A slide for the high pressure die casting of at least one closed deck engine block having at least one cylinder is disclosed. The slide includes a tool steel portion with reliefs for forming a water jacket surrounding each cylinder. At least one expendable salt core is located in each relief, the salt core having an inner surface and an outer surface with an aperture extending therethrough. The outer surface and inner surface of the salt core is coextensive with an inner surface and outer surface of the tool steel portion. A method for high pressure die casting a closed deck engine block using the disclosed slide and expendable salt cores is also disclosed. The expendable salt cores are separable from the reliefs in the slide, and form bridges or supports across a water jacket to add stiffness and rigidity to the cast engine cylinders.