[Knuto]

Thank you very much, Sindre!

Its very hard to machine and get valve seats in. Often you need removable valveguides to get the valves in if the valves are set at a large angle. There is an increased risk of cracking in the area where cylinger meats the roof. Thats just naming a few. I think there is little to gain from this very expensive and complicated design. I guess thats why its not used. The american Offy engine used it in the 60s because engines were prone to blow the headgasket at high boost at that time.

EDIT: I atteched some pics from the game I use to simulate the driving. It's free and called Racer.