The Official Unofficial E85 Ethanol Thread

[Hoon]

130 cc/mn @ 3 bar will be 184 cc/mn @ 6 bar
https://www.raceworks.com.au/calculators/injector-flow-vs-fuel-pressure/

4 injector of 184 cc/mn at 90% duty cycle on E85 turbo engine can produce an extra 75Hp
https://www.raceworks.com.au/calculators/injector-hp-rating-calculator/

You have to consider relative pressure. If you have 6 bar fuel pressure and 2 bar of boost, you actually have 4 bar.

Wont lpfp pressure drop somewhat from 6 bar as total flow (hp+lp) increases? The MPI is fed directly by the lpfp right? So in the end perhaps 65 hp more or so?

Yes MPI is fed directly from the LPFP. If the pump is adequate you will have 6-6.5 bar MPI rail pressure, or about 4 bar relative pressure on 2 bar boost.

Aha intresting. As in asking Eurodyne to do the E85 tune or doing it oneself? With the ability to tweak boost and timing without reflash with the maestro (just learned about its existence, does one need to bring the laptop then?), maybe that is a way forward for daily usuability if ltft flex can be implemented. So does Eurodyne do E85, or how many here did their E85 tune themselves and are willing to share (is there a thread)?

Either way, my ROW ecu (with the factory MPI tables?) needs to be supported so that's the first question. What else to think about? Actually I do prefer to be in control of my mapping, just a bit comprehensive if I'm in over my head, this is not a simple ECU...

Thanks for the help so far all!

You would do the tuning yourself, Eurodyne is not going to write you a custom map. The E85 aspect is actually very simple, it's just a global fuel enrichment. This is a closed loop ECU so it does the fine tuning itself.

The rest is boost and timing adjustment for the additional fuel capability.

Obviously there's a lot more to the whole tuning process than that, but the E85 aspect alone is not complex.

 

[1hp]

You would do the tuning yourself, Eurodyne is not going to write you a custom map. The E85 aspect is actually very simple, it's just a global fuel enrichment. This is a closed loop ECU so it does the fine tuning itself.

The rest is boost and timing adjustment for the additional fuel capability.

Obviously there's a lot more to the whole tuning process than that, but the E85 aspect alone is not complex.

I thought I wanted a ready flexfuel tune, but actually if I can tune myself, that removes the necessity for flexfuel, as I will use E50-E85 99% of the time and can just reflash myself if I need to get by with gas by exception. The E60-E90 range regular fuel trim should take care of, and timing for E60 is probably as much as you can get anyway. I did my own E85 tune with open flash tablet on my '12 GT86, so some experience, but there was a big community for support. But I had a look in the Maestro thread and it seems there is a helpful critical mass so I might dare going for it. But before that, it has to work on my ROW ECU, will contact Eurodyne and find out....

 

[Hoon]

I thought I wanted a ready flexfuel tune, but actually if I can tune myself, that removes the necessity for flexfuel, as I will use E50-E85 99% of the time and can just reflash myself if I need to get by with gas by exception. The E60-E90 range regular fuel trim should take care of, and timing for E60 is probably as much as you can get anyway. I did my own E85 tune with open flash tablet on my '12 GT86, so some experience, but there was a big community for support. But I had a look in the Maestro thread and it seems there is a helpful critical mass so I might dare going for it. But before that, it has to work on my ROW ECU, will contact Eurodyne and find out....

You have a very good understanding already.

 

[1hp]

You have a very good understanding already.

We'll see about that, do I want to find out or not

Stupid question, but can one read and perhaps edit the stock file also, and not just stage 1/2 base files as needed to flash to unlock the ecu? I'd prefer to start with the stock file...

 

[1hp]

So waiting for eurodyne to answer.

Plan B if it the above is a no go (not very high hopes), my last option is to ask/assist my inexperienced tuner in making a ltft flextune. What are the stft/ltft limits? As an emergency running 93 I could accept a very negative ltft. Any ideas how to expand the range? Thanks

 

[1hp]

Total eurodyne silence.

Edit: I realise I don't know sh^t.

 

[anotero]

I have a question about mixing.

E-85 calculators for final ethanol content and octane number require absolute amounts of E-85 and regular gasoline inputs. When filling up at the pump, does the tank get filled up all the way to the declared 13.2 gallon capacity, or does the pump stop short of that? In other words, what is the exact capacity of a "full" tank when filling up to the first click?

 

[jimlloyd40]

I have a question about mixing.

E-85 calculators for final ethanol content and octane number require absolute amounts of E-85 and regular gasoline inputs. When filling up at the pump, does the tank get filled up all the way to the declared 13.2 gallon capacity, or does the pump stop short of that? In other words, what is the exact capacity of a "full" tank when filling up to the first click?

Depends if you are running the pump at full speed. I always set the nozzle to the medium notch and after it shuts off it will take another half gallon.

 

[anotero]

Depends if you are running the pump at full speed. I always set the nozzle to the medium notch and after it shuts off it will take another half gallon.

Half gallon to the point of it spilling out of the tank?

 

[Cliff p.]

I have a question about mixing.

E-85 calculators for final ethanol content and octane number require absolute amounts of E-85 and regular gasoline inputs. When filling up at the pump, does the tank get filled up all the way to the declared 13.2 gallon capacity, or does the pump stop short of that? In other words, what is the exact capacity of a "full" tank when filling up to the first click?

Assuming a MK7 R tank is 15.5gal, I always divide the “required refuel quantity” in my dash by the total capacity. Then I use that percentage to calculate my required fuel mix. I only go up to those values, usually overshooting the E blend by 1 point. That way if I have a bit less to fill than the gauge said, I’m still within my required blend


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[anotero]

Assuming a MK7 R tank is 15.5gal, I always divide the “required refuel quantity” in my dash by the total capacity. Then I use that percentage to calculate my required fuel mix. I only go up to those values, usually overshooting the E blend by 1 point. That way if I have a bit less to fill than the gauge said, I’m still within my required blend


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But the required refuel quantity in the dash is not very accurate. It's only given as whole numbers, and even though it may display 7 gal, you done know how close that is to 7 or 8.

 

[Cliff p.]

But the required refuel quantity in the dash is not very accurate. It's only given as whole numbers, and even though it may display 7 gal, you done know how close that is to 7 or 8.

I’m okay with not having 100%


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[anotero]

I’m okay with not having 100%


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In that case, what is an acceptable deviation from the ideal target octane number achieved by mixing? Say i need 93 octane, and to do that I'm mixing 91 with E85. Is having 92 acceptable? I'm sure I can get it closer than that, but want to be aware of the margin i have.

 

[jonnyg]

I have a zeitronix eca and conti gauge. In my area the E85 is consistently 70-75 %
I find the "refuel quantity" in MFD is fairly accurate. At around 11+ gal mark, I fill up with 4 gal E85 and top off with 93 (7-8 gal) and get E30 (typically 28 to 32 on zeitronix)

Since the ethanol content varies so widely, really need to test if you want your blend to be consistent

 

[anotero]

I have a zeitronix eca and conti gauge. In my area the E85 is consistently 70-75 %

I find the "refuel quantity" in MFD is fairly accurate. At around 11+ gal mark, I fill up with 4 gal E85 and top off with 93 (7-8 gal) and get E30 (typically 28 to 32 on zeitronix)



Since the ethanol content varies so widely, really need to test if you want your blend to be consistent

I tested the E85 from station i fill up at, and it's consistently 83%, so pretty much as pure as it gets. However the question still stands: how full is a mk7 tank when the gas pump stops pumping? Using the dash refuel quantity has a margin of +/- 0.5 gal, i assume.