Octane Factor in Saws

Ethanol laced fuel isn't too much of a problem unless it sits for quite awhile . Then it separates into 2 distinct layers and no way to recombine. Over time the ethanol tends to attack various parts of the fuel systems - sometimes directly others it is indirect. Being hydroscopic (absorbs moisture) it then causes oxidation of various components if it evaporates out of the system and tends to leave a film behind. 1-2 punch that plugs things up. Have truck sitting outside right now that the fuel system will have to be purged.

 

I run 89 Octane E Free rec fuel in my saws. Little Stabil & Seafoam along with it. Mix 5 gallons at a time & no issues. Ethanol I don't care for, octane rating I don't worry too much.

 

I run 87 E-free most of the time....however...the last i got 2.5....i filled it with 91 E-free.....3.80 a gallon.
Didnt get a chance to run any saws on it...this weekend..

 

Any marinas or boat sales in your area? They generally carry ethanol-free fuel. I'm lucky there is a marina about a half mile from my house. They stop selling fuel at the end of October so after that I have to drive several miles to a tool rental company that sells 91 octain clean fuel. There is a website that lists places in each state that sell clean gas, Ethanol-free gas stations in the U.S. and Canada

 

I would run ethanol gas premium if I knew I was going to be cutting a lot. But that was before we had e free pumps close to me. I used to run premium with ethanol and id finish up with true fuel canisters. But now i have a 93 octane e free option close to me so that's all I use

 

Thanks Ralphie for the link. Looks like there are at least 3 places within a 30 mile radius. I will have to check them out.

 

5 gallons with stabilizer may last long enough to make the trip worthwhile. Good luck!

 

Mdavlee ran the numbers on some ported saws a few years ago, he came up around 8:1-8.5:1 compression ratios on them iircc. My saws run better on 87 octane but it has ethanol so I run 91 rec fuel which is e free, I should add that I have both ported and stock saws.

 

That's interesting, I've never heard that one before. Is that static or dynamic C/R.

Mmmmm lead vapor baby! Just like the good oldays! I know" LL"...

Shelf life is relative. The biggest thing is Gas looses octane over time. Old gas will burn....it will knock clack and smell awful.....I've run some really old stuff before in small engines
E free turns to gunk, plugs and gums everything up varnishes everything, flakes off through the carb etc....
In contrast..
I recently started my e85 car that's sat for a few years, it fired right up. Ran like you just parked it.

 

A few things I've learned from almost 40 years of 2 cycle kart racing. Storing large quantities mixed should be discouraged. Store unmixed fuel in a metal container and mix in smaller amounts as used. Plastic containers on a concrete floor is a no- no, it will draw moisture.
I did some dyno testing on high octane racing gas in a low compression class engine. To my surprise 108 octane gave a better result than 93, I'm not sure why but the only explanation I could come up with is the higher octane slows the burn time and retards the timing but the rules limit a minimum and maximum timing. Less timing helps these restrictive engines and I think slowing down the burn effectively retards the timing.

 

Should have told em you had a paraglider

 

Ditto plastic is not a moisture barrier!

108..VP? Race gas has numerous variations, from true oxygenationt to other energy boosters. It really is different than pump.
Two stroke oil supposedly slows the flame front as well Wich adds in to your information.
A wild guess would be an incomplete burn.
In my experience theroetical max timing for power is usually pretty close and should be targeted, over timing loses torque wich hp is derived from.

 

Actually, most even semi recent saws , if not all are designed to run on e10 87 octane. Now if it's older, or modded, you might want to run e free and higher octane. My 18-19 yr old stihl 029s even says to use e10 87 octane. It's on the original top end and up until last year it was used constantly, and in SE wisconsin, we've had only reformulated gas for over 20 years.

 

I will again point out that just because they advertise e free gas, that it doesn't need mean that it actually is ethanol free. If the tanker shows up, and it's got e10, they have to take it.

Just keep that in mind.