ref Raymond D: Why water inject a diesel?. On one, I work on, we inject One Gallon of Water every 15 secs. To cool the intake charge, 60 PSI of boost.. The area between the turbo discharge, and first water nozzle burns the paint off. It's a Pro Stock Pulling Tractor... Bruce Be sure to cover your Cone Shaped Hat at a Pro Stock Pulling Tractor Meet, LOTS OF SOOT