Has anyone tried water injection systems to save fuel?

I don’t recommend it. Your fuel could become contaminated from water injection, unless you can obtain distilled water from a sealed container. A pulsed injector should supply up to 2 millilitres of water at each intake cycle.

According to all the News broadcasts all around the U.S. NO they Do not work! Just make sure your tires are properly inflated, that your vehicle is properly tuned up, your filters are clean, and keep your foot out of the floor, gentle take offs from standstills. No excessive idling either, if you have to be stopped for more than 10 minutes, it is better to un-start your vehicle. Then restart when it is time to go.

No

Rolls Royce tried it with the Merlin [Spitfire and Mosquito ] engine during WW2 and obtained slightly improved results. Not sure if this is what you mean.

The principal relies on heat from the engine to quickly force water to steam and use the cooling ability but the problem is the wear and tear on ferric parts. In modern steam engines alloys like stellite (cobalt nickel or chromoly) are used for strength and non corrosion. Cobalt is great! The increase in pressure from steam can’t be maintained in an internal combustion engine burning fuel to make expanding gases because those gases cool too fast and don’t burn fully as as rapidly as designs require. It has been used as a means of cooling some engine parts like some turbo’s and exhaust parts and in some turbines but I don’t expect it would give any major savings in fuel. It was not for that purpose. Best results will be had from getting away from expensive fuels like petroleum.