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RJR49

100 LL

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RJR49

The local airport will sell me 100 octane low lead fuel. I know you can't use it in a road vehicle but I think it's legal off road. I've heard that 100 Octane is too much for small engines. Any thoughts? 

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Achto
38 minutes ago, RJR49 said:

I've heard that 100 Octane is too much for small engines. Any thoughts?

 

The greater the octane is the slower the fuel will burn, just the opposite of which most people think. To compensate for the slower burn you most increase the compression or advance the  ignition timing or both. Running a greater octane fuel in an engine that is not designed for it will not damage the engine, but you will loose a little power. Running low octane fuel in an engine designed for greater octane will cause pre ignition and will eventually cause damage. 

I don't know what is available at the pump in your area, but I always run premium 91 no lead gas with no ethanol. I know this is not always an option in some areas. 

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midpack

I ran 100LL in my off road race bikes (Enduro/Hare Scrambles) for many years with no problems. love the smell of race gas!!  :)

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Mower Man

My 1958 Cessna 182/A was designed to run on 80 octane aviation gas.  They stopped making 80 octane gas about 10 years ago and it runs fine on the 100 Low Lead Aviation Gas.  In fact the airplane runs fine on 87 octane Auto gas from the US or Mexico.  The only hitch is the ethanol sometimes in Auto Gas so the advise is to not use ethanol containing gas in the airplane if the airplane is going to sit for more than a few days as the ethanol deteriorates the rubber seals.

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953 nut
1 hour ago, Mower Man said:

going to sit for more than a few days as the ethanol deteriorates the rubber seals.

Same it true for our beloved :wh:

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rick

I have used 100 LL in my small engine equipment with no problems. Stihl, Echo, Briggs, Kohler and Onan. I was getting the daily test check fuel from the Town Airport, they can't put it back in the bulk tank so it ended up in 55 gallon drums, which were a hazard at the town shop. My free gas ended when I recommended my buddy there for a better job. The only minus, and it is a small one, it may cause some extra deposits in the combustion chamber. I wish Trump would end the ethanol blend fuel, it's not good for anyone but the ag industry.

I'm back to Shell 89 )octane now, except the two stroke which gets 93 Octane. Adding the mixing oil to fuel drops the octane rating right of the bat, so I start with as high octane as I can. 

 

i sure wish I could use 100 LL in my Subaru with the 10.7 to 1 compression ratio 3.0 six cylinder engine!

Edited by rick
more info

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