........HHO works by doing part of that task chemically; besides being itself a powerfully flammable gas, the free hydrogen in the intake stream does a couple of things 1) it acts to lower the surface tension of the atomized fuel droplets in at least two ways, and it chemically hydrogenates the longer chain carbon molecules in the fuel mix, increasing their combustibility by lowering their flashpoint and drastically decreasing surface tension of the droplet. HHO gas is not itself all that significant a portion of the fuel in the fuel/air intake stream, then; it is instead an additive which causes a given fuel charge to burn more completely and thus more efficiently. More efficient combustion means greater fuel economy.
It really is just that simple (in the broad strokes), and a properly designed HHO "generator" coupled effectively to the intake system of an IC engine will increase its efficiency, lower its unburned/incompletely burned fuel vapor load in the exhaust stream, and lower the fraction of partially combusted fuel entering the crankcase on each piston cycle.
Simon - I am shocked that you would be posting things like that. While your above paragraphs seems scientifically sound and reasonable, so does this explanation of magnetic fuel savers:
Fuel mainly consists of hydrocarbons. Groupings of hydrocarbons, when flowing through a magnetic field, change their orientations of magnetization in a direction opposite to that of the magnetic field. The molecules of hydrocarbon change their configuration. At the same time intermolecular force is considerably reduced or depressed. These mechanisms are believed to help to disperse oil particles and to become finely divided. In addition, hydrogen ions in fuel and oxygen ions in air or steam are magnetized to form magnetic domains which are believed to assist in atomizing fuel into finer particles.
Generally a liquid or gas fuel used for an internal combustion engine is composed of a set of molecules. Each molecule includes a number of atoms, which is composed of a nucleus and electrons orbiting around their nucleus. The molecules have magnetic moments in themselves, and the rotating electrons cause magnetic phenomena. Thus, positive (+) and negative (-) electric charges exists in the fuel's molecules. For this reason, the fuel particles of the negative and positive electric charges are not split into more minute particles. Accordingly, the fuels are not actively interlocked with oxygen during combustion, thereby causing incomplete combustion. To improve the above, the fuels have been required to be decomposed and ionized. The ionization of the fuel particles is accomplished by the supply of magnetic force from a magnet.
The resultant conditioned fuel / air mixture magnetized burns more completely, producing higher engine output, better fuel economy, more power and most importantly reduces the amount of hydrocarbons, carbon monoxide and oxides of nitrogen in the exhaust. Another benefits if these devices is that magnetically charged fuel molecules with opposite polarities dissolve carbon build-up in carburetor jets, fuel injectors, and combustion chambers help to clean up the engine and maintain the clean condition.
HHO, magnets, acetone are all bunk. There is no "big oil" conspiracy keeping this technology away from us. Just a bunch of P.T. Barnums making an easy buck.