Exhaust conveying system for internal combustion engines

Claim 1

An exhaust conveying system for internal combustion engines, having an engine head, a single exhaust manifold and a plurality of discrete exhaust pipes connecting the engine head to the single exhaust manifold, each of said exhaust pipe comprising at least a pair of tubular members, one member within the other member, including an outer smooth tubular member and an inner circumferentailly corrugated tubular member, said tubular members having curved sections and rectilinear sections, the corrugations of said inner tubular member extending over the whole circumference of said inner tubular member and the crests of the corrugations being adherent to the surface of the outer tubular member so as to define substantially closed air spaces between said tubular members, with the gaseous fluid contained in said spaces being stationary so as to reduce convection losses, the inner tubular member having corrugations which are closely spaced in proximity to said curved sections and corrugations in proximity to said rectilinear sections which are spaced at greater distances from one another.