HIGHLY INSULATED EXHAUST MANIFOLD

摘要

An exhaust manifold is provided having a ceramic inner layer defining an exhaust gas passageway, and a composite insulation zone that is highly thermally insulating. In one embodiment, the composite insulation zone includes a plurality of metallic foils in alternating arrangement with layers having insulating qualities. In the composite insulation zone, the layers having insulating qualities can include ceramic layers, evacuated spaces, microsphere layers including substantially evacuated microspheres, or a combination of these. A novel sealing arrangement also is provided for sealing the ceramic inner and metallic outer layers of a metal-encased-ceramic exhaust manifold at a location adjacent the inlet port of a runner of the manifold. A sealing gasket is substantially completely encased within or shielded by the metallic outer layer, so as not to contact the cylinder head when assembled to an internal combustion engine.