I would not run leaded fuel. 100LL is low lead but it's still lead. I don't think the average Joe even understands what octane is.
Octane question
- Thread starter pistolpeta
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Shower and laundry. If I'm cutting a lot/milling I'll use non-corn 93.
I was an Organic Chemist, I've smelled far worse than 100LL. Stuff that 1 wiff would kill you, I avoided smelling that one (phosgene)
Pat Burton
ArboristSite Lurker
I use 91 octane pump fuel. Good mix oil in my 490. All my 2 strokes are stored dry. I add a couple of drops of fuel preservative to an almost empty tank then run dry. Storage=3 months or longer then fresh fuel.
That's not been my experience.
Right now I'm on day 10 of running on generator. (thanks PG&E and mother nature). It's 25 years old and has seen nothing but E10 for its entire life. Because of where I live this generator gets a fair amount of use but if I'm lucky it will sit for 8 months a year. It still has all the original fuel system parts and runs perfectly. I've not even had to rebuild the carb. Exactly zero of my saws or other small engines have had a fuel system problem.
Don't get me wrong, I think ethanol should not be in gasoline. I would run E0 if it was readily available and not too expensive. But as with the OP, neither is true where I live. And E10 works fine.
You are lucky. I have a generator that I use a few times per year year mostly during hunting season. I always run non ethanol in it. A friend borrowed it and filled it with E10 last year. I didn't even think about it and laid it up with stabil and fogged the motor like I usually do. This season I pulled it out and it would not start. In addition it was leaking fuel from the fuel line when the petcock was turned on. Fuel line was dried out and cracked and the carbs float bowl was full of crusty white gunk. A carb rebuild kit, fuel filter and fuel line latter it's running fine again.
Chainsaws are even more sensitive with their rubber carb parts.
100LL is only "low" lead compared to other avgas which had tons of lead. It's still a lot of lead.
Stock saws do not need all that much in the way of octane, and the other qualities of lead (like lubricating valve seats) are not needed for two strokes. Racing two strokes run unleaded race gas. Avgas is made for very different engines than car or chainsaw engines.
It's also expensive and you'll have to find an airport willing to sell it to you. If you're going to go to that much trouble and expense, just go buy some of the boutique canned fuel.
And you're right most people do not understand what octane is.
Stick with the ethanol free. The ethanol will soften your fuel pump diaphragm and make it stretch then your saw won't start. I use 93 octane ethanol free and Maxima full synthetic oil at 32 to 1 ratio in the hIgh performance saws like Dolmar PS-5105SC and Husqvarna 346XP. These saws are turning 14,500 rpms and need the extra lubrication to prevent P&C scoring plus the reduction of engine temperature by 10 to 15 degrees. An octane rating is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without detonating. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates gasoline's capability against compression.
You've done an analysis?
We used to analyze fuels as part of an analytical chemistry experiment..........
Mixed 100LL is far less expensive than the canned fuels.
100LL was recommended as fuel in the old Chevrolet Hi-Perf Manual (Chevy Power). It had all the high performance parts/part numbers listed by engine type (big block, small block, cosworth DOC 4....)
I still run it in my 68 Camaro. It has an 11:1 69 LT1 motor that has been decked and heads surfaced, compression is somewhere about 11.5-12:1. I can get by with cutting it 50:50 with pump premium.
Years ago I could pull right up to the pumps at the airport and do a burnout on the tarmack. The kid pumping gas was happy to see me. 9/11 put an end to that.
Every small airport around me will sell 100LL. There was one that used to have the green 130 octane fuel.
thompsoncustom
ArboristSite Operative
This....
Running 110 or 100 or 93 does nothing for the engines performance/health unless the engine has a high enough compression ratio to require that octane rating.
It actually reduces performance to run a higher octane rating than required on a dyno but in real life you won't notice any difference.
I bet there isn't a factory chainsaw out there that requires u to run above 87.
Doesn't all the above come down to IQ at some point tho? Maybe i'm confusing book smarts with common sense tho
I use Klotz octane booster. 1 Oz per gallon raises 2 numbers…not points. Most octane boosters only raise 1 or 2 points. That means 87 goes to 87.2. I make 90 octane e-free with 88 octane e-free pump gas and Klotz.
Never has let me down.
JQ
Never has let me down.
JQ
KodiakKen
ArboristSite Operative
I run all professional series stihl saws with stihl ultra oil and I use the highest grade pump gas i can find ethanol or not. Higher octane burns hotter and faster. Leaving your saw cooler. Ask any mechanic. My uncle was a dealer and mechanic in Mississippi. If I'm going to pay $1600 for a saw I'm not going to go cheap on oil or gas
This....
Running 110 or 100 or 93 does nothing for the engines performance/health unless the engine has a high enough compression ratio to require that octane rating.
It actually reduces performance to run a higher octane rating than required on a dyno but in real life you won't notice any difference.
I bet there isn't a factory chainsaw out there that requires u to run above 87.
Doesn't all the above come down to IQ at some point tho? Maybe i'm confusing book smarts with common sense tho
"I bet there isn't a factory chainsaw out there that requires u to run above 87."
Knock knock, anybody home?
Det.
Det who?
Detonation!
I bet that most all advise against 87. Stihl recommends 89 or above. Stations don't sell 89 anymore, so that means 91 or 93 pump gas
From 038 owners manual and 024/026 shop manual, respectively (90 ROZ (89 pump gas) or above.)
Is that cost effective?
thompsoncustom
ArboristSite Operative
Like I said requires it. They can state you should use 93 octane but that doesn't mean that the engine requires it and I haven't seen a factory saw come with enough compression to need it.
Did you just read the literature I posted directly from Stihl?
"Fuel with a lower octane number may result in preignition which is accompanied by an increase in engine temperature. This in turn, increases the risk of piston seizure and damage to the engine"
That is vebatum direct from Stihl, but what do they know......
thompsoncustom
ArboristSite Operative
Did you?
May is not the same as required. The required octane rating could be 80 at the factory compression specs unless you have proof of otherwise? Of course they are going to be on the safe side probably by a big margin.
I fell like this is a debate that we should end at some point and I wouldn't mind sacrificing a saw to test this out and see how far the octane can be lowered before engine damage starts to occur.
May is as in may happen.
See attachment #1, "requires"...... brand name gasoline ......regular branded unleaded gasoline with a minumum number of 90 ROZ......
O.K. I'm wrong, Stihl is wrong, you are right. Carry on.
thompsoncustom
ArboristSite Operative
Ah I see maybe I worded it wrong in a earlier post I didn't mean the company required it but the mechanical requirements of the engine.
I will say that there is no reason to bicker about something we can easily prove or disprove. I have a saw I planned on putting a new top end on anyways which would be a good candidate as it has good compression and I'm not worried about smoking it.
Seems easy enough to do get some 87 octane and keep lowering it till it runs into problem or trashes the top end completely. I'll have to get it all on video and post it up on here, regardless of the out come should be good information for everyone on here and will put this to rest.
