[Murcielago659]

Nitrogen is NOT FLAMMABLE. It is an inert gas, which means that it does not react to anything. Not fire, not temperature, and not any other chemical.

When nitrous oxide is injected into a running engine, the heat of the combustion causes the nitrous oxide molecules to split into two nitrogen atoms and one oxygen atom. This extra oxygen (which is extremely flammable), when mixed with additional fuel, causes a hotter combustion cycle. The two nitrogen atoms go out with the exhaust, totally unburnt. The flames that are associated with nitrous have nothing to do with it at all. They usually happen because you suddenly let off the throttle, which turns off the nitrous instantly, but not the extra fuel, which will still be injected into the engine for a split second. This extra fuel causes a sudden rich condition and sends a lot of raw fuel into the hot exhaust, which then ignites, causing a flame to shoot out of the exhaust.