Abstract: A reinforcement plate for a reciprocating engine that greatly reduces the elastic and plastic deformation of engine block components when the engine is run at high rpm and force is provided which reduces structural fatigue thereby increasing available horsepower. The one piece reinforcement plate ties together the main bearing caps to each other and to the engine block skirt, thereby increasing the rigidity of the main bearing caps and reducing the vibration of the engine. Crankshaft counterweight and crankshaft throw clearance openings, as well as other clearance areas, are provided in the reinforcement plate.