL Wranglers, the Pro Flo 4 does not support E85 even though all the bits and pieces are E85 compatible. So you are on your own for tuning. I bumped injectors up one size and calculated the correct fuel pressure to get the system in the ballpark with one of Edelbrock's E10 fuel maps. Then took the engine out to a local dyno shop. They do mostly truck and tractor pull stuff and all of it carbureted. So I fired up the tuning app and they had me set it as rich as it would go, since, like you say, A/F for E85 is like 9.3:1. They were really worried we'd burn a valve since the lowest it would go was like 11:1. So we adjusted the timing curve for max power and I went out the door. Once the engine was in the Jeep I spent some time breaking it in and on the first long drive bent a valve. Crap. Turned out one of the cam bores was oversized from the factory and the bearing spun.

So I sent the engine to the guy that did the heads in North Carolina. He had just set up his own dyno. We fired it up and on the first pull back fired so hard it shot the guts of the muffler into his back hard. Super strong smell of fuel. So we kept leaning it out and making more an more power until we were in the typical A/F range for gasoline. Best pull was 472 HP at 5,200 rpm and 508 ft-lb at 4,300 rpm (457 HP and 492 ft-lb corrected). Whaaaat?

It finally clicked. The fuel injection system is working in the lambda domain. Then it converts that to the gasoline A/F domain and displays it. So when I see 14.7 during cruise conditions the fuel system is really delivering 9.3.

 

[JKWMD]

My last Audi was tuned for E85; great stuff, but as others have said, you need to have a specific tune and several other modifications to run it safely. I hope everything works out, but keep your fingers crossed there is no permanent damage.

 

[AFD]

The 3.6 is in no way rated for ethanol fuel and should use the lowest concentration available at any given location.

Long term damage may yet be found from this. A half a tank is a long time to be running that crap, it burns hot.

As @azwjowner already mentioned, it's rated for up to E15 (aka Unleaded 88), but nothing higher, like E85. Not that I'd recommend running either, and I absolutely agree that it's best to use the lowest amount available). Not sure if a single tank of E85 would cause any major issues, but I'd be most concerned about potentially voiding your warranty if any temporary issue was explained to a dealer (ie, codes thrown from running in lean mode)..

 

[BrntWS6]

Yellow gas cap signifies an E-85 or flex fuel vehicle. I run e-85 but have a livernois tune. Its a great alternative when regular is $4.00/ gal and E-85 is $2.50/ gal.

 

[Pinky Tuscadero]

No one else said it so I will...
That was a pretty stupid thing to do
And I specialize in doing stupid things so.....

 

[dcmdon]

Not what I'm saying at all. I'm saying once you realize the new reference is the O2 sensor you can pretty much ignore what fuel is being used. Here is the back story...

My first experience with E85 started a few years ago when I built a 401 for my CJ-7. Bored and stroked to 416 cubic inches, 11.3:1 compression, roller cam that leans more to low-mid range torque than high rpm power... and the relevant point is Edelbrock's Pro Flo 4 sequential port fuel injection system which it's really cool to see them supporting an engine made in 1975.

But, just like our JL Wranglers, the Pro Flo 4 does not support E85 even though all the bits and pieces are E85 compatible. So you are on your own for tuning. I bumped injectors up one size and calculated the correct fuel pressure to get the system in the ballpark with one of Edelbrock's E10 fuel maps. Then took the engine out to a local dyno shop. They do mostly truck and tractor pull stuff and all of it carbureted. So I fired up the tuning app and they had me set it as rich as it would go, since, like you say, A/F for E85 is like 9.3:1. They were really worried we'd burn a valve since the lowest it would go was like 11:1. So we adjusted the timing curve for max power and I went out the door. Once the engine was in the Jeep I spent some time breaking it in and on the first long drive bent a valve. Crap. Turned out one of the cam bores was oversized from the factory and the bearing spun.

So I sent the engine to the guy that did the heads in North Carolina. He had just set up his own dyno. We fired it up and on the first pull back fired so hard it shot the guts of the muffler into his back hard. Super strong smell of fuel. So we kept leaning it out and making more an more power until we were in the typical A/F range for gasoline. Best pull was 472 HP at 5,200 rpm and 508 ft-lb at 4,300 rpm (457 HP and 492 ft-lb corrected). Whaaaat?

It finally clicked. The fuel injection system is working in the lambda domain. Then it converts that to the gasoline A/F domain and displays it. So when I see 14.7 during cruise conditions the fuel system is really delivering 9.3.

That's really interesting. Thanks for the write up.

 

[KuntryRube]

I'm gonna have to chime in on this as I see there are a lot of naysayers and people ignorant of the benefits of E-85 although I don't blame them. I just wish people would be well-informed.

I say this all the time. I am a firm believe that alcohol is the best way to go in every factor. The benefits far outweigh the cons. Honestly, the only thing that is "bad" would be the increased need of fuel to have a full combustion with a good AFR. The byproduct of that is lower gas mileage. You need about 30% more e85 than you would gasoline 1 for 1. So all things considered, newer vehicles really only need to look at the injector sizes and possible LPFP and HPFP if you have a DI vehicle. I use to run full e85 on my Evo X and my F82 M4 and both were pushing high horse power for years - None of them failed. And I am going to make a statement that for those that don't believe in e85 that will blow your mind.

Running e85 with Methanol/water injection is MUCH safer that running e10 or worse pure gasoline.

"Whaaaaaaatttttt???!?!!!" you might say. Well that's because you don't know or haven't looked deeply into this area. The guys that know what I am talking about can pitch in and will agree with me here. The timing advance can be pushed to very high due to the incredible knock resistance of that combo. The engine burns much much cooler and there is absolutely no carbon deposits. My buddy who ran an e85 tune with an Evo 8 tore down his engine after 3000 miles to upgrade his pistons and his short block was as clean as a new engine before it was put into a frame. We dumped the oil that was 3000 miles old and it was see-through. His valves were new looking because it was port injection, the e85 cleaned his valves.

E85 really is a great fuel. People just have to get over the stigma that's going around.

I plan on running e85 once I get my 392 only because it's really great for the motor. I won't be turning up the power or torque since the rods are weak on the 6.4 hemi.

 

[mwilk012]

I'm gonna have to chime in on this as I see there are a lot of naysayers and people ignorant of the benefits of E-85 although I don't blame them. I just wish people would be well-informed.

I say this all the time. I am a firm believe that alcohol is the best way to go in every factor. The benefits far outweigh the cons. Honestly, the only thing that is "bad" would be the increased need of fuel to have a full combustion with a good AFR. The byproduct of that is lower gas mileage. You need about 30% more e85 than you would gasoline 1 for 1. So all things considered, newer vehicles really only need to look at the injector sizes and possible LPFP and HPFP if you have a DI vehicle. I use to run full e85 on my Evo X and my F82 M4 and both were pushing high horse power for years - None of them failed. And I am going to make a statement that for those that don't believe in e85 that will blow your mind.

Running e85 with Methanol/water injection is MUCH safer that running e10 or worse pure gasoline.

"Whaaaaaaatttttt???!?!!!" you might say. Well that's because you don't know or haven't looked deeply into this area. The guys that know what I am talking about can pitch in and will agree with me here. The timing advance can be pushed to very high due to the incredible knock resistance of that combo. The engine burns much much cooler and there is absolutely no carbon deposits. My buddy who ran an e85 tune with an Evo 8 tore down his engine after 3000 miles to upgrade his pistons and his short block was as clean as a new engine before it was put into a frame. We dumped the oil that was 3000 miles old and it was see-through. His valves were new looking because it was port injection, the e85 cleaned his valves.

E85 really is a great fuel. People just have to get over the stigma that's going around.

I plan on running e85 once I get my 392 only because it's really great for the motor. I won't be turning up the power or torque since the rods are weak on the 6.4 hemi.

Exactly how much farmland do you own producing corn?

 

[KuntryRube]

Exactly how much farmland do you own producing corn?

I used to patronize all of the corn farmers of the midwest and eastern United States by buying their ethanol. I don't at the moment though. I buy all the prince's oil over in Dubai :P

Sponsored