110 octane racing gas in a work saw... What's your thoughts?

[blsnelling]

Even if static compression isn't high, dynamic compression is higher on a saw with a pipe. How much? I have no idea. You may or may not need higher octane fuel. I don't have the answers for you. Not many here with experience with pipes. Hopefully someone will come along that does.

 

[Rusty-880]

IF Im correct in my reasoning that a pipe will give comp on a full stroke instead of from exh closing I will have dynamic comp of around 13:1.
I picked up a 075 (i think) that had scored the piston. Freed the rings and smoothed it all out with wet n dry. Maybe I should find a fuel tank/starter and experiment with the limits....

 

[MtnHermit]

Waste of your money unless you're experiencing pre-ignition (pinging). Thermodynamically there is no advantage to more octane.

 

[rupedoggy]

Found this thread after talking to one of the guys at local stihl shop about av gas. I am in the middle of building an expansion chamber for my worksaw 880 and think ill need higher octane to prevent detonation due to high cylinder pressures when it comes on the pipe. He told me that av gas will cause the saw to run really hot, probly seize, if I could run saw at 10k and flywheel at 20k it might be ok with av gas.
Is there any high oxtane fuels to stay away from for this reason? Highest octane I can get at servo is 98 (94US I think). I was thinking of running 50:50 mix of 98 and av gas. Any thoughts either way?

I am sure your dealer is a good Stihl man and business man but he is totally wrong about higher octane running hotter. It is just the opposite. Mike

 

[pops21]

89 with ethnol is fine by me. Its stored in a air tight container. Durning the summer the can swells. So I know its air tight. After one month the rest gets put in either my wifes car or mine. I also only make two and a half gallons at a time.

 

[FlyLow]

I am sure your dealer is a good Stihl man and business man but he is totally wrong about higher octane running hotter. It is just the opposite. Mike

+1


110 allows to run a little leaner too.

 

[Rusty-880]

I am sure your dealer is a good Stihl man and business man but he is totally wrong about higher octane running hotter. It is just the opposite. Mike

Thats what I figured. Being leaded it should lube it a little nicer than pump fuel too.

 

[Rusty-880]

Waste of your money unless you're experiencing pre-ignition (pinging). Thermodynamically there is no advantage to more octane.

Thats my main reason for looking at higher octane. With the pipe it should be running fairly high comp in the cut at full load. Wanted to make sure I have combo right before it goes in wood and gives trouble.
Piston top has been sanded smooth and will be polished before assembly, works in 4 strokes to prevent detonation... Would do head too but kinda hard to get to.
I should be fine without any of that and running 98 (94) but cant hurt to go a little extra while its apart

 

[WeenerDog]

Don't wanna thread-jack, but this reminds me that when I picked up my new MS290 a couple of years ago, the guy (owner of mom/pop retail / repair shop) told me Stihl demands mid-grade gas only; no regular, no super. I think he said (hinted?) that it could void the warranty. Around here, mid-grade is 89, super is 91. So, I dutifully run mid-grade. Is this a bunch of horse puckey?

 

[Rusty-880]

Well, the 880 owners manual says
"use only high-quality brand-name gasoline with a minimum octane rating of 90 - leaded or unleaded"
Unleaded only to be used with catalytic convertor.

My 880 was bout new in june 2009. All working life has been on a mill cutting ironbarks, bloodwoods ect, very hard work. I usualy ran 91 AUS, sometimes 95. No trouble came from the fuel

 

[limited edition]

Warning in US owners manual:
View attachment 222294

Warning in Canadian owners manual:
View attachment 222295


As living North of the border in a Province that does not add Ethanol to high octane fuel, my Stihl dealer strongly recommended using high octane only, as it contains no Ethanol.

 

[Jeff Lary]

I use a lot of 100 LL Aviation gas at about $4 per gallon, I have experience no noticeable performance issues, not saying its better or worse in the performance, but the real benefit is the Aviation gas last so long, and I have had zero fuel related problems in either daily used saws or saws that have sat for upwards of 2.5 years with it in and then were finally started, again 2.5 years later and they started and ran great.

Sam

I was in a saw shop the other day and told the guy I had a few saws.I told him they were not running everyday and he told me to buy av gas because it has a supposedly 5 year shelf life. In my saws that will not get run regularly should i buy some of this and run some into each saw? Right now i have pump gas w/ stabil in each tank but ,....Would I be better off buying the av gas and go that route?(They may sit a few years between running ,just an in case they do sit that long I guess)

 

[Arrowhead]

I was in a saw shop the other day and told the guy I had a few saws.I told him they were not running everyday and he told me to buy av gas because it has a supposedly 5 year shelf life. In my saws that will not get run regularly should i buy some of this and run some into each saw? Right now i have pump gas w/ stabil in each tank but ,....Would I be better off buying the av gas and go that route?(They may sit a few years between running ,just an in case they do sit that long I guess)

I won't run regular pump gas if it's more than 2 months old. I would HIGHLY RECOMMEND the AV gas if your leaving it in the tank a year. The massive amounts of ethanol there putting in pump gas will eat your saw over time.

 

[Slamm]

I was in a saw shop the other day and told the guy I had a few saws.I told him they were not running everyday and he told me to buy av gas because it has a supposedly 5 year shelf life. In my saws that will not get run regularly should i buy some of this and run some into each saw? Right now i have pump gas w/ stabil in each tank but ,....Would I be better off buying the av gas and go that route?(They may sit a few years between running ,just an in case they do sit that long I guess)

Yes, get the AV gas for sure for that situation. As it will not hurt your saw. I'm in the same situation with a couple of saws that see little use from time to time. I don't want to waste my time and fuel and rubber parts, pouring old auto gas out, because it will either varnish the insides of the carb and gum everything up or it will eat the rubber parts with ethanol, either way its a bad and expensive deal, to deal with. I'm not sure about these problems others have had with AV gas, I've sure never had any issue with it except the added expense, but they didn't burn up a saw or ruin parts of the saw or waste gas pouring it out due to age, which is all more expensive than $5 per gallon gas.

Sam

 

[Terry Syd]

These octane threads are repititious of people saying what they run. OK, that's what they run, yadda, yadda - here's a question/post I've been waiting to see to put this all to rest -

Has anyone ever had a saw blow up because they ran low octane fuel? Say 87 octane regular fuel in a stock saw.

Forget the ethanol argument, we all know about that - just deal with the low octane issue. You know, seizure because the saw went into detonation because of low octane (not a lean mixture issue, but an octane issue).

Anyone?

 

[rupedoggy]

Yes I posted a picture on here years ago of a saw piston. That piston suffered death by detonation. IIRC it was a 272 piston. I took all my old aluminum to the scrapper so can't repost.
Look at it this way. The gas starts out 89. You add a little mix and it goes down. It sits around a little and the light stuff evaporates off and it goes down more. How low do you want a saw to run? Most of you guys spend more on keeping the saw super clean than you would on the good fuel. Why not run good stuff on the inside too? Mike