Abstract: A water over air intercooler for use in a reciprocating air compressor includes a central core unit having an interior which contains a plurality of air passage tubes, a cooling water inlet and at least one cooling water outlet. A first manifold has at least one air inlet and is in communication with the plurality of air passage tubes so as to receive air from the at least one air inlet and direct the air to the plurality of air passage tubes. A second manifold has an air outlet and is in communication with the plurality of air passage tubes so as to receive air from the plurality of finned air passage tubes and direct the air to the at least one air outlet. The central core unit, the first manifold and the second manifold are integrally connected by welding to form a single piece.