Abstract
Keywords - Exhaust, Manifold, Flow, Catalyst, Emissions
Abstract - Exhaust hot ends for modern engines need to be developed taking in account various functions and constraints such as engine performance, optimum emission after-treatment, underhood thermal management, durability and, of course, cost. To achieve a fully optimized hot end development, a multi discipline team and several engineering tools, such as in house 0-D models and 3D commercial codes, are required. Particularly durable washcoats are introduced to sustain the high gas temperature at the close coupled converter and still meet emission limits after 100 000 km.
A production intent exhaust hot end developed using the methodology outlined above is here presented. A cast iron exhaust manifold design is discussed including exhaust flow, materiel temperature and stress results. The integration of the catalytic converter welded to the cast iron manifold in the engine compartment are also presented emphasizing the best and most cost effective heat insulation methods to protect the surrounding components. With the help of a particularly durable catalyst, this optimized exhaust hot end allows to reach very low emission limits such as Euro 4 or beyond while minimizing the precious metal usage.