Abstract: A tangential force internal combustion engine invention utilizes the four cycle internal combustion engine process. Working gas chambers are formed via a torroid in the housing and two adjacent piston assemblies. Pistons, ring seals, and inner seal plate elements seal this chamber. The four gas cycles are spaced over the 360 degree torroid chamber with gas ports appropriately placed. One power vane (PV) and one reaction vane (RV) connect to a central shaft with pistons attached to each vane end. 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 VN 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 operating via three independent but time-coordinated systems. The power vane has no controlled acceleration; combustion pressure serves to immediately couple this vane to the shaft via the OCS.