I don't know much about the fuel they dispense at the Reno Air Races other than it smells different and makes the planes go like stink. I live in Reno and never miss the race every year.Avtur or Jet A1 is the diesel 'type fuel' used in turbine engines.
Avgas over here or '100-130' (color green) is the stuff Theon is taking about. The lead in the fuel does four things - inhibit knock, give you a bigger bang, lube up the upper cylinder and gum it up (eventually).
Engines should be able to run, higher compression and more advanced timing.
Avgas sold in the US - is called 100LL or Low lead (color light blue) has less lead per gallon.
The purple Avgas 130 -145 (color purple) is the best stuff still made. If your able to get a hold of it, let me know. They only really make it for the reno air races now.
engines not tuned for Avgas will usually cause some damage - whether its burnt out exhaust valves etc.
RC engine run on a nitro mix, a methanol-based fuel with nitromethane and oil added
Ditto: Jonny is right on with this advice but you need to be careful and not go too lean. That is one problem running the 100:1 ratio. To get things right you really need to lean out the fuel/air mix because of the more fuel, less oil condition you are now giving your engine. Just don't over do it. A lean burn can shorten the life of any engine.Hi Nevada. I broke my new engine in running opti 2 @ 80:1 from the get-go for half a tankful (approx. 1/4 gallon) then went directly to a 100:1 mix. Over 200 miles on this mix my plug is a perfect golden-brown and the engine runs surprisingly cool. I suggest raising the c clip position on your carb needle (and possibly going with a smaller jet size) because running lesser amounts of oil per gas ratio makes the mixture richer (more gas in a given gallon).
Once again, to put the myth of high octane fuels to rest:
The higher octane number does not give any more energy content per unit of fuel. You will not achieve more power or fuel mileage, nor will there be any better effects of burning higher octane fuel in an engine designed for regular fuel.
It ONLY means the fuel is less likely to auto ignite, meaning that the air/fuel ratio will not detonate before the spark plug fires it. You only need higher octane when dealing with an engine that has a higher energy input in to the fuel, or a higher activation energy.
The higher octane fuels are harder to ignite, meaning if you do run them in an engine that will not detonate on a lower octane fuel, it will only lead to a more incomplete combustion. This WILL lead to more deposits in the engine, and you will get less power from the engine because of the incomplete combustion. On the inverse side, running a lower octane in a high compression or forced induction (turbocharged/supercharged) engine will give you detonation and auto ignition because the energy the engine is exerting on the air/fuel mix will be higher than the combustion energy required to combust the fuel before the spark plug fires. This can quickly destroy an engine.
So if you don't have a high compression engine and you're not experiencing knock, then don't use "premium" fuel. I use quotes around premium because I don't want people to associate higher octane numbers with being better. It's a myth.
I absolutely hate hearing people say that they fill up with "premium" every once in a while to keep the engine clean and healthy. They have no idea why they're doing so. Probably because they associate premium with terms like best, clean, healthy, etc.
If the premium fuel in your country really is filtered better, then get a good fuel filter and prove it. I seriously doubt it's anything more than another myth, but then again I don't know anything about how Australian refineries process their fuel, so I may very well be wrong. Im skeptical at best.
Nevada,Thanks Jonny and Tom. I do live at elevation though. Around 5000 asl. Would that make a difference in the clip position?
ditto............A little accidental science. I raced a GSXR 600 for 3 seasons on 87 octane. One weekend i signed up for a 2 hour endurance race i had not planned to do and had to go buy fuel in a hurry. I could only find 93 octane so i threw it in and raced. The bike felt off but endurance racing is so physically and mentally hard i couldn't really tell. When i got home we put the bike on the dyno just to make sure it was ok and it was down on power from my last dyno session and I suspected the gas. We drained it completely and put my normal 87 pump gas back in and gained back exactly 5 horsepower on the dot. As described above octane is a flash retardant to prevent pre ignition in high compression engines. You will actually get the most horsepower from the lowest possible octane before pre ignition.