RE: gloengine nitro
For most sport model airplane applications, 10 to 15% is all you will ever need. I ran 5% nitro for years in pattern. Four strokes perform well on 20% as in a 20%oil/20% nitro YS blend. Helicopters will run up to 30% in a heli blend fuel. Above 30% you start to get into speed and pylon racing applications where needle valve settings get real testy. Racing engines are timed so that they can run the high nitro content fuels. Experts only at this level, so these engines are toast. Hope this helps.