one engine subassembly perhaps subassembly 6 was present the side forces 27 and 28 would tend to rotate the engine as torque is taken off its crankshaft to drive the vehicle and this rotative tendency would have to be counteracted by the engine mounts however due to the presence of engine subassembly 5 rotating in an opposite direction on the same timing the side forces 27 and 29 are counteracted by equal and opposite side forces 26 and 28 since the pistons are timed identically and the crankshafts counter rotate the pair of forces 26 and 27 and the pair 28 and 29 are always equal in magnitude and opposite in direction throughout all portions of the combustion cycle because the two engine subassemblies 5 6 on which the force pairs act are connected as a unit by braces 3 and 4 or other connecting means the force pairs cancel each other and cannot result in movement of the engine thereby relieving the engine mounts of such forces each of the cylinders 38 40 42 and 44 has a head portion in which an igniting device 46 inlet valve 48 a fuel injector 46 and an exhaust valve 50 are mounted and provide their conventional functions due to the nature of the combustion cycle cyclic variations in torque on the crankshafts may still exist however work may be performed by the crankshafts by mounting a fluid power pump or electric generator or other power take off device entirely and directly to.