A striking feature, that anyone who starts to digress into unconventional research or the free energy area notes, is the immense amount of unstructured information. To get a grasp of the field is rather difficult. In order to assist 'navigation' in the free energy jungle, here are a couple of maps of phenomena and inventions. The maps are by no means complete but, maybe, can help you to get an overview.
Richard Clem's rotational engine
Although I do not have any information on Clem or his device, I would like to comment on the principle of operation, which seems quite simple and straightforward to who has studied the writings of Viktor Schauberger, the Austrian naturalist and inventor.
Indeed Schauberger was working with vortex action in liquids (especially in water) and was finding effects that were at the time, and are still now, unexplainable with the normal principles of physics or thermodynamics.
As far as I understand the engine made by Clem was built around a cone with spiralling channels cut into it and when a liquid, in that particular case vegetable oil, got pressed through the channels, they caused the cone to turn and at a certain point the flow of the liquid and the turning of the cone became self-sustaining, up to the point of putting out a good and heavy (350 HP for a 200 pound engine) power output.
