Basically one would take a 4 stroke engine, and at the end of the exhaust stroke, spray water into the cylinder, the water flashes to steam and drives the piston down for another power stroke. The big advantage being the use of the enormous amount of waste heat such engines produce. Carrying it further, one would may be able to reduce (or eliminate!) the size of the present cooling system. Downfalls I see are mainly it's use in cold climates (e.g. one leaves their car outside for a week in sub-zero weather, condensation of water in engine components and exhaust system, etc.).
Anyway I just heard of this and recently stumbled across this web site and put the two together. Apologies if it's been discussed already.
I was thinking about this a bit last night...it could potentially be a hot ticket for reducing GHGs if somebody puts it all together.
One of the technologies people are proposing to combat CO2 emissions is carbon capture and sequestration (CCS). Unfortunately, it's pretty impractical in a personal vehicle -- the CO2 could be trapped in water, but then you'd have to carry around a water mass roughly equivalent to the mass of the vehicle.
Since the 6-stroke already uses water as part of its "fuel", it should be relatively simple to condense the exhaust back into a third tank to capture at least part of the carbon emissions. It should take much less cooling to condense than conventional exhaust, since it's at a lower temperature.
Whether or not carbon can be captured without creating additional emissions from extra energy used to capture it is another issue...I'm not sure how much energy it takes.
I found this website by doing a search for an article I had read online years ago (never found it again). The person writing the article claimed that he had been involved in an experiment to see if 100mpg was possible with an internal comb. engine. To make a long story short , they did , but it took all kinds of engine work , plumbing , water injectors , computer work etc ,etc . They used a Chevy V6 engine and the improvements were all based on leaning the engine as far as they possibly could but this made the engine run very hot (but much more powerful also) . Their solution was to inject distilled water at just the right time to cool the comb. chamber . Downside was that they had to haul around twice as much water as fuel so it wasn't worth it , as well as all of the other expensive mods. Does anyone recognize this story ? I'd like to read it again .