I'm sorry, but you have got this completely the wrong way round.
Adding nitro is the glow fuel equivalent of using a higher octane number. Everyone who drives knows that if you use too low an octane number (RON) fuel in your car, it can "pink" or knock because of pre-ignition. Modern engines compensate for this with knock sensors that adjust the mixture and the ignition advance/retard. higher Octane numbers permit higher compression ratios without ignition due to compression heating (pre-ignition).
While correct on the auto fuel, very wrong on the effect of nitro in model engines. Operation with increased nitro requires lower compression on the engine, not higher compression.