Exhaust sound pressure level is known to be one of the harmful pollutants. This sound pressure could be reduced sufficiently by means of an exhaust muffler. The design of exhaust muffler is to reduce the sound pressure level, but same time the performance of the engine is hampered by the brake-specific fuel consumption and back pressure of exhaust gases. Similarly, from the operator’s point of view, sound pressure level emanating from the existing 47 hp tractors are having acceptable sound pressure level for providing ease to operator. With a view, a study was taken up to look into effect of the back pressure on the engine performance and development of a new exhaust muffler for reduction of sound pressure level and to provide the comfortable and safer environment to the
operator at ear’s level. The aim of this research was to evaluate the back pressure and afterword validation and theoretical results such as sound pressure level, engine performances of the existing and selected other exhaust mufflers to provide a new design of muffler for better efficiency. Experiment has been carried out with existing exhaust muffler and other six muffler of different tractor under at no load condition, ¼ load condition, ½ load condition, ¾ condition in the laboratory and full load condition. Results revealed that back pressure, fuel consumption, sound pressure level and brake specific fuel consumption values of the existing exhaust muffler varied from 0.79 to 5.99, 0.79 to 6.31, 0.77 to 4.8, 0.41 to 3.2, 1.18 to 6.2, 0.98 to 6.66 and 0.98 to 6.27kPa; 0.72 to 5.52, 0.78 to 5.6, 0.92 to 4.48, 0.76 to 4.8, 1.05 to 5.2, 0.84 to 6.1 and 0.6 to 5.64 l/h;78 to 99, 79 to 99, 81 to 101, 78 to 100, 78 to 98, 77 to 97 and 77 to 98dBA; and 12.71 to 97.48, 13.77 to 98.89, 15.89 to 85.48, 13.42 to 84.76, 18.54 to 91.83, 14.83 to 105.5 and 10.59 to 99.6 g/bhp/h with studied seven mufflers, respectively. The study suggested that interchange ability of exhaust muffler to reduce sound pressure level may advisedly affect engine performance by increasing back pressure and brake specific fuel consumption.