RE: Percentage of Nitro in the Fuel
small Nitro increases make no difference to engine performance. From 0 to 10% a small increase in performance will be noticed. However a much better idle will be noticed. For a noticeable extra increase in performance the next step would have to be up to about 30%. When Formula 1 Pylon Racing was popular we ran 60% nitro.
Do not ever believe that nitro cools the engine. It does not. The higher the Nitro content the higher the engines operating temperature. Most sport engines meant for use in North America are set up for app 10% nitro. Most European engines are set up for 0% nitro. For average sport flying 10% is adequate. If the nitro content is increased then it may be necessary to add head shims to prevent over heating. Extra oil is not necessary. Again when I flew Formula 1 pylon Racers I used 60% Nitro, 15% oil, all synthetic.
If one is going to play with high nitro fuel then an understanding of inlet and exhaust timing, deck height and head clearances to determine combustion chamber volume is required.
Ed S