I found this article from David Vizard on gofastnews.com while pulling a red-eye reading marathon several days ago. It is a variation on the familar pentroof head design. I thought you all might be interested. http://www.gofastnews.com/board/technical-articles/281-polyquad-new-four-valve-power-concept.html All that effort and the method to get rid of tumble and replace it with swirl reminded me why the '83-87 twin carb engines work so well. The twin carb setup essentially does the same thing(on the intake side, anyway) in varying degrees at anything below WOT. I think the mild cam timing events these engines have means that less is lost by having a more conventional exhaust valve and port arrangement. Lots of swirl also lends itself to knock resistance and these engines definitely need all they can get. A good example is my father's XL600 compared to my XR600. His has the same compression and stock cam specs as mine and is much less picky about fuel. It would be fun trying the PQ design on an RFVC head and seeing how it responds. Captain Midnight is working on adding quench pads to the chamber....maybe this could be another project. I would have posted in the "Advanced" Technical Discussion forum too, but this topic would just get buried among newbies asking how to clean chains or drain oil.