E85

[andyb]

I'm going to start with a disclaimer.  Ethanol in all forms is meant to be drank, the government is stealing food from the mouths of babies to make fuel, it's not efficent, etc etc etc.  So we don't need that end of this discussion in this thread.   


What's required to run a high-alcohol-content fuel?  Replace all the rubber bits with a compatable rubber, and rejet appropriately?

Rubber bits off the top of my head include the fuel lines, about 500 o-rings in the carbs, the rubber gasket on the filler cap, the seal under the petcock.  Missing anything there?  The fuel pump also would probably need to be swapped for an aftermarket one rated to use ethanol, and would have to be a little beefier than originally.

The reason why I'm bringing it up is that I've been hearing that while it's not efficent as a fuel (so your mpg is in the toilet), on a typical motorcycle engine with a comparatively high compression (as compared to say, a car), E85 has been shown to make pretty decent gains.  I raced with a ZX-10R yesterday who said he had around 188hp on pump gas on a dyno, but saw just shy of 200 on E85.  Obviously he's got an upgraded fuel system from stock, and I believe he's running mildly higher compression than stock (thin gasket, stock pistons; stock CR = 12.9:1). 

The theory here is that the alcohol's ability to suck more heat out of the intake charge (in part because there has to be more of it, y`know) cools the intake charge significantly as compared to gasoline, and if you can burn the resulting mix reasonably efficently, you get more power from the same engine, albeit at the cost of using more fuel.

I don't know of any E85 available locally, but I'm sure it's a matter of time.  I know that the more modern FI bikes are experimenting with it and seeing gains comparable to $20/gallon oxygenated fuels, but I haven't heard of anyone doing it on a carb'd bike yet.

Curious to see what the collective's experience is with it.  I understand that I'd have to measure the stuff I was getting periodically, as the actual ratio of gas:ethanol changes a fair bit.  If nothing else, knowing what requirements are to run E85 as far as reliability would be useful for 10-20% mixes as well.

[Pat Conlon]

Hey Andy, me thinks E85 is the future.
Depending on the season, most of us are now at the 10-15% blend. Like our taxes and our federal debt which will only go up, so will the percentage of ethanol blend only go up....If you think about it, it has to....

In my other life, I hang with a group of Miata junkies, many who have some form of forced induction (turbo or blower) on these little 1.8 liter motors. 200 rwhp is ho-hum common and 300rwhp is considered a common target goal. In a 2200 lb car it is quite fun.

Anyhoo....E85. yep, 2/3rd's the energy content as unleaded gas but a octane rating of ~108.

My Short answer to your question:
A definite advantage for a forced induction application, but for a normally aspirated motor the advantage is dubious.
Here is local guy (not me) who converted over to E85 to run in his coldside Eaton MP62 blown Miata. This particular setup does not have the common air to air intercooler to cool the intake charge, instead it has a 5th fuel injector which sprays fuel in the intake plenum to cool the charge. Also Larger fuel injectors and a longer spray time was needed due to the lower energy content but the octane advantage allowed him to run 3 to 4psi more boost without any problems of predetonation, common with 91 octane pump gas.
http://www.fastforwardsuperchargers.com/forum/showthread.php?t=2160
http://forum.miata.net/vb/showthread.php?t=409897&highlight=e85

Now, assuming you can/will convert the fuel systems and E85 becomes more widely accessible...
1) Would I run E85 in a fuel injected, turbo'ed street/strip bike? Sure, why not?
2) In a normally aspirated bike with carbs? No. A couple of reasons:
With fuel injection and a programmable ECU you can dial in exactly how much extra fuel you need, depending on load and rpm. With carbs, I dunno.....
Besides, on a normally aspirated motor, why would you need it? On a High Compression 14-1 motor for a track bike? Just run race gas, toluene or a can of octane booster.
Need the 108 octane for a high compression street bike? Get different pistons or a thicker head gasket...To take a street bike with a fuel tank which gives you a honest 200 mile range between fill ups, and reduce this range to 130 miles...naaaa, not worth 108 octane fuel.
Cheers lad!

[andyb]

I know that it works nicely in the boosted applications, because it's functionally high octane, so more timing and more pressure as well as the cooling benefit means more power.

And I'm right with you, I didn't think that it'd make power in a naturally aspirated machine.  And then I'm hearing about back to back tests comparing it and some of the race fuels like MRX01 and the E85 is doing pretty well!  What I'm unsure of is where the line is on compression that makes a difference.  The FJ is fairly low compression, but a street 600 runs up around 13:1, and a built-up trackday motor will go a bit higher still.  The only test that I've heard of the E85 doing well in involved pretty significantly more compression than an FJ would see.

I'm guessing my FJ will end up a little under 11:1, my other bike is spec'd at 11.5:1 (so probably lower in reality).

As for carbs versus FI, you'd need some dyno time to nail it either way, so long as the fuel gets vaporized well it should burn, ya?

If you could convert your carbs over so that E10 wouldn't hurt the rubber bits, that'd be great for a street driven machine, but if you could swap over the jets for a trackday (or have a set of spare carbs), the E85 is a lot, lot cheaper than normal race fuel.  I'm just wondering if there's gains that can be made without significantly higher compression.  On the street, the mileage hit is pretty severe and I wouldn't run it without building a motor specifically for it; I'd imagine that you could get away with higher compression even in an air-cooled application because of the increased cooling that the fuel allows.

I was just blown away by hearing of gains on a non-boosted application, really, and knowing that we're all going to end up burning some mix or another anyhow, wondered about taking the logical step and jumping ahead of the curve a bit.  Race gas is between $9 and $24 per gallon, if I can get E85 even at normal gasoline prices and see comparable gains on the track, why....

And yeah, I had a miata also (NA, C package without ABS).  Absolutely a laugh, especially on about 2" of fresh snow

[Pat Conlon]

....As for carbs versus FI, you'd need some dyno time to nail it either way, so long as the fuel gets vaporized well it should burn, ya?

That's what I'm not sure of...We know programmable fuel injection is ok but carbs....?
I don't know if the FJ's Mikuni BS36 CV carbs would be able to flow the additional 30%+ more fuel and still be effective.
Can you even get main jets, needles and pilot jets big enough to flow that much more fuel...if so, will it mix well in the 36mm throat?
Perhaps some 40mm Mikuni TMR carbs would be needed: http://shop.yoshimura-jp.com/en/product/syousai.php?id=1156
Or some Lectron's: http://store.valueweb.com/servlet/starrace/Detail?no=359
To take advantage of the 108 octane you should also have one of those new generation Dyna 2000 ignition modules where you can set a custom timing curve with your lap top computer.