I would liove to hear the outcome of your experiment, mine didnt go all so well. i tried a fuel/water hybrid in my BBF jet boat....
How do you think i got the name "Rodbender" 
In my reading and understanding of what goes on, two things might have caused this. 1. Due to an excessive enrichment of the fuel/air mix, the timing was not retarded enough to allow for proper ignition. For example, if you were set at 8 deg before top dead center, and the plug fired, the resultant explosion what be faster, actually trying to drive the piston down on the up stroke, thereby causing a bent or broken rod. 2. You possibly didnt run a leaner amount of fuel, which would do the same thing. Thats sort of the point of this, if your running leaner, but getting the same results, viola, better fuel economy. So let the experimentation continue!