I have a friend who has drunk this kool aid and I don't have the heart to tell him just how wrong he is.
It is nice to see Popular Mechanics tie up with Dateline NBC to debunk this horrid example of bad engineering:
Why Water Won't Improve Your MPG: A PM and Dateline NBC Investigation
I get mail. Hundreds of pieces of mail every month, and that includes e-mail, paper mail, the occasional voice mail and even a smattering of faxes. For the last two years, an unhealthy proportion of that correspondence has been about the same thing - making your car run on water instead of gasoline. With fuel escalating to historically high prices, followed by the global collapse of virtually every market, people are inclined to search for a way to reduce their monthly expenditures for gasoline or diesel. Which, of course, is perfectly understandable.
Over the years, I've tested plenty of gadgets that purport to reduce fuel consumption. None of them worked. None. Lately, I've tinkered with a number of them that rely on the same principle: using electricity from the car's battery to electrolyze water in an onboard cell and burning the resultant hydrogen-oxygen mix in the engine. In theory, the burning hydrogen will provide extra energy, reducing the amount of gasoline you need to move on down the road. There are dozens of websites, and dozens of people on Ebay touting these devices, guaranteeing, depending on their level of chutzpah, anywhere from 15 percent to 300 percent improvement in fuel economy by simply bolting on one of their devices.
This doesn't exactly rival string theory in it's complexity. You can build a serviceable hydrogen generator from an old peanut-butter jar and some leftover copper pipe or roof flashing. There are plans to construct this device that you can get online, too. Just use some aquarium tubing to duct the hydrogen-oxygen mix (usually abbreviated as HHO) into the intake manifold, and you'll see the gas gauge stay at "Full" a bit longer - or so they say.
When these devices first hit the Net, I had an immediate opinion: Rubbish. I discussed the theoretical science a while ago. It's bad science. This malarkey boiled down to perpetual motion: something for nothing. Essentially, it takes more energy - in the form of the chemical energy in the gasoline you're burning in the engine, to spin the alternator to make the electricity and generate the HHO - than you get back. In fact, it's not even close: Multiply all the inefficiencies in that system and you only get a few percent back, certainly not in excess of 100 percent.
A bit more:
I've been tinkering with a couple of homemade and commercial HHO generators. I have instrumented several cars with HHO generators I can switch on and off, flow meters, scan tools and instantaneous mileage displays. I've tested them on the road and on chassis dynamometers, and have never seen any improvement. None.
They take it to a professional installer and have the deluxe system installed and then return to the dynomometer with the following results:
In fact, if you look at the EPA tests with the system switched on and then off, there's a tiny increase in fuel consumption when the system is turned on. I attribute this to the 15 amps or so of current the electrolysis cell consumes to produce hydrogen. That current uses horsepower to spin the generator, and that consumes gasoline. The hydrogen "boost" couldn't even compensate for its own losses.
TANSTAAFL writ large for all to see. And the ironic thing is that the very electrochemical property that makes stainless steel stainless also makes it the absolute worst choice for electrode material if you are trying to do electrolysis. Platinum or Palladium is far far better.
