Cobb and E85 Mixtures

[fabian]

hey,

just thinking about getting an eTune from protuningfreaks for a second map with a E85 mix.
For Example 30% E85.

but as I only want to use the Cobb, how can I ensure that I allways have a healthy 30% mix of E85 in my gastank?

I think the BEST way would be to mix it at the gasstation:
- 7Liters normal gasoline (100 or 102 RON)
- 3Liters E85
- 7Liters gasoline
...

and so on, but that is not workable... I don`t want to transport 15L of E85 in 3L servings and it would be a long process ;-(

How do you guys with Cobb and E85 Mix maps handle this problem?
Or will the engine mapped to a bit weaker E85 Mixture to compensate that the mixture is not allways exactly the same?
But the question how to ensure that it is properly mixed in the gastank is still the same?

[135Pats]

I don’t know of any surefire way to do it other than what you mentioned, more or less. I rarely run ethanol, but when I do I just run the current tank empty, fill however many gallons of e85 and the rest 93 pump. You get into trouble when you start adding pump or e85 to a tank that’s not empty, so just run each tank to the bottom and start over. It’s not perfect, but you can get pretty darn close to your target. Also remember that in the winter months, at least in the ‘States, E85 is really more like E70.

[Ænema]

Winter is the best time to get/do tuning. "e85" will be closer to "e70" so that means that as the gas stations start getting stronger ethanol blends the tune will actually run better and tune adjustments shouldn't be necessary, or if they are it will be minor.

As long as you put in 5 gallons of "e85" and then finish filling the tank with gasoline you will be close enough to e30.

[b1aze]

It's really not hard at all. And honestly, you should be a bit more worried about the actual ethanol content of the E85 rather than the proper mixing ratio. IIRC, E85 can range from 65% to 90% ethanol.

So to properly proportion your tank when it's not completely empty, you first need to know your fuel capacity. I think the E82 platform is 14gal. That's close enough for our calculations.

If you want to run 30% E85, a full yak will take 4.2gal of e85, the rest 93 (or better).

If you have, say, 1/4 tank left, you have about 11.5gal space available. 3.45gal E85 and the rest 93.

There is no harm in running MORE ethanol than you're tuned for. There is harm in running SIGNIFICANTLY less than desired. A little bit can be accounted for by the DME and will tune itself out.

[JZWBMW]

I am running E30 in my current set up with my tune and stg 3 hw and it can be confusing, a calculator will help :-) If you are half tank and feel you are mixed 30% already, you can in theory, calculate out the fill up mixture. You will add 7 new gallons, 7x.30= 2.1 gallons, the rest gasoline. Problem is that is a E85% mixture or E70% mixture, so the math has to be correct for what you are trying to do.

On a empty tank, I get 4.2 gallons of E85 to be 30% ethonal, but in the winter on a E70 mix, it needs to be 5 gallons. I went all the way to 6 gallons and ended up near a E40 mix and see fuel trims in the 23-25% range, getting close. It will throw a cel for stft being out of range if it maxes out the fuel trims. Safter to have more ethonal for an aggressive timing map with a tune. I always try to go to the side of more ethonal, safer for knock protection and even if it leaned out a little under WOT, I am not as worried with ethonal.

JZW

[brusk]

If your only shooting for an E30 tune I would just use the OTS E30 Map. Fill up for what you think is an E30 mixture and go log. If your getting timing corrections add more E85 until your logs are clean. Then pop out the back seat and pull a sample from the tank on the passenger side to see what mix your tune liked. After this you can sample the E85 and 93 octane pumps you frequent to get decent numbers for you calculations. I also check my in tank mix every other fill up to make sure it's where it should be. I also don't have easy access to E85 so store 30 Gallons in my garage. BTW in Dallas my E85 was E89.3 and the 93 pumps ranged anywhere from E2 to E12 on the same week at 5 different local stations so I would usually shoot for the worst calculation to give me more Ethanol in my mix that what my tune required.

[fabian]

Thanks guys!

but how do you handle the tank up? Fill in the calculated E85 part and then the rest with normal gasoline? will it blend to an even mixture?

I think I would be to scared and see me ending in driving half of my tank empty with hard breaking and cornering to mix the blend in the tank to an even mixture before I do WOT runs

for the Ethanol consistent in the E85 I`m planing to buy E100 (if I can get it) and mix it at home, as the next E85 gas station is about 1/4 tank away from me ;-)

Originally Posted by brusk

Then pop out the back seat and pull a sample from the tank on the passenger side to see what mix your tune liked.

and how do I know which mix it is?

[brusk]

I prefer to put E85 in first and with the bucket design that's in the tank and the way it sends fuel back and forth I've heard 10 minutes is what it takes to get everything mixed properly. I don't mind some side to side weaving to help though.

[Gimlet]

So I've asked before but I want to be certain before I run this, as the answers i got just left me confused. I have access to 100% petrol 93, and E85 and E100 (all at the same station about 2 miles away ). Edit - this is to run the E30 OTS map.

With the full-petrol 93, I am thinking I run 4.2gal of E100? Or is that over doing it? Based on my math that should give me a pretty close to perfect E30 blend.

Whereas if I was using say 93 that was E10, then I would use the E85 at the same ratio.

I would be more comfortable running the pure petrol and E100, since I would have much more confidence in the end result being what I calculated...Just not sure if that is the correct route.

Can someone advise?

[Ænema]

Originally Posted by Gimlet

So I've asked before but I want to be certain before I run this, as the answers i got just left me confused. I have access to 100% petrol 93, and E85 and E100 (all at the same station about 2 miles away ). Edit - this is to run the E30 OTS map.

With the full-petrol 93, I am thinking I run 4.2gal of E100? Or is that over doing it? Based on my math that should give me a pretty close to perfect E30 blend.

Whereas if I was using say 93 that was E10, then I would use the E85 at the same ratio.

I would be more comfortable running the pure petrol and E100, since I would have much more confidence in the end result being what I calculated...Just not sure if that is the correct route.

Can someone advise?

Yep, that should work just fine. Be sure to datalog to confirm everything is as it should be.

[1911A145]

http://www.zeitronix.com/Products/ECA/ECA.shtml

[1911A145]

Why do you all keep "guessing" and taking samples of the gas by removing the back seat (LOL) and all these mixting ratios, etc.

Just buy piece of mind and be done with it already.

There are a ton more videos out there like this one. :

[JZWBMW]

I am running E30 and even up to E40 on my own car now and since I have changed the fueling constant, the car runs much better and the way I look at is that its better to be over the ratio with ethonal than under. I am running a good bit more timing in my tune and the car makes great power. I would rather it be a higher mixture of ethonal than under to keep the knock protection up.

With Ethonal, you can get away with much leaner air fuel mixtures, so if you are calculating your mixture, I would recommend going on the side of more ethonal than less ethonal, have been up to 40% now and no issues with my tune. Without the tune it will throw a cel for the trims being out of whack :-)

JZW