Try sizing what one of these would need to be to have a real effect, and compare it with the tiny size of these typical HHO generators. The gap is astounding. I've calculated out quite a few numbers on these, mostly because I get people asking me about these systems all the time where I work. I wish I could tell them something like "Sure, it works, you just have to add around 10 degrees more timing and 10% less fuel." But doing just a few back of the envelope calculations tells me this idea's doomed. You'd need some really extraordinary proof to convince me that a claim of this working is valid and not the result of a poorly done test or an outright con artist. Here's some of the numbers I calculated.
Amount of water needed to separate to get the energy equivalent of 1 gallon of gasoline: 2.2 gallons
Minimum amount of gasoline a gas-powered generator would need to separate 2.2 gallons of water: 3.3 gallons
Mass flow rate of the typical 1 liter / minute hydrogen generator: 5 grams per hour
Mass flow rate of a single fuel injector on a mild street V8: 8600 grams per hour - and there are eight of them.
I've done the math, and if you wanted an onboard hydrogen generator that could take a car from 20 mpg to 30 mpg, you'd need a minimum of 2500 amps. That's not a typo. If you used an alternator, you'd better get a Gilmer belt or a chain to drive it, and the 50+ hp this alternator would sap way more fuel than you'd get by burning the hydrogen. To power it, you'd be looking at a battery pack recharged by household power... and to have it last a decent amount of time, expect it to weigh a metric ton.
