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E85 race fuel

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I'm curious - as far as I know no one is using this fuel to their advantage. I just checked the AMA rule-book and it sure looks legal to me (for amateur racing at least).

I know this fuel isn't viable as an "eco-friendly" (:ride:) fuel, but it makes an awesome race fuel. This is especially true in forced-induction applications, or engines with extremely high compression ratios.

There are quite a few Lancer Evolutions with 12:1 - 13:1 CR and 30+ psi of boost being driven on the street making some staggering HP/ TQ numbers. :worthy: I bet if someone was crazy enough to build a MX engine specifically to run E85 you could have one hell of a machine on your hands.

Also, for you 2-stroke guys (like me 👍) I've heard that Klotz R30 mixes well in E85 and stays suspended!

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yes, that's what he's talking about, but to use it in cars you get big hp but you have to run big injectors

e85 is getting popular in autocross and time trial road racing becuase they dont dock many points for it, and you get a lot of hp

hard to do with carbs, but more and more FI bikes now

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i tried this a year or so ago on my yz250f. i got it to where it ran ok, really lean at the point yet tho. and at that point i couldnt find any jets big enough. looked into going with street bike/snowmobile carb jets but gave up before hand. one problem i ran into was the accelerator pump plunger (black rubber piece) actually looked like it was breaking down or melting after a couple full tanks of it, something to look into. also tried just drilling out spare jets i had after i couldnt buy them bigger, got to the point where only bit i had bigger was bigger than the jets haha. definately curious wat you have in mind. my motor was also port nd polished with hc piston as well

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also, it ran the motor really dry so i did use a little premix in the fuel to try to compensate. not much tho

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Well, pardon me, but ethanol is frankly a rather poor engine fuel. It has a decidedly inferior energy content on a BTU/mass basis, and the only real advantage to it is that it can be run with extremely high compression ratios.

Stoichiometric AF ratio with ethanol is 9:1 as opposed to 14.6:1 with gasolines (in general), so I'm assuming that E85 would be at 10:1 or thereabout just to begin with, and probably richer for good power. Dynos have shown over and over that straight ethanol offers little or no gain over gasoline unless advantage is taken of its high tolerance for compression.

Then there is the whole problem of its hygroscopic nature. Ethanol has a high affinity for water, to the extent that it draws it out of the air that it's exposed to. Water mixes with it quite well, and causes no immediate problems in small amounts, but it reduces the energy content per mass volume even farther.

Plus, it's hard on fuel system parts. I'm going with a fat "no" on this one. Corn belongs at my BBQ, not in my fuel tank.

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also, it ran the motor really dry so i did use a little premix in the fuel to try to compensate. not much tho
This is a necessity with methanol (which is a much more productive fuel), also. The fuel is all that lubes the top cylinder, and alcohols are not good at that.

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all I know is they run almost double the injector size, ie 220cc to 450cc

indy and a few american LeMans teams run it now, and it's popular in autocross and timetrials

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Well, pardon me, but ethanol is frankly a rather poor engine fuel. It has a decidedly inferior energy content on a BTU/mass basis, and the only real advantage to it is that it can be run with extremely high compression ratios.

Stoichiometric AF ratio with ethanol is 9:1 as opposed to 14.6:1 with gasolines (in general), so I'm assuming that E85 would be at 10:1 or thereabout just to begin with, and probably richer for good power. Dynos have shown over and over that straight ethanol offers little or no gain over gasoline unless advantage is taken of its high tolerance for compression.

All this is right on, but I dont see any of these as negative aspects. Most E85 fuel maps that I've seen are around 11.2-11.6:1. Obviously fuel economy is crap- but its a race bike! If you want to take advantage of this fuel you NEED to build the engine for it (thats like saying "my kia doesn't make more power on C16- therefore C16 is not a good fuel", isnt it?)

Then there is the whole problem of its hygroscopic nature. Ethanol has a high affinity for water, to the extent that it draws it out of the air that it's exposed to. Water mixes with it quite well, and causes no immediate problems in small amounts, but it reduces the energy content per mass volume even farther.

From what I've seen this isn't that big of a problem. I know that some users get deposits in their injectors, but it seems to be far and few between. Even though E85 contains less energy than gasoline you are burning more fuel than before. If timing is advanced and compression ratio increased accordingly you WILL see a power increase.

Plus, it's hard on fuel system parts. I'm going with a fat "no" on this one. Corn belongs at my BBQ, not in my fuel tank.

I know that in EFI applications the fuel system seems to hold up fine, aside from the "gunk" I mentioned before. I have zero experience with E85's compatibility with carbs - I do know that neoprene gets along well with ethanol. Most seals are readily available made of neoprene.

👍

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As long as one understands that the fuel is not a single source power increase from which you can get big gains just by dumping it in the tank and jetting for it (as is the case with a good race gas vs. pump) then that's one thing. It clearly doesn't work as a stand-alone power increase absent engine mods to take advantage of it, and the only thing that makes it interesting is that it's a legal pump fuel under current rules. Outside of that, methanol will produce considerably better results, but of course, it fails the legality thing.

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it's not just legal in roadracing, they charge low or zero points for it, that's why it's gaining popularity

any engine mod, even a tune costs points and bumps you into the next class

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