and rotor assembly 46 contributing to the reduction of friction losses the spherical piston has a theoretical contact area of zero for each point of contact either with the side walls of the cylinder or the cam surface along the latter the piston is rolling with virtually no friction being developed within the cylinder the dynamics of the movement of a sphere within a cylinder results in the continual displacement of the gasses present with the consequence that a high velocity gas cushion is developed between the sphere and the wall thus direct physical contact between two solids is virtually replaced by a gas interface with the attendant well known reduction in friction forces by dividing the ignited compressed air fuel mixture between two power segments it is possible to obtain a more complete expansion of the products of expansion with a resulting increase in efficiency a further reduction in the frictional forces developed between the spherical piston and the cylinder wall as well as improved sealing can be obtained by resort to the alternative embodiment shown in fig7 a 7b 7c 7d and 7e rotary internal combustion engine 210 is identical to the engine shown in fig1 5 except for the modification of each of the cylinders and the counterpoise sealing system utilized to accommodate each piston engine 210 is provided with a stationary manifold assembly 212 with a cylindrical outer wall 214 around which rotates rotor assembly 216 of which.