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aviation gas v. high octane no ethanol

Started by ksks, October 30, 2013, 05:56:41 PM

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ksks

Is there any benefit to use aviation gas over premium no ethanol in the 2cycle motors?
Striving to be average!

ladylake

 Not unless it's highly modified with really high compression, the lower octane will make more power as it burns faster.   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

Joe Kidd

Plus there is a small amount of lead(100LL) in the exhaust which can't be good long term. Like the previous post, after about 95 octane there is a slight decrease in power in a non modified saw.
Husq 545
Husq 562XP
Jred 2188

ksks

Interesting...

What about difference in shelf life?
Striving to be average!

Joe Kidd

100LL is made to higher purity standards, so I'd say it's shelf life is superior. I don't have access to any, but would like to give it a test run for the heck of it.
Husq 545
Husq 562XP
Jred 2188

LaegersATC500R

Why are you considering aviation fuel? What are you up to??
Morton Downey Jr. was a good man.

lone wolf

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gologit

I've been running 100LL av-gas in my saws for several years.  I don't see any real problems with it.  I cut anywhere from sea level to 7000 ft. and if there's any loss of power due to the gas it's not enough to notice.
You might have to retune your carb a little...some guys do and some guys don't.

The thing I like best about av-gas is that it's refined to strict standards and a gallon bought in California will be the same as a gallon bought in Maine.  You can count on av-gas clean and pure.  If you're buying it from the local airport it's filtered and water checked before it ever hits the pump.

Car gas, especially where I live, is always a crap-shoot for quality.  The little mom and pop mini-markets buy gas from brokers and you never really know what's going in the tank. 
With av-gas you know what you're getting.
Semi-retired...life is good.

Joe Kidd

Husq 545
Husq 562XP
Jred 2188

mad murdock

Av-gas will not varnish even if left sitting for more than a year. As an aircraft mechanic by trade, (27yrs +), it is good fuel. There has been a big push for it to be replaced by 2015, but that date has already been changed (pushed back).  It is hard to find a viable substitute, that works as well.  If you are going to use it in extreme cold, it does not atomize as well as lower octane fuels in -10 below or colder.  If you don't plan in using a saw in subzero temps, go fer it. You may experience minor lead fouling on the spark plug, but with regular plug changes, it is not a problem.
Turbosawmill M6 (now M8) Warrior Ultra liteweight, Granberg Alaskan III, lots of saws-gas powered and human powered :D

Windy_Acres

Quote from: ladylake on October 30, 2013, 06:04:16 PM
Not unless it's highly modified with really high compression, the lower octane will make more power as it burns faster.   Steve

Just curious, did you read this somewhere, or have you tried it first hand. Ive had exactly the opposite results running 102 octane in 2 strokes. They scream with power, and the power is clean, and you get more and faster rpm's under load.

Ive not tried it in a saw, but 2 stroke "power sports" LOVE the stuff. Next trip to town, Im going to bring some home and give it a try in 3 different brand saws and see if I can tell a difference. The only thing I would expect is harder starting cold.

Joe Kidd

I'll just add at least in saws that's the case. If AS was up I could provide some links on dyno tested saws using high octane fuels. Cheers
Husq 545
Husq 562XP
Jred 2188

acrosteve

Different that av gas, but I have heard that "race fuel" will not gell in a carb when left sit for long periods.  There is a station around me that sells it, but I have never felt the need.
Timberking B-20

Windy_Acres

Quote from: Joe Kidd on October 30, 2013, 07:21:49 PM
I'll just add at least in saws that's the case. If AS was up I could provide some links on dyno tested saws using high octane fuels. Cheers

Ok, interesting, I wonder what is different about a chainsaw 2 stroke, than the rest.... Im still going to give it the test for myself. That or Av gas is the only thing around here, I know I can find that is not blended.

Joe Kidd

Quote from: Windy_Acres on October 30, 2013, 08:19:41 PM
Quote from: Joe Kidd on October 30, 2013, 07:21:49 PM
I'll just add at least in saws that's the case. If AS was up I could provide some links on dyno tested saws using high octane fuels. Cheers

Ok, interesting, I wonder what is different about a chainsaw 2 stroke, than the rest..
Not sure. Let us know your results.
Husq 545
Husq 562XP
Jred 2188

AdkStihl

AV gas burns rich and slow, so carburetors need to be tuned accordingly.
Contrary to many persons beliefs, AV gas (or any higher octane fuel) burns cooler and makes less horsepower....it just burns LONGER.
Race engines whether in a car or in a saw have much higher compression. Compression makes horsepower and with it comes heat. More compression - more heat. Higher compression engines need higher octane to prevent pre-ignition -higher octane fuel is resistant to detonation (pre-ignition).
Running pump gas in a high compression engine can be detrimental.
Although I doubt you'll blow any work saw sky high by running 87oct.
I've heard of saws with 220psi + that run on 87oct with no problems.
Running high octane (100oct +) in normal engines doenst really do jack crap except burn cleaner.
If anything....youre decreasing engine output.

A gentlemen I know on another forum recently built a chainsaw dyno. One of the tests was octane.....100oct VS 92oct.
In 2 out 3 different tests, the 92 octane generated more HP than the 100 octane.
The biggest gains were had by advancing the ingnition timing by 6 degrees.
J.Miller Photography

AdkStihl

Quote from: Windy_Acres on October 30, 2013, 07:13:18 PM
Quote from: ladylake on October 30, 2013, 06:04:16 PM
Not unless it's highly modified with really high compression, the lower octane will make more power as it burns faster.   Steve

Just curious, did you read this somewhere, or have you tried it first hand. Ive had exactly the opposite results running 102 octane in 2 strokes. They scream with power, and the power is clean, and you get more and faster rpm's under load.

Ive not tried it in a saw, but 2 stroke "power sports" LOVE the stuff. Next trip to town, Im going to bring some home and give it a try in 3 different brand saws and see if I can tell a difference. The only thing I would expect is harder starting cold.

You should read a little more and perhaps try some in your saw or OPE.
You will notice a few things...cleaner burn, smoother running, lower operating temps, nice aroma.....but higher performance is not one of them.
J.Miller Photography

LaegersATC500R

I will give AV a try. There's a small airport not to far from me. I'll pick up 5 gallons. Right now I use 92 octane and use an additive to counteract the effects of ethanol in the fuel. It's hard to say but the saws SEEM to run a bit better during  acceleration.
Morton Downey Jr. was a good man.

ladylake

 I'm lucky here as I can get 91 octane without ethanol at 2 stations 2 miles away.    Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

RCBS

I finally found a non-ethanol source this summer.  90 octane with no corn.  It's a twenty mile ride and is slightly more expensive, but the peace of mind is worth it.  Especially after seeing hundreds of fuel related issues working in a repair shop for a few years.  This was mostly on generators and pumps.  Not always old gas, but dirt and water as well.  Many people never look in their gas cans/tanks and just assume that since there is fuel present, that it should run. 

I have a coworker who uses AVgas and has good results with it, but he pays more than I do for the non ethanol blend regular gas.

I use corngas in my truck as it is not practical to drive 20 miles to fill up, but I would for sure pay a premium to have pure gas available at all stations.  The truck gets an average of 2mpg better on pure gas.  Why are we not given a choice of fuels?  I'm tired of corn being rammed down our throats.  Read some ingredient labels and you'll see that literally its being crammed down our throats as corn syrup.  Somehow it has become a mainstay ingredient in *everything!

/rant.
Echo CS-3400, 550xp, Jonsered 2166, L3130 Kubota, '78 JD 300 backhoe, Kubota RTV900, JD2305, lots of sharp stuff and several firearms

ksks

Good read.  I do use non ethanol premium in my small engines.

Problem is the gas will sit up to a few months. 

Stilh has its own gas mixture.  Its really expensive, but suppose to last a year.  Just trying to figure how to protect engines that don't get used regularly.  I do add Stabil or Seafoam.  Sounds like that may be the best option father than monkeying with the carb when I don't know what I'm doing.

Thanks for the info.  Very helpful.

ksks
Striving to be average!

john_bud

There is a lot of "marketing" in peoples minds about high octane.  Too much madison avenue and not enough MIT in the mix!


For 2 cycle engines power is lost because there is not enough time to fully evaporate the fuel before ignition AND there is not enough time to complete the burn before the exhaust port is uncovered.   The still liquid portion of the fuel is exhausted partially unburned so there is lost power.  Same as opening the exhaust while still burning the fuel. Lower octane evaporates faster and burns faster, so there is less if those losses.  You dont see this in cars as the rpms for normals highway speeds are much less than a saw's idle.

Just my $0.02

280 acres of tree farm

nmurph

I have run E10 in all my saws, all of which are modded, some with pretty stout compression, for several years without a problem...much is made of ethanol based on anectdotal evidence. Keep the fuel less than 3 months, use a good quality synthetic oil with a stabilizer, and you won't have a problem. AV gas has a long shelf life, but unless you are running compressions north of 220, the extra detonation resistance is not needed and does lessen performance.

labdad

Quote from: RCBS on October 31, 2013, 06:19:38 AM
I finally found a non-ethanol source this summer.  90 octane with no corn.  It's a twenty mile ride and is slightly more expensive, but the peace of mind is worth it.  Especially after seeing hundreds of fuel related issues working in a repair shop for a few years.  This was mostly on generators and pumps.  Not always old gas, but dirt and water as well.  Many people never look in their gas cans/tanks and just assume that since there is fuel present, that it should run. 

I have a coworker who uses AVgas and has good results with it, but he pays more than I do for the non ethanol blend regular gas.

I use corngas in my truck as it is not practical to drive 20 miles to fill up, but I would for sure pay a premium to have pure gas available at all stations.  The truck gets an average of 2mpg better on pure gas.  Why are we not given a choice of fuels?  I'm tired of corn being rammed down our throats.  Read some ingredient labels and you'll see that literally its being crammed down our throats as corn syrup.  Somehow it has become a mainstay ingredient in *everything!

/rant.

What he said 8)
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Extraordinary men have solutions

nmurph


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