[HummerJim]

Water injection on piston and turbine engines is not new. It was used tested by Tom McHale in Mechanics Illustrated in the 50s on a '57 T -bird (yep, I'm an old fart, but I loved his car reviews). His verdict was it did nothing at all. The original Boeing 720, 707 and KC 135 used water injection as a means of increasing the density of the air flowing out of the burner cans, but it used a tremendous amount of water.
The most famous pitson engine with water injection was the Pratt and Whitney R4360 producing 3800 horsepower on the C124, Globemaster. The water injection system required ADI or ADF (anti detonation fluid), but the water injection system was disabled on all the engines in the '70s because of burnt pistons and valves due to uneven combustion caused by water injection. Anti detonation fluid was required because adding water to gas lowers its octane rating (dillutes it) while increasing the mixture's density. Water injection on the R4360 was used to increase horsepower when overgrossed, but had no effect on pounds of fuel burned..