Possible mutation ( Background http://www.pivotalengine.com/gallery.html)
Pivot piston little modification. Using in four-stroke “piston “ square valve.
One big advantage have “piston Pivot”. Pistons not have force: Nm !!!
This reaction is only in bearing piston !!
Another, piston no need lubrication, lubrication only need “Rings” (sliding seals)
Next my modification: sliding seals put no in piston. This seals put in cylinder!!
Advantages: cylinder are LIFETIME, my by building only aluminum cast.
Because on cylinder no sliding piston and seals, made aluminum, excellent conduct heat !!
But piston must make steel cast. (Or steel surface)
Then piston and seals only need change at refit engine, without any mechanical enginery.
Theoretical, only need to change part to repair engine!
In this version lubrications are need only seals, sure much little in conventional piston.
Ma-by using conventional popped valve too.
Background animation: http://www.pivotalengine.com/solutions.html#animation
Are you like square pistons now ??
http://www.new4stroke.com/images/33.htm need http://www.edrawingsviewer.com/
Full animation Half Rotate Engine , or Vane-piston :
Regards Andrew Feliks