US Patent 11319861 Exhaust conduit with a textured surface

An exhaust system is provided for an automotive engine of vehicles with exhaust conduits having a textured surface. The system comprises a plurality of cylinder exhaust ports, and an exhaust manifold including a plurality of exhaust runners fluidly coupled to the plurality of cylinder exhaust ports, where at least one exhaust runner of the plurality of exhaust runners includes a plurality of steps or dimples protruding outward from the exhaust runner. In one example, the system promotes an effective mixing of oxygen and hydrocarbons in the exhaust stream to reduce engine emissions.