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25% Ethanol tuning

  • Thread starter Thread starter waterman
  • Start date Start date
W

waterman

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Guys this is a plea for assistance, hopefully someone here has experience with ethanol and can lend some expertise.

Chris (Shirazdrum) had holed his basically stock 850 on his journey across South America. Members have shipped a replacement motor and concern was brought up why did first engine fail. One question was the quality of fuel, specifically, how much ethanol. A quick search of Wikipedia shows that Brazil requires 25% ethanol in their gas and most of their cars are flex fuel designed to work with this and higher ratios.

My question is how best to tune for 25% ethanol? Can one simply dial up the jetting to compensate and if so any guesses on how much. Some cursory googling suggested somewhere in the neighborhood of 30% increase for E15 which is only 15%.

Likewise, they talk of the need to advance timing, can this be changed with the stock components? Again, how much will suffice?

I hope I am only over reacting to this discovery, I would just hate to hear that all of the time and effort spent to deliver motor resulted in another engine failure.

Here is his original thread,

http://www.thegsresources.com/_forum/showpost.php?p=1344905&postcount=443
 
No direct experience with Ethanol - but years of running Methanol blends...which present the same problems.

First - timing - I wouldn't change it. reason, more advance equals more heat, and with an air cooled motor in a hot climate, well,no.....

Jetting - yes, at 25% I'd think a general richen up should suffice. set the idle in the usual fashion looking for fastest idle then close the air screws slightly to ensure a safely rich idle. I'd shim the needle or raise it if they're adjustable till response is OK.
Mains - according to my book std is 115 - I'd go to 140 initially and keep an eye on plug colour. Most of this sort of touring is done on the needle anyway.
Plugs - std is B8ES I see - this should be cold enough.
Expect it to be a little sluggish until warm - and the mileage won't be pretty either.
If the ethanol starts dissolving fuel hoses to the point where the bowls start getting dirty, be aware that a blockage will melt another piston very quickly.

Good luck
 
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I have a customer that flys his Bonanza into Bolivia to do missionary work. He said the same thing about the fuel. Lotsa alcohol. The Bonanza has a basic air cooled 6 cyl 470 CI engine. Ill have to contact him to see how he deals with it.....
 
You guys are great, Chris doesnt get online very long or often so to maximize the likelihood of the findings it would help to repost it on the main thread linked above.
 
Bonanzadave, also ask him about the ethanol content of 100LL or any other type avgas.
 
rustybronco said:
Bonanzadave, also ask him about the ethanol content of 100LL or any other type avgas.
Click to expand...

According to this wikipedia article, the FAA prohibits the use of ethanol in av gas. I don't know if this matters, since other countries may not follow FAA guidelines. Likewise, it doesn't say it is prohibited in all av gas blends.

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

Even still, this may be the best alternative since the quality of avgas may be more tightly regulated. Not sure what tuning changes he would have to do for avgas if any. The lead certainly wouldn't hurt our motors.
 
If avgas doesn't work out, how about some adjustable jetting devices? Back when I was playing with my KLX, I had read about Dial a Jet. I see you can buy a kit for around $240 that fits a 750 and 1100 so it most likely would work with an 850. Does anyone have experience with this or a similar product?

http://www.thunderproducts.com/dial_a_jet.htm
 
Skateguy50 said:
Its worth a call... I can give them a ring and see first what they think and second if they will offer up a kit for some real world testing and exposure.

If I read the chart here:

http://members.dslextreme.com/users/bikecliff/images/carbspec_float_height.html

correct, it looks like the 750 and 850 have the same carb but stock setting with a smaller jet size.
Click to expand...
If you're referring to the Dial-A-Jet I doubt they will offer a kit for free. These have been around since at least the early '80s so I doubt they need either the testing or exposure.
 
Well they might not need either, but it never hurts to ask... that is half the point of being a non profit. Z1 enterprises didnt need any extra exposure from this crowd but they stepped up to help out.
 
GregT said:
Jetting - yes, at 25% I'd think a general richen up should suffice. set the idle in the usual fashion looking for fastest idle then close the air screws slightly to ensure a safely rich idle. I'd shim the needle or raise it if they're adjustable till response is OK.
Mains - according to my book std is 115 - I'd go to 140 initially and keep an eye on plug colour.
Click to expand...
http://www.enertechlabs.com/fuel_phase_separation_in_ethanol.php

Ethanol has a rating of 76,000 Btu's per gallon. gasoline is somewhere between 109,000 and 119,000 Btu's per gallon. using 114,000 Btu's as the average for gasoline and a 25% blend of ethanol with gasoline, I calculate a 10% increase in fuel needed.

IF I calculated correctly, then I would suggest trying 127.5's and raising the needle one 'effective' clip position.
 
The info I have quotes 410 BTU/lb for ethanol and 140 BTU/lb for petrol

Phil Irving quotes 25% jet flow increase required for 20% Ethanol in Petrol/Benzol which is a close approximation of a modern 25% Ethanol brew,
and experience has shown that his figures are a very good starting point.

Starting from 115 this would give approx 130 mains....I'll stand by my first stab - 140 as high ethanol mixtures can be run rich without worry.
The real area where it should be rich is on the needle as this is where most real world running is done - and for long periods too
 
get a E.G.T. gauge and quit guessing

is a BTU unit in metric? so does one convert pounds of gas or kilograms of gas ? and then divide by exactly what mathmatic constant in relation to alcohol content / O2 density, altitude, Humidity?
 
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