CYLINDER BORE ISOLATOR CORE FOR CASTING ENGINE CYLINDER BLOCKS

A cylinder block isolator core for use in casting engine cylinder blocks for internal combustion engines. The isolator core cooperates with companion core elements in a casting operation to form a short coolant jacket surrounding the upper portion of each engine cylinder adjacent the air/fuel combustion chamber and an air pocket that surrounds the lower region of the cylinder. Drainback passage core elements may be formed integrally with the isolator core thereby reducing the total number of cores in the casting mold package during a casting operation, the finished casting thereby eliminating dividing walls between the isolator and the oil drain cores thus reducing the number of core elements and reducing the cost and complexity of the casting operation as well as reducing the weight of the finished casting. The isolator core may be used independently of cylinder liners during the casting operation. Alternatively, the isolator core may be used in combination with cylinder liners to simplify the casting operation and to reduce further the total weight of the finished casting by eliminating one cylinder bore wall at the lower region of the cylinder.