Grumman Hellcat
 

I was just watching a documentary on Discovery Wings about the Grumman Hellcat. There was one thing that I didn't understand - They said that a modification on the original specification added a cold water injection to the engine that gave the pilot a limited boost in power for a short time.
What exactly does this mean?
All replies gratefully received.
MF

In high pressure turbocharged engines the air/fuel mixture that enters the cylinders can, in some cases, explode prematurely (before the spark plug ignites) due to the extreme engine environment conditions. This situation is extremely destructive and results in severe engine damage (piston piercing). To avoid damaging the engine by detonation or pre-ignition phenomena, water is injected, along with fuel, in the combustion chambers in order to provide a water/air/fuel mixture which not only burns more efficiently and avoids detonation or pre-ignition but also provides additional inlet air cooling and, hence, denser air. The sole function of water injection is avoiding detonation.