Internal combustion engine with rifled intake and exhaust manifolds

Abstract

A multi-cylinder internal combustion engine having at least one cylinder head with intake and exhaust ports and having an intake manifold with a common chamber and individual intake runners leading from the common chamber to the intake ports. The individual runners each have interior wall surfaces which are rifled to produce a swirling flow as the intake gases move through the individual intake runners from the common chamber to the intake ports of the cylinder head. This rifling is in the form of a plurality of helical vanes, with the helix being tighter near the intake port than near the common chamber. The helical vanes comprise a first set of helical vanes that extend from adjacent the intake ports to adjacent the common chamber and a second set of helical vanes that extend from adjacent the intake ports to a position intermediate the intake ports and the common chamber. An improved exhaust manifold is also disclosed for use with the internal combustion engine. The improved exhaust manifold includes a common chamber or header and individual exhaust runners extending between the common chamber and the exhaust ports of the cylinder head. The exhaust runners each have an interior wall surface which is rifled to produce a swirling flow of exhaust gases from the exhaust ports through the individual runners of the exhaust manifold to the common chamber of the exhaust manifold.