Air cooled engine fuel

[KevinB]

Av gas octane is tested at 10,000 feet altitude and pump gas is tested at sea level. Very little difference in total octane between the two.

Av fuel is dry with a little lead. Your small gas engines are designed to run on 87 unleaded fuel for the most part.

---------kevin--------

[Maddog5150]

Click on the link already provided, read the questions and answers provided by the President of VP Racing Fuels. It could be just marketing but I have used VP Fuel in my 427 SO without any problems and my buddy uses 105 octane VP Fuel in his dirt bikes. VP Racing Fuel has a good reputation, and I trust what they say.

lol. Thats because you have a 427 and your buddy probably rides in the desert.
The 427 is not exactly a cool running motor and when you go WFO, its probably going to run into some pre-ignition/detination if you were running an 87.
Dirtbikes are HOT and blowing a hole in a piston in modern 450 4-stroke is going to cost more than an American V8 so running all day in the desert where your bike is at high RPMs and in a hot environment, it makes sense to prevent pre-ignition/det by running something more resistant to heat.

A lot of people dont understand octane ratings or what they do. Young kids with a honda and a coffee can exaust think that adding racing fuel will make them run ten second quarter miles when in fact they could be hurting thier car. Its really simple. Higher the number, more resistant to heat. You throw something like that into a fuel system not made for it, bad things can evetually happen. You put in a fuel that isnt resistant to heat into something that is really really hot running, lets say a 427 thats bored 60 over , the massive amount of heat generated by the engine can ignite the fuel before its meant to go off during the compression stroke. that can start a hot spot and start damaging parts or the engine. I've seen pistons with jaggen holes blown through them from long terms effect of pre-ignition.
On the flip side, your spark plug is supposed to ignite all fuel. If you run something too resistant to heat, you wont get full burning for the power stroke. the excess and unburnt fuel continues to burn late down the cylinder and maybe well into the exaust stroke. This will lead to 1, a waste of that cash spent in the 1,000,000,000 octane level racing fuel and also lead to excess carbon deposits which will effect your engine long term.
Less someone has something custom/built up, use whats on the manual

[Californio]

Again the Stihl Dealer recommended that I run what they carried, TruFuel 92 octane, go figure. VP Racing is 94 octane. To each his own, everyone has his opinion.

I did burn a hole in the #8 piston of my Marine 440 using the rot gut provided at the fuel dock and it had industrial heads for better cooling with large seawater heat exchangers. The hull now runs a Cummins B series diesel engine.

In my opinion without a computer to protect the engine, modern pump gas is the chits.

On Edit: The reason I was at the dealer in the first place was due to a Stihl recall. The dealer had always specified to use the best 92 octane pump gas but the recall dealt with ethanol causing the fuel cap sealing system to swell and not seat properly on many of their models, thus a new fuel cap sealing system. The dealer had never urged ethanol avoidance in the past but now they are, take it for what its worth.

http://news.consumerreports.org/home/2011/05/stihl-recalls-23-million-trimmers-blowers-and-other-outdoor-gear-recalled.html

[SoCalJ]

I'm just looking for something that stores well and will not go bad so quick. From a cost perspective it looks like Av gas is the way to go...5-6 bucks a gallon compared to 5-6 bucks a quart for VP or Trufuel....

[Bobby B.]

So, to circle back around, I wonder if i have, say, a jerry can that's been stored a while and not rotated out, if adding a can of this stuff to it will freshen or liven it up some so it's once again suitable for use?

Kind of like a supercharged version of octane boost?

[SoCalJ]

I think your best bet is to treat it with something in the beginning. As far as I know there's no magic pill for bad gas....
I've used Stabil, Mecury Marine stuff, and Seafoam in my boats with no problems for 6-7 months of storage. I've notice the Stabil treated gas in the genny turns yellow and smells wierd in about three months. Still runs but I don't like it. I've had problems with gummed up pilot jets on two motorcycles and don't want any problems with the generator.