Well, since this thread has migrated to water injection, maybe I can toss in my 2 cents worth.
The argument appears to be whether water injection cools the engine or increases power by reducing pre-detonation. The answer is both. By reducing pre-detonation, more fuel can be burned in the cylinder at each stroke, increasing power. However, that would overheat the cylinder. But it also happens that when the injected water vaporizes, it sucks up a tremendous amount of heat from its surroundings -- due to the high latent heat of evaporation -- making the added power practical without burning up the engine.
Without water injection, the same amount of power would only be possible using a larger engine.
For a turbine, the same principle applies -- the evaprating injected water reduces the turbine inlet air temperature, increasing its density, thus allowing for more fuel to be burned, increasing thrust.
Now, just a word of warning, I am not a propulsion guru, my opinions are based solely on basic engineering principles.
"In God we trust, everyone else bring data"