Abstract: An automotive reciprocating engine design is disclosed preferably including an extruded cylinder bore block with cylinder bores and a surrounding coolant passage extending from a top flat surface to a bottom flat surface; a cast, closed bottom, open top crankcase with vertical walls having flat upper surfaces; and a stamped metal mid-plate interposed in sealing relationship between the bottom surface of the cylinder block and the flat top surfaces of the crankcase. The crankcase contains bearing supports for a crankshaft and the mid-plate contains holes for connecting rods attached to pistons in the cylinder bores. The design facilitates low cost manufacture of strong, light weight components and easier assembly of the engine, and permits flexible manufacture of a family of engines with different displacements by substitution of a cylinder block of different length or of different bore diameter.

Abstract: An automotive reciprocating engine design is disclosed preferably including an extruded cylinder bore block with cylinder bores and a surrounding coolant passage extending from a top flat surface to a bottom flat surface; a cast, closed bottom, open top crankcase with vertical walls having flat upper surfaces; and a stamped metal mid-plate interposed in sealing relationship between the bottom surface of the cylinder block and the flat top surfaces of the crankcase. The crankcase contains bearing supports for a crankshaft and the mid-plate contains holes for connecting rods attached to pistons in the cylinder bores. The design facilitates low cost manufacture of strong, light weight components and easier assembly of the engine, and permits flexible manufacture of a family of engines with different displacements by substitution of a cylinder block of different length or of different bore diameter.