Systems and methods are provided for a cylinder block having one or more bulkheads. The bulkheads provide a dual-wall structure that may enhance the stiffness of the cylinder block in bending and torsion. The bulkheads may also provide an oil drain to allow oil to directly drain through a hollow core of the bulkhead. An overflow outlet may be formed in an inner wall of a bulkhead. In some implementations, a cylinder block with bulkheads may increase an oil capacity of an engine.