I know that deisel engines have water injected into them (at tractor pulls) however I don't know what benifit they gain from this. I also know that back
as early as the Model T guys were getting water vapor into gasoline
engines by using simple vacuum jars piped to the intake( my Dad messed
around with this). In the early fifties there was an outfit that sold a
jar type set up to accomplish the same thing. Since water vapor is
a combination of Oxygen and Hydogen it might be intresting to know
what does happen to it at combution chamber temps, and what gain
if any is derived.