[Honda100]

I didn't bother reading all 26 pages, but just my experience. The only way I was able to get FE benefits from water injection was by increasing the compression ratio (of course not easy to do), advancing the timing, and then using the water injection to surpress the knock that would definitely occur with a 13:3:1 engine with timing at 27 BDC. I managed around 30-32 mpg from an original 25-27. Of course though, my car had water injection because it was a drag car, and the engine had a ridiculous compression ratio for the same reason. Anything but a fuel saver in purpose.