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The cold end of an exhaust system plays an important role in today’s passenger cars by reducing the engine noise and thus keeping a pleasant cabin room for optimum passenger comfort. However, due to vehicle layout constraints, it may be difficult to achieve a Muffler design which fulfills the required noise attenuation requirement. It becomes imperative to have an understanding of the different parameters that affect the overall tail pipe noise. In an automobile exhaust system, Exhaust Mufflers play a major role in noise reduction by helping in the attenuation of undesirable noises from the engine. The overall content of the tail pipe noise of an IC engine can be segregated into two categories - Order noise and Flow noise. Order noises are low frequency pressure pulses generated during the exhaust valve opening and closing in the engine combustion cycle.

Shielding vehicle underbody or engine room components from exhaust heat is becoming a difficult task with increasing packaging constraints, which lead to the proximity of components with high temperatures of the exhaust systems. Heat insulators are provided to protect various components from exhaust system parts. Generally the requirement of heat insulators are fixed on the basis of benchmarked temperatures measured on vehicles with similar layout, during the initial phase of vehicle design. Also various CFD techniques are available to predict the surface temperatures on components in order to determine the necessity of a heat insulator. The aforementioned techniques use radiation and convection heat transfer effects on a complete vehicle model and the overall process generally takes considerable time to provide the results. This paper deals with a theoretical approach to predict the temperatures on nearby components due to exhaust system heat.

With steep increase in fuel prices, there is a strong need for development of better engines with improved performance and emissions. This needs a dedicated effort on engine hardware optimization for lower CO2 levels. Exhaust muffler design is trade-off between noise, backpressure and size/weight. With increase in exhaust muffler volume and simplification of structure there is a corresponding drop observed in exhaust pressures. Study of such a phenomenon would give an insight to benefits achieved based on changes in muffler volumes/structure. This in a way leads to engine improvement. In this paper it has been shown how exhaust muffler characteristics (size and internal construction) impacts engine performance.