Manifold on an internal combustion engine

Claim 1

A manifold for an internal combustion engine for conducting exhaust gases from the engine to exhaust piping, said manifold comprising: two half shells; each half shell shaped such that when welded to the other half shell pipe lines are defined which lead from each exhaust gas port of the engine, and at least one flat web is defined between said pipe lines; each half shell comprising two steel sheets overlaying one another, at least the sheet to be positioned adjacent the other half shell being comprised of non-scaling steel, and a thin insulating layer of a compressible, heat resistant material between said sheets only in the areas where said pipe lines are to be defined; said half shells and said two steel sheets of each half shell all being welded together along the edges of the pipe lines and at a plurality of points in said web; said pipe lines thereby being comprised of an upper wall portion defined by one half shell and a lower wall portion defined by the other half shell, said web thereby being comprised of flat portions of both half shells welded together at least at their respective edges where said pipes are defined and mutually supporting one another.