And here in the US is where most of Cox engines were sold. Physics overrides location and price of fuel in the use of model engines. Small engines give off their heat very quickly and the use of high nitro fuel is required for maximum reliable performance. that's why Cox made their fuel at those nitro percentages and why other companies made high nitro fuels in small 1/2 pint cans. Strictly for use in 1/2A engines. Yes a 1/2A engine will run on FAI fuel but lousy. You'd have to increase the compression ratio and that's a bit difficult to do.

I recommend you get one of Clarence Lee's or Dave Gierke's books on the model airplane engine and see what they write about small engines and nitromethane.

Also, I lived in Japan for 4 years where nitro was very expensive. Even they ran their little engines on high nitro fuel. If you ever get your hands on an Enya 049, look what the manufacturer recommends for fuel.