Abstract: A dual wall, air gap exhaust manifold with an integral inlet connecting flange defining an elongated, internal, air injection passageway enclosed by a configurated, convexly bulging cover plate welded over an elongated corner of the flange to form the elongated passageway, the configurated plate being welded over a series of short channels which extend between the elongated passageway and the manifold inlet openings. The elongated passageway has an air inlet connector.

Abstract: An engine exhaust manifold and method of making it, comprising an exhaust port flange having a plurality of exhaust port openings therethrough, a base half shell having a pair of elongated, spaced walls terminating in elongated free ends, a plurality of runners attached to the port flange at the exhaust port openings, a liner half shell having a wall thickness less than that of the base half shell, having a pair of spaced walls terminating in elongated free ends overlapping the base half shell free ends, the liner half shell being oriented opposite the orientation of the base half shell to form a flow passage therebetween, a jacket half shell having a thickness greater than that of the liner half shell, having a pair of spaced elongated walls terminating in elongated free ends, the jacket half shell extending over and encompassing the liner half shell but spaced therefrom to form an airgap therebetween except at the jacket half shell free ends and the liner half shell free ends, the jacket half shell free end

Abstract: A dual wall, air gap exhaust manifold with an integral inlet connecting flange defining an elongated, internal, air injection passageway enclosed by an L-shaped plate welded over an elongated slot in the flange to form the elongated passageway, the L-shaped plate also being welded over a series of short channels which extend between the elongated passageway and the manifold inlet openings. The elongated passageway has an air inlet connector. The spaced dual walls of the manifold runners are joined together at the flange openings, just downstream of the channels.

Abstract: An air gap manifold joint construction of an engine exhaust port flange having a plurality of exhaust port orifices, each with an inner orifice wall, a dual wall manifold having a plurality of runners each including an inner tubular liner and an outer tubular jacket, the inner tubular liner being generally spaced from the outer tubular jacket substantially over the length of the inner tubular liner to form an air gap, the inner tubular liner having an inlet end and the outer tubular jacket having an end adjacent to the inner tubular liner inlet end, said inner tubular liner inlet end having a periphery with an outer diameter substantially the same size as the inner diameter of the outer tubular jacket end and in peripheral engagement therewith, an adapter sleeve having first and second ends, the first end having an outer diameter substantially the same size as the diameter of the inner orifice wall of the exhaust port flange port orifice, and the second end having an outer diameter substantially the same size