Because I've ventured into the HHO crap many times from a chemical and scientific approach in many forums I've grown tired. There are many sound physics and other scientific methodologies applied that have more than proven that the many methods available on the net do not work regardless of the claims by many. Below are links to a engineering forum that have other links to such test. Dr. John Heywood from MIT has done such tests available on the SAE site (for a fee as all their papers are) that show all the test and the methodology. What cracks me up is the slyness as to how the "water for fuel" site lists his name (recognizing the clout Dr. Heywood caries in the automotive field of engineering) and an unrelated paper related to hydrogen in general as a fuel from some papers Dr. Heywood has written having nothing to do with HHO but the pure compressed gas of Hydrogen or hydrogen fuel cells. Here are a couple links to read that will carry the reader to many others:
CR4 - Thread: The Unlucky 13 HHO Lies
CR4 - Thread: HHO Update: Dennis Lee Out of Business
This video is based off what the basic principles of the I.C.E. functionality with the math involved. This is a ridiculously simplified method to get the point across, but you'll find it's validity if you have any understanding of basic physics and an base understanding of thermodynamics and chemistry.
http://www.youtube.com/user/Silverad.../5/dISUpy6uNHw
There are 5 or so in this series. Of course the true believers will always find a way to disagree with real math and science.