Ethanol does not work well in model airplane engines. Second, it is extremely dangerous to use petrol in engines designed to run methanol/nitromethane/oil-based fuels. Nitromethane is much harder to obtain these days, after the Okalahoma City Federal Building bombing. The solution is to use lower nitromethane fuels, buy your fuel, or use engines set up to run regular FAI fuel (75% methanol and 25% AA castor oil). Please do not experiment with fuels. Ask people who know about fuels and do not use petrol for fuel, unless the engine is a regular gas engine. You might look up my old article on basic homemade model fuel on Google to get an idea, but please, no petrol for your own safety and those around you.