Patent ID: 6933056

Claim:
A method of making an exhaust manifold ( 70 ) comprising the steps of: forming a liner ( 12 ) including inner surface ( 14 ) defining manifold passages and an outer surface ( 16 ); forming a first composition ( 76 ) of ceramic powder ( 72 ) and a metal powder ( 74 ); adding a binder ( 78 ) to said first composition ( 76 ) to form a homogeneous material; extruding said homogeneous material through an extruder ( 83 ) to form a feedstock ( 82 ); pelletizing ( 80 ) said homogeneous material to form a feedstock ( 82 ); and molding a shell ( 18 ) of said homogeneous and continuous material of said feedstock ( 82 ) completely encapsulating said outer surface ( 16 ) of said liner ( 12 ).