Ha, I remember reading about that in university. One of the options my group considered for a culminating project in our engineering degree was a 6-stroke rotary (Wankel) engine that would have a water injection phase after the exhaust was pressed out.

I don't think manufacturing a working model of such a thing would have been within reach for a couple of undergrads, although the project we went with was almost as ambitious— we ended up building a mostly functional laundry washer from scratch.