The question is not whether you could get an engine to run on a water and gas mix but whether you can produce more energy with that mix than the gas alone would produce. Gasoline normally has some water in it and of course the air contains varying amounts of water vapor and thus all engines run on a water and gasoline mixture, that's why you get water leaking out of your tail pipe. It sounds like an interesting project, I will be glad to have a skeptic take a look at it!