Octane rating question

100LL,..... meaning av gas? I didn’t know it was oxygenated. That’s what I been running for the last several months! In all my saws & one is a 562auto tune.I’ve got 93 E-free(supposedly) available, but really like the smell of av gas & canned fuel. If you think I should quit running av gas say the word. Is there something I could add to get that cool smell though?

 

Quiet the contrary.

 

If the 562 runs ok, you’re probably fine. Just pay attention to signs of it running hot

 

Thanks

 

You could try Klotz KL-200 Original Techniplate 2 stroke oil if you want to treat the smeller to sumptin nice

 

I know this as truth too. Unless your CR is high enough ( or have a high octane fuel setting on ignition as some 2 stroke snowmobiles have) to warrant high octane fuel, you actually lose power by running anything higher than 87. I've not seen any saws come from the factory with CR high enough to warrant anything but 87.

Like you, my saws run on 87 . I've got a 19 or 20 yr old Stihl 029s that has really only ever seen e10 87, aside from a couple of cans of canned e free premixed higher octane stuff. That 029super has never been rebuilt and has great compression. I only use synthetic oil as well.

 

This is true. Remember, that even if the strains say they have e free, that when the tablet pills up and it has e10 in it, they have to take the e10.

That's why you'll see guys do tests on supposed e free fuel and find ethanol.

 

Well, unless you use 85 in a saw made for 87. Most don't have that available.

 

Also remember, If you are buying from a station with blender pumps, the first 2.5 to 3 gallons you pump is whatever the last person bought. Not a huge deal if you are pumping in to a 10+ gallon tank in a vehicle but makes a huge difference in the first 5 gallon can you fill. When I buy E free for my saws and trimmers I top the car tank off first to clear the line so I know what I'm putting in the cans.

 

The E-free pumps around here are dedicated pumps, but it is 89 octane. I wish I could find 87 octane e-free, The few times I have used 87 with corn the saws run just fine, including the ported ones.

 

The key word is "Need". If it's not pre-detonating, you don't need it. Like you said, many engines built for competition need higher octane fuels due to higher compression ratios, forced induction, etc. but the higher octane fuels they are running are still the lowest octane they can get away with running. As to always going up but never down, running too low an octane for a particular engine can cause damage, running higher than you need just loses power until your burn gets so slow that you are detonating in the exhaust so it's generally a safer option if the ideal octane rated fuel is not available.

 

Not arguing here at all, just clarifying. Octane is a measurement of a fuel’s resistance to ignite. High compression engines may “require” a higher octane rating to prevent pre-ignition. But they’ll run best with the lowest octane fuel that doesn’t knock. There is actually more power in lower octane fuels.

 

Sunoco Race Fuels
Fact or Fiction?: Premium Gasoline Delivers Premium Benefits to Your Car

Eta: From the manual for my Husky:

• The lowest recommended
octane rating is 87. If you
run the engine on lower
octane rating than 87 so-
called "knocking" can occur.
This leads to an increased
engine temperature, which
can result in a serious
engine breakdown.
• When working at continuous
high revs a higher octane
rating is recommended.

....and from the manual for my Echo:

FUEL STATEMENT
Gasoline - Use 89 Octane [(R+M)/2] (mid grade or
higher) gasoline or gasohol known to be good
quality.
Gasohol may contain up to 10 % Ethyl (grain)
alcohol or 15 % MTBE (methyl teriary-butyl ether).
Gasohol containing methyl (wood) alcohol is not
approved.

 

Do they still drop a big pickle in Dillsburg on New Years Evve??

 

Yep. Haven't been there for a few years. I grew up in Pickle town.

 

I run 87 octane, corn liquor infused, dinosaur juice in all my stuff. The 2-strokes get synthetic oil mixed to 40:1. I have never had a fuel related issue (other than me not filling the tank) in anything, ever.

My dad, the cheapest person I know, who heated his house for 30 years with umpteen gazillion cords of wood, only ever ran the cheapest fuel he could get (meaning 87 octane) through a Homelite 360. That saw will still try to tear your arm off if you don't give it the proper amount of respect when starting it.

The only reason you would ever need higher than 87 in a saw is if you dramatically advanced the timing and/or increased the compression. There are certainly some saws out there that need it, but you don't buy them off the shelf. That's not an opinion....that's science and engineering. Manufactures saying to use 89 is probably their way out of a warranty claim for "improper fuel".

 

I run 89 or better in my saws
Ethanol is a fuel that burns well so I use it all day long.
What I don't do is leave it sitting around as it is hygroscopic so my last fuel up of the day is ethanol-free fuel.
Kinda pricy from the big box store but it sure beats cleaning the jello-like goop of ethanol-water globs from the bottom of fuel bowls and jets of carbs.
Plus aluminum corrodes easier in a high humid environment.
If a gas can of mix starts getting old I mix it into the car's fuel tank.