Well, 29.93 in Hg is 14.7 psi, or atmospheric pressure at sea level.
If manifold "vacuum" is 22 in Hg, that's just under 3.9 psi.

I really do not know how much more volume our mostly nitrogen/oxygen atmosphere would have when it's at nearly 1/4 of normal atmospheric pressure. I suspect it's a pretty significant difference. My ears told me that every time I took a military hop @ 41,000 feet.

 

I moved this, as it seems to be going off-topic a bit. I do hope the OP checks back in and clarifies some things, though.

One problem is running down hard data on the web. The great majority of sites that discuss H2 addition to the fuel stream are true believers, and don't publish anything like hard data. The sites that may have some gems are like the IEEE site, requiring membership (fees) or payment for the article of possible interest (pig in a poke).

Anyway, nobody has let on about actually seeing a quantifiable increase in gas mileage with H2 injection. The only source I have found points to Popular Science magazine as the testing agency seeing negative results. I tend to believe them, but wouldn't mind seeing another outfit or two chime in.

 

I hear you.

I really didn't want to get OT so far; just try to focus on what the OP's dilemma was. Seems to me that a buck converter looks like the way for him to go, but it's not the sort of project a beginner in electronics could successfully construct and get working, even with rather complete instructions - but before undertaking even that project, he needed to do some testing, or actually a series of tests. Electrolyte concentration vs voltage vs current vs gas production vs heating; there should be an optimal combination somewhere. Nothing like 50 liters/minute, of course - not with a system that small, and with the small amount of power available.

I've seen a lot of hype and a lot of enthusiasm, and a few folks talking big gains in mileage. But nobody's said how they calculated the gains, and what all they'd done to the vehicle in question, and if they'd repeated the process on a similar vehicle and realized similar gains. I've also seen a good bit of outright hogwash and snake oil associated with it. All too often, what seems to begin as rational explanations tend to wander off into technobabble, "magic boxes" and outright absurdities.

 

I liked the website link, better than most and had pretty detailed plans. I have to admit I'm puzzled by the pairs of plates not connected to anything. Are they supposed to be charged by being in the current path and act as a electrode?

 

I was surprised by the use of device-box covers as plates. I did a quick check to see just how much more expensive they would be than cutting plates from shim stock. I found they are actually less costly than equivalent area of small quantity shim stock.

One should waste as little of one's money as possible on a folly of this nature, after all.

 

On another note, I'd really like to see some test results on these mileage improvements. Your Dodge must have a big engine.

Just for some figures, a 5 liter engine cruising at 2000 RPM will require 5000 liters of air/fuel each minute. Increasing the mileage by nearly 50% means lots of extra fuel somehow getting made.

Other than the stalwarts who maintain they have discovered secrets that allow them to break down water faster than physics says it can be done, this just does not seem possible. I really wish somebody would demo one of these systems under controlled conditions.

There's no real mystery here. The OP admits tampering with the oxygen sensor so any mileage increase can be explained by the engine running much leaner than is good for either the engine or the environment. Given that the gas that they inject burns without producing any excess oxygen I can't see the reason why they find it necessary to tamper with the oxygen sensor, but then I suppose if they didn't they would not see these dramatic mileage improvements.

 

That is one of the mysteries. No amount of leaning out the mixture can give mileage increases nearly as large as what we see anecdotally reported. And no outsider can get any increase at all when using at least one of these systems.

When pressed for numbers and details, the response from the water to hydrogen community seems to be to steal away into the night. If there is anything of value going on here, they certainly know how to make it appear exactly like a scam.

 

It also doesn't help that science seems to be a weak point with the majority we get here, to whom the Laws of Thermodynamics seems to be a new concept.

I still have an open mind, but the data is mighty scarce. I can buy that something in the chemistry is being tweaked, but I need repeatable numbers to be convinced.

 

The only report I can find is from Popular Mechanics, who failed to see anything but an increase in current with the electrolyzer turned on. No increase in mileage noted.

Part of the problem is the sheer numbers of sites all reporting the real deal in water-to-fuel technology. But they all tend to give conflicting reports on how it's done. One even purports to using Orgone energy (remember Orgone boxes back in the 70's?).

I particularly like the ones that advise changing the ignition timing. One says to retard by 10 deg, another 70 - 80 deg, and another says to retard 180 deg. Then you have to determine T, the time after the explosion that the implosion (?) occurs, and add that as a further ignition delay. Kinda hard to produce power with a valve or two open..

 

The only report I can find is from Popular Mechanics, who failed to see anything but an increase in current with the electrolyzer turned on. No increase in mileage noted.

For everyone's reference, the Pop Mech online article is here: http://www.popularmechanics.com/automotive/how_to/4276846.html