An internal combustion engine utilizes the four-cycle process. Gas working chambers are formed using portions of a toroid, two opposing pistons, and seals at the inner gap. A cycle occur over 360 degrees of the toroid with gas ports appropriately placed. One Power Vane (PV) and one Reaction Vane (RV) connect to a central shaft with one piston assembly attached to each end of each vane. The PV produces driving torque on a central shaft through an Overrunning Clutch System (OCS). At specific angles and for controlled durations the PV and RV are slowed, stopped, held to the housing, and then accelerated and coupled to the shaft. Vane movement is controlled by gears, cam ramps, and pin mechanisms operated via multiple, independent but time-coordinated systems. The power vane has no controlled acceleration as combustion forces couple this vane to the shaft via the OCS.