Ahhh, yes the good old water for fuel idea. Actually it will work, but how good, thats up in the air.
Water is H2O as most of us know. A process called electrolysis will make the bonds break up, so you are left with H2 and O (which bonds to another oxygen making O2). Now, for our engines, we would need a good amount of hydrogen. I'm thinking it would take a good 60amps to produce enough H2 and O2 to make it worth while.
Are I suppose it could be done with Ammonium, which chemical formual is NH4. The formula for that would be .........2NH4 -----> N2 + 4H2. So it would be better usuing this, but how much does this stuff cost.
Also it takes Stainless steel rods to make it work good, and SS is expensive as crap.
Its a good idea, but the initial cost will be alot. I would gesstimate a good %10-20 increase in fuel economy.
I suppose you could rig up dual alternators, one for all the truck stuff, and another to power the electrolysis. Its just how much loss in milage and power would you see from power that extra alternator.