Use Gasohol or Recreational Fuel ???
 

There is place nearby with alcohol-free mogas, 90 octane, $4.15/gal.

Premium is $3.95/gal locally.

What do you think is best, the rec fuel or ~5% ethanol 93 octane premium mogas?

This is for a 100hp 2-cycle engine.

I thought the arrow recommended 100ll avgas.. ?

The old dealer spec book from ARROW AMERICA Inc. of Sanford, FL, states 96-98 mogas, or 100 Avgas. Perhaps you think I should go with the 100LL? That wasn't even a consideration until you mentioned it, thanks.

Was that octane "RON" or "R+M/2"

for just .20 cents a gal more use the alcohol free gas,its just better.octane rating will not give more performance,its just allows your engine compression to be higher for more performance.
best regards,eddie.....

The standard in the US and Canada is R=M/2.

Is the ethanol more likely to vaporise ? so carb icing and vapour lock in that warm Florida sun ?
I guess you are close to sea level.
does ethanol affect the rubber hoses and pump diaphrams valves etc. and does it mix with oil well. and are there any deposit differences
then it's engine manufacturers reccomendation then, does it store well in cans and fuel tanks... then finally
how much bang per buck ?

i agree the standard here is pump rating (R+M/2), but I have seen several manuals listing the Ron rating and is interesting converting between the two ratings.

The Marathon Recreational Gasoline (ethanol free) that you refer to WON'T EAT UP YOU GAS LINES, RUBBER PARTS, FIBERGLASS FUEL TANKS, ETC.

http://www.marathonpetroleum.com/bra...0314MAR019.pdf

Me!? I would use whatever had NO ethanol, check the price of avgas at the local airport too, it might not be that bad, and you can just taxi over to the pump. :)
that is what I did at Bensen days rather than drive into town for auto gas.

When I recently started looking for fuel to run in my HIRTH F30 engine, I did find in the Hirth Operators Manual, a refference to using the "RON" octane system. I had to convert this to the US "R+M/2" system. There is a difference.
So, long story short. I settled on using High test (93 octane) Ethanol free from a local source.
I did speak to Matt at Recreational Power and he stated I could use the 100 LL Avgas, but that the LEAD will shorten the life of the plugs and would build lead deposits on the top of the piston. His recomendation was to use the Mogas and if I was on a cross country trip, the occasional use of Avgas would be ok.
Thinking about the lead deposits on the piston, if heavy enough could raise the compression ration slightly. Higher compression would requirer higher octane to prevent detonation. I know this might sound crazy, but when I was a teenage, and raised in rural Tennessee, we cut wood for out heat source in winter months. It was noticed that after several years of use, the chainsaws would become harder to start , so higher octane fuel was used to help this situation. and occasionally if someone purchased lowest octane fuel a saw would get into detonation and destroy a piston.
So when a saw would start becoming harder to start and requirer high octane, we would pull the head and clean the buildup off the piston, and the saw would return to running properly on the lower octane fuel.
Oh! I might add that this was all before the introduction of the modern "unleaded" fuels.

i noticed that when I used 100LL on my Hirth it started hard. I only tried it the one time, decided the engine didn't like it for some reason.