Some engine tuners prefer to inject a mixture of water and methanol into the intake system. Usually 50% methanol by weight is used. This provides the desired detonation suppression while also providing maximum horsepower. Methanol is both hygroscopic, which means it absorbs water, and miscible, which means it mixes well with water. It is also much more volatile than water, which means it vaporizes much quicker.
This vaporization further reduces the temperature of the intake charge, but it occurs before the combustion chamber is reached. Once the combustion chamber is reached, the atomized water droplets vaporize so temperatures are still reduced in the combustion chamber. But methanol is also a fuel and thus provides extra horsepower as well.
