He didn't *ask* your opinion on whether or not this was a scam, he asked *how* to do it. Maybe we already have oxyhydrogen generators, we already know that this works, and we don't need knuckleheads to tell us it doesn't.

I'm interested in converting a natural gas or propane engine to oxyhydrogen, and *not* augmenting a gasolene engine. Is it just a matter of changing the jets?

I would think (I Am Not An Automotive Powertrain Engineer) that if you piped the gas directly into the carb just above the throttle plates (might be a vacuum input there), it would just suck it in and use it in the mix. Articles I've read suggest that you need to retard your spark due to the increased volatility of the mix, and it sounds like you already know how it can mess up closed-loop oxygen sensing emission controls.

Good luck!