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  1. #1
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    Mixing E85 with E10 fuels

    Now, before you jump on me about searching E85, I've done the searching part and I have found some interesting things.. It appears that there are a lot of people who are very very confused about E85 and blending it with regular E10 gasolene.

    I then went and started digging online for E85 blending calculators and every single one of them are using the wrong numbers so it seems to me that people are getting very mixed up results when they are blending their fuels. The assumption is that the vast majority of people assume that E85 has octane rating of 105 which is incorrect!

    All gasolene fuels sold at the pumps in USA have their octane rating measured based on the AKI scale, or Anti-Knock Index. The premium fuel sold in the states has AKI of 93 and has RON of 97. The E85 has AKI of 96 and RON of 105. A lot of people think that E85 has AKI of 105, which is totally wrong.

    Here is the source:
    http://en.wikipedia.org/wiki/Octane_rating

    Scroll down to the table with the different fuels.

    So, considering a 16 gallon tank (empty), a mix of 4 gallons of E85 and 12 gallons of Premium (E10) will result in 16 gallons with AKI of 93.8

    Explain to me again, why are so many people jumping on the E85 bandwagon when we have seen explicit communication from a BOSCH engineer that E85 can cause damage to the fuel injectors?
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  2. #2
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    Because it works for them? They're mixing it 50/50 with pump
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    Click here to enlarge Originally Posted by dzenno Click here to enlarge
    Because it works for them? They're mixing it 50/50 with pump

    Works in what ways? 50/50 mix of 8 gallons of E85 and 93 AKI will get you 16 gallons of fuel with 94.5 AKI.

    In comparison, just 3 gallons of race fuel with AKI of 100 mixed with 13 gallons of AKI 93 will net you the exact same 16 gallons of 94.5 AKI, WITHOUT having to worry about the fuel injectors.
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    Works as in when they do a run on high boost they get very little to no timing retard compared to before...but i see where you're going with that...i'm glad I have 94 octane pump up here
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    Right, that is good info Vas but as dzenno pointed out about little to no timing retard so it appearsto be working and be much more consistent. Even our most famous salesman said he was within 5 whp after 5 or so pulls...

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    Click here to enlarge Originally Posted by Q4P Click here to enlarge
    Right, that is good info Vas but as dzenno pointed out about little to no timing retard so it appearsto be working and be much more consistent. Even our most famous salesman said he was within 5 whp after 5 or so pulls...

    True. My only concern is that there are going to be a lot of sheep who will start blending E85 and AKI 93 and bumping their boost and timing advances because they think they have much higher octane fuel than they actually do. Just take a look at the big post from benzu89 on the Cobb Technical thread to see what I mean.
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  7. #7
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    Click here to enlarge Originally Posted by Q4P Click here to enlarge
    Even our most famous salesman said he was within 5 whp after 5 or so pulls...

    Isn't Lord Voldemort running pure E85 though? For this, Cobb users would need a proper map or ATR to make the car run correctly, no? Also, pure E85 sounds like too much of a risk for just a few HP...
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    Click here to enlarge Originally Posted by vasillalov Click here to enlarge
    Isn't Lord Voldemort running pure E85 though? For this, Cobb users would need a proper map or ATR to make the car run correctly, no? Also, pure E85 sounds like too much of a risk for just a few HP...
    Afaik, no one is running straight E85 although i would love to see that.

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    Nah, no one is running E85 straight
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    Anyone running pure E85 on the N54 is asking for it. You simply cannot flow enough E85 through the stock system to run a safe AFR consistently, and you can't upgrade the components that would allow you to get to that good AFR.

    There are lots of guys on different platforms (Mitsu, Suby) that run 100% corn, but they always upgrade pump, injectors and tune at a minimum to do so.

    As for the perceived risk, some people have more ready access to E85 than they do race fuel, so there really is no other option for safely upping boost except meth. I think it could be argued that the risks between meth and E85 are about equal if you believe our Bosch engineer friend.
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    I guess I can see how blending E85 with AKI 91 in Arizona, California, Nevada makes a noticeable difference. Those users can run the aggressive maps from Cobb. But for the rest of us who have access to 93 and even 94 AKI fuels, I honestly don't see a big benefit. ...at least not on paper.

    I am tempted to give it a try. I'll try first a mix of 2 gallons of E85 mixed with 14 gallons of AKI 93 and see if there is any difference in the logs...
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    2 out of 2 members liked this post. Yes Reputation No
    You are forgetting that E85 has a cooler intake charge. Here is a description on wiki. About halfway down.

    So yes the effective octane may not be as high as you think. But the fuel itself is different thus having different chemical properties. The cooler intake charge helps a lot to cool the cylinder temps and decrease the chance of knock. That is why it makes more power than a similar octane rated gas.

    http://en.wikipedia.org/wiki/E85

    Some vehicles can actually be converted to use E85 despite not being specifically built for it. Because of the lower heating value E85 has a cooler intake charge—which, coupled with its high stability level from its high octane rating—has also been used as a "power adder" in turbocharged performance vehicles. These modifications have not only resulted in lower GHG emissions, but also resulted in 10-12% power and torque increase at the wheels. Because of its low price (less than $2.00/gal in some places) and high availability in certain areas people have started to turn to using it in place of high-end racing fuels, which typically cost over $10.00/gal.

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    ^^^ +1 There are 2 components to octane: ignition temp and cylinder cooling. Alcohol has much better cooling properties then gasoline. I suspect this is causing an increased octane rating with this blend then the calculated mass ratio.

    There’s a guy on here that worked for octane rating facility that would be able to much insight.

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    Aaaah, I see now. You go for the double benefit of AKI increase and charge cooling! I guess I'll give it a try this weekend as my gas tank is nearly empty. I have an E85 station 2 miles from my condo.
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    Here is more information on LHV or Lower Heating Value. Since E85 has a lower heating value (Meaning it burns cooler when combusted) it requires more fuel to be sprayed in order to achieve the same btu energy of burning gasoline.

    This is in a sense over fueling the cylinder and cooling it down like a fire hose on a house. So the more E85 the more of the effect. But like you have all mentioned, I am not so sure our fuel system is up to that challenge quite yet. That is why the 50/50 blend is being used. Plus it's much easier for people to blend at a 50/50 ratio. And for those of us living in California with crap 91 this nice little bump to 94-96 octane is a noticeable help too.


    http://en.wikipedia.org/wiki/Lower_heating_value#Lower_heating_value

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    Other things I've discovered that make me bit weary about pure E85:

    E85 ethanol is used in engines modified to accept higher concentrations of ethanol. Such flexible-fuel vehicles are designed to run on any mixture of gasoline or ethanol with up to 85% ethanol by volume. There are a few major differences between FFVs and non-FFVs. One is the elimination of bare magnesium, aluminum, and rubber parts in the fuel system. Another is that fuel pumps must be capable of operating with electrically conductive ethanol instead of non-conducting dielectric gasoline fuel. Fuel-injection control systems have a wider range of pulse widths to inject approximately 34% more fuel. Stainless steel fuel lines, sometimes lined with plastic, and stainless-steel fuel tanks in place of terne fuel tanks are used. In some cases, flex fuel vehicles use acid-neutralizing motor oil. For vehicles with fuel-tank-mounted fuel pumps, additional differences to prevent arcing, as well as flame arrestors positioned in the tank's fill pipe, are also sometimes used.
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    I literally just read that too. But some guys have been running E85 mixes for some time now so that makes me feel better. I am really dying to try out E85.

    I don't think sporadic use can cause to much harm right?

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    Click here to enlarge Originally Posted by (-(ellblazer420 Click here to enlarge
    I literally just read that too. But some guys have been running E85 mixes for some time now so that makes me feel better. I am really dying to try out E85.

    I don't think sporadic use can cause to much harm right?

    ...I don't know man. We weren't seeing meth fires from WW tanks right from the start when they were first offered. It took a while for the community to realize that the WW tank is not a good choice for storing methanol.

    I wonder when we will see the first E90 exploding because some idiot put pure E85 and his in-tank fuel pump sparked.

    That being said, I don't think that 2 or 4 gallons of E85 mixed with E10 will be THAT dangerous...
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    2 out of 2 members liked this post. Yes Reputation No
    If you are really concerned about materials compatibility, then get your mix ratio down to E25 in your tank. That is what Brazil has been using for nearly 20 years, and the BMW units sold there are exactly the same as those sold in Europe.
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    Click here to enlarge Originally Posted by whoosh Click here to enlarge
    If you are really concerned about materials compatibility, then get your mix ratio down to E25 in your tank. That is what Brazil has been using for nearly 20 years, and the BMW units sold there are exactly the same as those sold in Europe.

    Good to know!
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    Click here to enlarge Originally Posted by whoosh Click here to enlarge
    If you are really concerned about materials compatibility, then get your mix ratio down to E25 in your tank. That is what Brazil has been using for nearly 20 years, and the BMW units sold there are exactly the same as those sold in Europe.
    Interesting. So if BMW produces cars that can run higher Ethanol content in other countries maybe the materials in the trunk are slightly over engineered to make the cars universally safe?

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    I want to see the results of the first cobb ap protune on 50/50 e85... someone get on it.

  23. #23
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    I would certainly hope so! And this also means that there is a decent amount of head room in the IPW
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  24. #24
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    Click here to enlarge Originally Posted by (-(ellblazer420 Click here to enlarge
    Interesting. So if BMW produces cars that can run higher Ethanol content in other countries maybe the materials in the trunk are slightly over engineered to make the cars universally safe?
    That would be my expectation. The "Changes in Gasoline" pdf that is linked from the wiki article cited above even talks about increases in the US from E10 to Exx in the future. I doubt manufacturers engineered up to 10% and then stopped, especially with Brazil already at E25.
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    OK I am sold. E85 maps going on the car this weekend. 50/50 blend seems pretty safe to me.

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