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Octane Factor in Saws

Discussion in 'Chainsaws and Power Equipment' started by Marshel54, Nov 13, 2018.

  1. Marshel54

    Marshel54

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    Can you tell the difference in saw performance with a higher octane fuel?
    I have been running the 87 octane fuel in my saws because that is the only octane available in the Podunk town closest to me.
    I was having saw problems a couple of weeks ago and went to the Stihl Toy Store and bought a tune up kit. I also bought their $8 per quart pre mixed fuel. Can't afford to use this all the time.Figured that I will leave no stone unturned. Boy that saw ran like a raped ape. No comparison to before. Don't know if it was the fuel or tune up kit.
    I was looking at the can of fuel and it said 93 octane. I mixed up a gallon of 91 octane fuel and haven't had a chance to run it yet. Was it the increased octane or do they put a power boasting additive in it?
    If it was the fuel, I can't wait to get it in the ported saw. Should make firewood with out starting it.:D

    Edited: 91 octane on my mix not 93
     
    Last edited: Nov 13, 2018
  2. JB Sawman

    JB Sawman

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    Never run 87 octane fuel in saws most manufacturers require 89 jonsered requires 91 all the canned fuel is ethanol free and 91to94 octane the saws run and start better on the canned fuel but at least always run premium in 2 cycles its worth the extra money but remember if the fuel has ethanol it has to be used in 30 to 45 days because it starts to go bad by absorbing to much water from the air I have never seen so many lean seizures as I have in the last 8 years the new saws run so lean and high rpm they don't tolerate bad fuel I use canned fuel in my saws for years now and have had no problems it is expensive but I run many classic homelites and parts are hard to find I also have a woods ported 395 and I wont risk putting pump gas in it to me the extra money is worth it
    JB:saw:
     
  3. JB Sawman

    JB Sawman

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    Hey Marshel54 forgot to add a lot of napa auto parts carry SEF small engine fuel @60.00 for 5 gallons and most atv dealers carry it also I run tru fuel sold at mower shops lowes and home depot its cheaper than stihl and same stuff JB
     
  4. papadave

    papadave

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    Added octane reduces the chance of pre-ignition/detonation.
    I only recently bought 89 octane gas for the saw, then I add Stabil. Too hard to find non-ethanol here w/o driving. Never had an issue, and my saw sits for along time between uses.
    Maybe I'm just a really lucky SOB.
     
  5. Marshel54

    Marshel54

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    I will check with NAPA. Can't afford nor care to get Stihls $32 per gallon.

    Haven't found any non ethanol fuel in my area, but I have been told of a station that has it when I get up home. I don't know the octane though. How about it brenndatomu what is the octane of Burt's fuel?
     
  6. Boomstick

    Boomstick Banned

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    Octane is resistance to knock.
    Higher octanes(pump gas "usually") carry less energy.
    Ethanol also helps reduce detonation/knock.
    All I run is the cheapest 87 %10 ethanol gas. Everything starts runs perfect.
    Unless you are ported/increased timing there is no reason for higher octane. I'm willing to bet most still wouldn't knock on 87.
     
  7. Carbine

    Carbine

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    If you aren't experiencing pre-detonation.... then you don't need to use higher octane fuel. I have no issues running 87, but generally only use 90 because that is what is available (for ethanol free) that is.
     
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  8. huskihl

    huskihl

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    Chainsaws don't have a compression ratio high enough to require the use of high octane fuel.
    In some states, not all, premium is e-free. I use 90 octane e free because it's available locally.
    One thing about using pump 87 is that it's used most frequently by vehicles, and should be more fresh than mid grade or premium.
    If I didn't have e free at the pump, I'd run 87. But only in quantities that can be burned within a few weeks
     
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  9. TurboDiesel

    TurboDiesel

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    Have an airport near by?
    Avgas (100LL) is usually 109 octane and about $5 per gallon. and it's ethanol free.
    That's all I have run for years.
     
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  10. brenndatomu

    brenndatomu

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    This ^ ^ ^
    IIRC its 91...I hope they are still gonna carry the E free...Bert sold the station a few weeks ago. I know there is E free in Wooster too, just don't remember where for sure. Santmyers down by the fairgrounds is probably one...
     
  11. Dakota Hoarder

    Dakota Hoarder

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    interesting thought Huskihl! I wonder how long premium gas sits in the tanks at the gas stations? Are gas stations required to "take old gas of the shelf?" I don't know anybody that puts premium in there cars, I only know people that use it for small engines and that would take a lot of small engines to drain a tank!
     
  12. huskihl

    huskihl

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    Exactly.
    Like I said, premium in some states is e free. If that's the case, they should use it. In Michigan, premium is still typically 10-15% ethanol. I'm lucky enough to have a local gas station that sells e free, or rec gas, as it's called here. I've stored it for 6 months without issue. But I've noticed saws acting funky after 2 months with e 10 gas
     
  13. Woodsnwoods

    Woodsnwoods

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    Go with 91 or 93 non ethanol......non ethanol
    Being critical point. Unless you are a pro cutter or racer, you will not see the difference.
     
  14. Dakota Hoarder

    Dakota Hoarder

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    Good to know. Still have e free premium in SD! Anybody know the shelf live of e free?
     
  15. huskihl

    huskihl

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    Not entirely certain. I'd say at least 6 months in a sealed jug or can
     
  16. Ronaldo

    Ronaldo

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    And this makes all the difference, sealed containers. Not having much choice but to use ethanol blends around here; we have used ethanol on the farm for 20 yrs now in lawnmowers, small tractors, generators, over the road vehicles, etc, etc, and chainsaws....... Keep it in a good sealed container and we have had no issues or failures due to the fuel, even storing it for months.

    Sent from my SM-S320VL using Tapatalk
     
  17. lukem

    lukem

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    87 octane gasohol is all I run in my stuff.
     
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  18. The Wood Wolverine

    The Wood Wolverine

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    Agree'd! ^^^^^^



    All I've used in the past (close to 10 years now in saws) is 87 pump, which is up to 10% eth here. Have 5 ported saws (some timing advanced, some not) and a few more stock. Never had any detonation issues so no need for higher oct. Higher oct burns slower to resist detonation, it's not "better" just because of that higher number. My Tundra and Jeep all get 87 and have since I've bought them. No need to waste money.
    The saws do get started and ran about every other month at the least. A while back, one of the guys that ported a saw for me did a fuel test while chainsaw milling. He found the low octane to be faster.
     
    Last edited: Nov 14, 2018
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  19. RCBS

    RCBS

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    I recall reading somewhere that the old 372 had a comp ratio of 10.2:1. 91 is suggested octane for that ratio in an automotive application. 'Dirty' math formula is P.S.I. divided by 14.7. So 155 psi would be roughly 10.5:1. I am sure that the ratios vary by manufacturer and model. I'm also sure the difference is not measurable in 'seat of the pants' testing.

    I run quite a bit of Husky canned fuel and am happy with the way my saws run on it. My mind asks though...if 87 octane is 'fine' for their equipment, why would they use 93 octane formula in their canned fuel? If it is a 'gimmick', why would they not use an even higher octane number? My 550's manual says that 87 is fine, but also says "When working with continuous high revs (such as limbing) a higher octane is recommended". But they don't say what octane is 'recommended' for 'high rev' use. Dunno about most others, but if my saw isn't idling...it's at 'high revs'? :saw: Perhaps they mean 'pi$$-revving'? :thumbs:
     
  20. Backwoods Savage

    Backwoods Savage Moderator

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    I usually run mid-grade or simply 87. I will start buying the ethanol free as we have it here now but not sure of the octane rating.

    Also, I do always use stabil with the gas and have no problems with the gas. The gas can I just emptied yesterday was bought last March if I remember correctly. No problem.
     
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