Tuning for ethanol

I've been searching for tuning articles on ethanol - a concise explanation on the impact of ethanol in fuel - there doesn't seem to be much available that's consistent.

I've seen the amount of ethanol in fuel can vary from batch to batch - and most of the mixing is done at the local level - not at the refineries... so 10% may actually be 11% or 12%...

It's clear you have to rejet, but how much?
And should you change ignition timing any?

The people on the car forums can't agree on very much... ...and that's including some professional performance tuners.

In regard to ignition timing, I've seen retard it, leave it alone and advance the timing... that about covers all the possibilities doesn't it...

In regard to rejetting, I've seen leave alone or rejet as much as +10%. I've seen leave alone the idle circuits, and just rejet the top-end...

In regards to how fast the fuel burns, I've seen slower and faster.... hmm...

What are the facts? If anyone has a link to any good (proven) articles, please post them.

BTU's - ethanol produces about 30% less BTU's than pump gasoline. So when blended at 10% with gasoline, that's dropping the BTU's by 3%, or 4.5% at 15% mix. Does that mean you have to rejet 1-2 main jet sizes to compensate?

With my stock Z1A, it does seem to want more main jet. I'm going to try upping the main jet at least 2 sizes to see how that performs. I may end up raising the needle a little as well.

This is a pretty basic article with the info for recommendations, 10% advertised blend.

"E10 in Small Engines
Small engine manufacturers allow the use of E10, and small engine owners with questions about E10 compatibility should consult their owner’s manuals or contact the engine manufacturer to identify any potential issues. Issues that have been identified thus far generally relate to pre-1980 models of boats, motorcycles, snowmobiles, ATVs, lawn and garden equipment, etc. For instance, certain types of rubber used in seals and hoses may deteriorate more rapidly when exposed to ethanol-blended gasoline. There have also been reports that gasoline containing ethanol may cause problems for boats manufactured in the mid-1980s and earlier with fiberglass gas tanks. The resin used in these tanks may be attacked by the ethanol, resulting in ignition problems and even tank failures. Owners of these boats should contact the boat manufacturer.
As for snowmobiles, some manufacturers recommend that, when using E10 gasoline, the carburetor main jet be one size larger than the main jet required for regular unleaded gasoline. For example, if a 400 main jet is recommended for regular unleaded gasoline, a 410 main jet must be installed if using an oxygenated gasoline like E10. The owner’s manual will contain specific manufacturer recommendations.
In general, E10 has a greater affinity for water than conventional gasoline, and this may aggravate water and moisture problems in particular fuel storage or unused engine situations. If a problem already exists, then ethanol may make it worse. However, the manufacturer recommendations for storing fuel (either outside the gasoline tank attached to the engine or in it) are the same regardless of whether one is using conventional gasoline or E10. These include:

Mixing only what’s needed for two-cycle gasoline and oil mixtures;

Not storing gasoline for more than 30 days unless a stabilizer (available at most hardware and small engine repair shops) has been added. When purchasing a fuel stabilizer it is important to ensure the stabilizer is compatible for use in gasoline containing ethanol (label may say gasohol); and

Running the engine dry at the end of the season. (Note that unmixed “old” gas can be burned in your car by adding one part old fuel with five parts new fuel"

I can attest to the shelf life of ethanol fuel being very short. It's changed how I store the bikes over the winter. I used to fill the fuel tanks and put stabil in the tanks, but now I totally drain the fuel system. I still have to leave fuel in some vehicles (like my kawasaki v-twin engined garden tractor), I use stabil in that and also run seafoam to help keep them ungummed...

With my E10 consuming '87 GSXR 750, I had a substantial midrange bog, and a top end break up, all attributed to what felt like a lean out. My GSXR was completely stock, as was factory jetting. Long story short, two main jet sizes richer, one size richer pilot, and a shim under the needle has got my 750 running perfect now !

I also added a 1K ohm resistor in my GPZ's air temp circut to richen the DFI fuel curve as well. Again excellent results after the mod. This is espacially important where I ride my bikes in cold 40-50F temps .

Ethanol will make you run leaner, so increasing the jet size would be required if you notice issues.

The added ethanol also makes the fuel more resistant to detonation. However, it does add the water in fuel issue as stated, and lowers your fuel mileage.

I wouldn't bother messing with the timing. Technically you may be able to advance it more without detonation, but without a dyno you have no way to know if you a gaining or losing power by doing so.

Jeff.Saunders wrote: BTU's - ethanol produces about 30% less BTU's than pump gasoline. So when blended at 10% with gasoline, that's dropping the BTU's by 3%, or 4.5% at 15% mix. Does that mean you have to rejet 1-2 main jet sizes to compensate?

I am not an expert either, but I don't think "riching up" compensates for lower energy density. Ethanol is just a crappier fuel than pure gas. But, the optimium air-fuel ratio is what it is, forcing a richer mix may not give more power. I think you just live with the reduced performance and fuel mileage. At least, that's what we have to do here.

Not true.

It works the same as switching over to 100% alcohol in a race vehicle, just in a much smaller scale.
You must increase the amount of fuel the engine receives, for it to run to it's full potential.

Look at jet sizes in 100% alcohol carbs. They are huge.

You do, however, have to live with reduced fuel mileage and susceptibility to water contamination. It also causes issues with some rubbers and gaskets.

+1 on the winterizing, i got caught up in my build and didnt run all the gas out of my other bike, it left a greenish jelly in the bottom of the float bowl, I had to completely clean the fuel system :angry:but Jeff it was a v twin engine so i now run mine dry, why do u say u have to leave a little fuel in them ???

I don't know why anybody would run ethanol gas unless forced to like we are. Aside from poor performance and mileage, it already ate the guts out of the fuel pressure regulator on my Chevy.

bountyhunter wrote: I don't know why anybody would run ethanol gas unless forced to like we are. Aside from poor performance and mileage, it already ate the guts out of the fuel pressure regulator on my Chevy.

In our area, there's not much choice without finding an airport or marina with straight gasoline.

Reading more and more on the subject, E85 ethanol is considered a more potent fuel - the issue is getting the full benefit - and battling the negative side effects - rubber issues, gumming up carbs.

Part of my desire to learn more is our cusotmers are starting to battle this issue more and more. So the more we know about turning for E85, the better.

My hunch is there's not really uniformity in the alcohol mixing, based on personal experience.

I get feedback from guys all over the country from engines I've built and heads I've ported. What I see uniformly is a trend to need to richen up the mixture considerably in the midrange in order to get the plug to color up and the throttle response crisp.

Where main jet is concerned, to notice a considerable difference, IMO, you'd have to have been on the fringe of lean to begin with if you have a considerable dead spot on top.

As far as storage....last winter I filled the tank and it sat for 6 months untouched. This spring, it fired right up...not a hint of a problem.

I also got a recall on a new Husky trimmer I bought last summer that is related to the alcohol problem with gasoline. They want to install a new gas cap because the caps start leaking and may cause a fire :ohmy:

The more alcohol they put in the fuel, the worse it's going to get.

Would be interested to know how you make out with the KZ Jeff

here is a link I posted before
pure-gas.org/
thing is no one knows for sure about who and who doesnt carry non ethanol gas
call the distributor
I have researched this in depth and Larry u r proly right about inconsistencies, but u never know, u said 6 months, do u know if urs was e gas or non e gas ???/
i let my chopper sit for about 2 to 3 months with only and occasional quickie start, BAD MOVE after a spring test run of about 50 ft ( it stalled completely out) a disassembly of my almost new S & S carb revealed a host of green goo in the carb bowl, it had gummed up the accel pump and was a complete mess, ait took 2 through cleanings to get it,
I keep a special gas container for my bike tunings and such that i KNOW is completely clean, (i had issues with crap in my carb) not long ago I didnt use it for about a month and there was just a touch of gas left in it, I was cleaning a mower carb and poured some into a container and noticed a definite green tint to it, and it seemed to have a slightly increase shall we say thickness to it,, I HAD SEEN THAT BEFORE. Its a definite issue.
NOW like Mr Saunders said what and how do we tune for it??? Well this is my dilemma, I have two pure gas stations within 20 miles of my place. If u will notice on the link there are quite a few but who knows for sure how many more. I see almost none in the north. I (and many others) will have to decide which route to take, tune for e gas or hunt non e stations, prolly the latter :pinch:
here's a side note on corrosion, My carb on the chopper was almost new, the goddamned ethanol corroded the finish off the inside of the bowl, the float needle, float clip and pin, , its not causing and issue at this point but I'm expecting futur trouble
Fortunately i learned this lesson before i finished my Z1, it would have been a bitch to clean all four carbs instead of one, as far as jetting goes, I havent had to change anything yet, but i did have to lean out slightly on one carb, otherwise she's runnin like a champ