Check this out. This has such a new concept. Pivotal engine applications - Pivotal Engineering Ltd, Christchurch, New Zealand
While not a pivot engine, here's one involving paired cylinders for increasing efficiency. New Engine Design Sparks Interest - WSJ.com
the only thing that would make your avatar hotter Bear is if they were neckid and lighting thier farts
I think it highly unfair to chastise or otherwise usurp the bear for merely pointing out in a subtle way that this engine might well run on methane. Note too that all safety and aesthetic precautions were taken in depicting this phenomena.