John, I have to beg to differ with you on this. Water injection is not in the same ballpark as the various, ah, "devices" sold by J.C. Whitney and other mail order houses in the 50's and 60's. It is a proven system used on race cars, supercharged and turbocharged vehicles, and was used on some fighter plane engines during WWII. What it does is to allow, as Larry said, the use of more advanced timing and a higher compression ratio, plus it cools and steam cleans the combustion chamber while the engine is running, so you don't get any carbon buildup. Want to run 11:1 compression on 87 octane gas? You can do it with the addition of a water injection system. And I'm saying this from experience, because that's exactly what I was doing in 1978 when I was using a water injection setup on an engine that had a compression ratio of 11:1 or 11 1/2:1 and would detonate like mad until I put the water injection on it. And if you're wondering why I had an engine like that at that time period, it was built when you could still get 100 octane fuel on the street back in the early 70's. Water injection saved that engine from self destruction, and it ran happily for several more years. However, if you use a compression ratio of 9:1 or lower, it probably won't do a whole lot of good other than to reduce carbon buildup internally in your engine. And, no, water injection doesn't add power by itself, but it does allow you to add power by other methods you wouldn't ordinarily be able to use with today's gasoline. OK, I'll get off my soapbox now.
