Extension of exhaust manifold conduit into exhaust pipe

Abstract

An exhaust manifold for an internal combustion engine includes a set of exhaust manifold conduits. Pairs of the exhaust manifold conduits converge and are joined at their downstream portions. The pairs of exhaust manifold conduits are connected to associated downstream exhaust pipes. In each pair, a first exhaust manifold conduit having a first downstream portion extends into the exhaust pipe, and a second exhaust manifold conduit having a second downstream portion terminates at the inlet end of the exhaust pipe. A channel is defined by the body of the exhaust pipe and the flat side wall of the first downstream portion. The channel has a cross-sectional configuration approximately the size and shape of the second downstream portion and communicates with the second downstream portion. Each exhaust manifold conduit includes an inner pipe disposed within an outer pipe for reduced thermal dissipation to promote a quicker light-off of the catalytic converter. Extension of the first downstream portion into the exhaust pipe effectively lengthens both the first exhaust manifold conduit and the second exhaust manifold conduit, which increases the engine torque at lower RPMs.