since this is a serious talk, i wanted to share something..
well, we (me n my frens in college) have done some performance evaluation to a 4cyl gas engine equipped with HHO generators, and from the test we've done so far it really does help the fc without any power losses..no apparent side effects on the materials, and low emission (since less hydrocarbon fuel used..
however, the test only shows the good effects on low rpm, higher rpm need more supply of hydrogen to achieve the same effect..
its true hydrogen will cause embrittlement to steel due to its higher burning temperature but in this case, the gas is not pure hydrogen..its H202, like the one we got when doing the 'pop' test in high school..even though the combustion temp rise up a bit to around 2500K-3000K, it is still within range as normal combustion temp is around 2000K (i guess forced induction engine also run somewhere around 2500K also)..
the trick of reducing fuel consumption is simple, hydrogen have energy content and its a flammable gas..so when added to gas engine, its helps the combustion process, just like NGV..since burning hydrogen produce H20, then its better than nat.gas which is a hydrocarbon..less CO2 the air we breath (and it use distillised water/air bateri, so its far cheaper)
IMHO, if some of u wanted to install the HHO generators, go on cos its already works..only the long time effect have not been known yet (by me so far)..however, make sure u find someone who really know how to install it since hydrogen is a flammable, odourless, colourless gas..one mistake, then bye bye..
u can find a lot of website that shows how HHO generators work, testimonials, and stuff..but take everything with a pinch of salt..
