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Old 29-07-2016, 14:21   #46
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Re: aviation gas for a 20hp yamaha

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Originally Posted by Myknjul View Post
Schooner Dog. Lee Airport in Edgewater has ethanol free fuel for around $5.50 a gallon. I have a 10HP Honda that just loves it. It's the only place I know of near Annapolis that has it.
Is that avgas or regular unleaded "pure" gas?
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Old 29-07-2016, 21:23   #47
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Re: aviation gas for a 20hp yamaha

Hello,
I liked Alfred E. Newman's explanation ( Artisanmach). I think ethanol gas will not hurt your engine if you use it quickly, storage allows it to absorb water. In Florida ethanol free gas is a couple bucks more than regular. On YouTube there is a video on how to remove the ethanol. Where have I gone wrong?
Good luck
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Old 29-07-2016, 21:55   #48
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Re: aviation gas for a 20hp yamaha

A quick test to know if your gas contains ethanol is the water test . Check on youtube.

91 usually doesnt contain ethanol. Ethanol is very bad for rubbers and seal of anything built prior to 2002. Ethanol is alcohol and will disolve lots of rubber parts with various issue in your fuel system. Avgas 100LL has a rated shelf life of 5 years but the lead will gum up valves and sparkplugs in any recent engine. But older engines will gladly gulp up a mix of 91 and 100LL and be very happy. Water does not mix with 100LL and 91 ethanol free it will condense and sink to the bottom so you can sump the water out.

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Old 29-07-2016, 22:49   #49
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Re: aviation gas for a 20hp yamaha

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Originally Posted by artisanmach View Post
More and more pilots are obtaining STCs for their aircraft to use autogas. Why? Because autogas is less expensive and the FAA has found no statistically significant safety-related issues with using autogas as long as the gasoline meets the octane requirements for your engine.
Partially correct....as usual the devil is in the details on this one.

The STC however specifies no ethanol in the auto gas because of water absorption and compatibility issues. It's also only applicable for 'lower' compression versions of a lot of the engines and none of the turbo'd engines as far as I recall.

As an aside, I do know two airplane engine rebuilders that claim they can tell almost immediately upon disassembly of an engine if it's been run any significant time on autogas based on the valves and seats. Neither of them recommend autogas in the slightest, but that's a matter for an aircraft forum.

We've used old fuel out of airplanes in old gasoline tractors, lawmmowers, and older cars without catalytic converters with no noticeable issues. (Even though it's much more stable than autogas, if the plane has sat for 6 months or so without full tanks, I tend to be pretty conservative and drain it and fill with fresh as a precaution.)

A64Pilot. I see in the thread that you're planning on leaving your plane to sit for a few years. Even though you've got a Continental which is less prone to camshaft corrosion, check out AeroShell's 'preservative' oil (AeroShell Fluid 2F) It's got additives that essentially leave a thin coating on all surfaces when the oil drains off them. Used it for a while on a plane that used to sit for 5-6 months over the winter.

Regards,
Mark
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Old 30-07-2016, 02:07   #50
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Re: aviation gas for a 20hp yamaha

vortex premium unleaded works well / av gas used to be 115 octane and needed firezone or castor oil additive for upper cylinder lube (too much lead)/ 100 octane sounds like normal super / modern 4 stroke outboards are designed to run on todays poor quality unleaded / we have trouble with our Yamaha 2 stroke running on opal fuel / it's to cold even mixed at 100-1 / opal is designed to stop petrol sniffing in alcohol banned areas / you have to do your homework cruising / you can't buy metho for metho stoves in those areas either/ premium unleaded for a few cents more per litre / leave the aircraft fuel for aircraft
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Old 30-07-2016, 07:10   #51
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Re: aviation gas for a 20hp yamaha

There are two Auto fuel STC's applicable to some small aircraft, Petersons and the EAAs. Last I looked anyway.
I have searched the NTSB database several time looking for an accident where ethanol fuel was a contributing factor and cannot find one, many, many people run it as they just don't check and Experimental aircraft of which there are thousands can run what they want.
Ethanol fuel isn't allowed, because it was not what the STC was issued for, no other reason, it may or may not work, cause harm or whatever, but it wasn't what the STCs were issued for, so you can't use it, that's all.


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Old 30-07-2016, 08:09   #52
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Re: aviation gas for a 20hp yamaha

[QUOTE=a64pilot;2178237]
I have searched the NTSB database several time looking for an accident where ethanol fuel was a contributing factor and cannot find one,

I find it hard to believe that I am one of few who have had a problem. I didn't crash and burn so maybe the NTSB doesn't know everything. Cheap car gas in a low wing plane left out in the sun on a hot day does not always work. I admit I didn't have the STC or check the quality of the fuel which must have been crap but I still almost crashed because of ethanol.
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Old 30-07-2016, 09:38   #53
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aviation gas for a 20hp yamaha

I don't doubt you, I expected to find several " engine failures" due to it, as you know by far the most common reason for an engine failure is fuel exhaustion, but I couldn't find any with ethanol or car gas being the reason.
Many way to search the database and I haven't for a few years, here is a link to it
http://www.ntsb.gov/_layouts/ntsb.aviation/index.aspx


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Old 30-07-2016, 16:28   #54
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Re: aviation gas for a 20hp yamaha

I use autogas, 89 octane, 10% ethanol in my 8 hsp, Yamaha 4 stroke. I use the additive Starbrite and have never had a fuel problem.
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Old 30-07-2016, 17:22   #55
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Re: aviation gas for a 20hp yamaha

I usually use the Marina gas which in Fl is ethanol free, but I have several times runs premium ethanol fuel, or maybe anyway, if you don't test, you don't know for sure.
But I'm cheating as my little outboard is fuel injected, meaning that from the time the fuel leaves the can, it's in a sealed environment, no air, no evaporation.
It is why I believe automobiles have no problems, and I believe the future for small engines too, my Husqvarna TE-450 dirt bike is fuel injected too, and it "carburates" brilliantly.

But in my lawn equipment which I have several 2 strokes, chain saw, edger, trimmer, weed eater, leaf blower etc. I use stab-bil religiously at higher than recommend ratio, and run out the carb every time, and even if the chain saw sits a year or two, I dump out the old, fill with fresh and it cranks right up, with ethanol fuel.




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Old 31-07-2016, 08:11   #56
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Wink Re: aviation gas for a 20hp yamaha

Lots of information, some speculation, and a few answers. Lets don't clutter up the thread with guesses! Unless you have DONE it, don't post it! Please!
I am lucky?? living in Georgia, lead and ethanol free gas is available at some stations, and is a better choice for small and/or engines that are not used a lot. It is legal here, the Feds only say that the "majority" of fuel sold has to contain ethanol. Pre-mix two strokes do not do at all well with ethanol, but all ethanol fuel starts to separate after a few months- and in some conditions sooner. Apparently, normal marine conditions of high heat and humidity don't work in our favor. Float bowls and needles can stick after only a week if any fuel containing ethanol is left in the carb. Often!
IMO, using av 100LL is not a good idea because of the potential lead issues, but the actual experience would depend on the duty cycle of your engine use, just as it does in aircraft engines. Used in higher compression aircraft engines that are run hard and hot, 100LL works fine, used lightly in engines that are mostly used to fetch $100 hamburgers, there will be lead build up that is NOT caused by detonation. The lead will contaminate the oil no matter how the engine is used.
I have found that the carb jetting on most small outboards built since 2005 regs took effect is excessively lean. It will work "on the bench", but in real life with less than ideal fuel, the engines are often hard to start and the idle jets are very easy to clog. I certainly would not suggest defeating/modifying your carb with drilled out jets as that would not be legal, but my Honda 15 starts and runs great
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Old 31-07-2016, 08:57   #57
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Re: aviation gas for a 20hp yamaha

[QUOTE=bruceb;2178887]Lots of information, some speculation, and a few answers. Lets don't clutter up the thread with guesses! Unless you have DONE it, don't post it!
.Used in higher compression aircraft engines that are run hard and hot, 100LL works fine, used lightly in engines that are mostly used to fetch $100 hamburgers, there will be lead build up that is NOT caused by detonation. The lead will contaminate the oil no matter how the engine is used.


So don't post stuff you don't know about either.
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Old 31-07-2016, 09:31   #58
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Re: aviation gas for a 20hp yamaha

Guy +1
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Old 31-07-2016, 09:38   #59
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Re: aviation gas for a 20hp yamaha


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Old 31-07-2016, 10:54   #60
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Re: aviation gas for a 20hp yamaha

Guy, sorry for any misunderstanding. I never ran any fuel with ethanol in my airplane, I did run automotive unleaded in one tank when I had an stc'd piper with an 0-320 low compression engine. I only used the auto gas for cruise, I did take offs and landings with the 100LL. I did much of my own service, and the plugs stayed a lot cleaner with the auto fuel. My later planes had higher compression and/or fuel injection and were limited to av gas.
I once did some engine service on an island where there were several larger aircraft "grounded" so the local residents were using the free fuel in their cars and generators. All of the engines were having serious issues with the lead after they had been run on av fuel for 50 to 200 hours, rings and valves were sticking, and the only cure was to rebuild them.
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