lohring

"Try running Coleman fuel in a European engine and then come back here and make that statement again. (unless you're at an altitude of more than 6000', which brings down the effective compression end pressure and temperatures significantly )
Engines die because of too low octane. They care not about too high octane."

I specifically said Coleman fuel works in Zenoahs. I bet the majority of model boat racers use it. Only in high compression engines like the Quickdraw does octane rating matter. By the way, those stock 26 cc Zenoahs develop around 4 hp at 13,000 rpm for a BMEP of 77 psi (5 bar). Modified they develop around 6 hp at 16,000 rpm with BMEP at 94 psi (6 bar). The RCGF 40 cc engine develops 4.6 hp at around 7000 rpm for a BMEP of around 100 psi (7 bar). That aircraft engine is a higher performance engine and may need a higher octane fuel. From the manufacturer's web site: "Fuel - Use Regular 87-90 octane Gasoline or Coleman Fuel with octane boost (sorry we do not sell fuel) mixed with 2 cycle oil. Use ashless NON-Synthetic oil for break in."

Higher performance model marine engines also need higher octane fuel. Our testing on Quickdraw 26 cc engines shows significant loss of power on 87 octane fuel. We set the RC gasoline fueled boat speed record at 109 mph in 2004 that still stands. We used VP's U-2 fuel. This is a 101 octane highly oxygenated fuel that performs much better in Quickdraw engines than any standard gasoline regardless of octane rating. Gasoline is a broad description of a lot of very different fuels.

Lohring Miller