On the basis of modular pulse converter (MPC) exhaust system the authors present a new swirl exhaust system. Structural parameters on the swirl exhaust system and MPC system for N8160ZC diesel engine were calculated by a mathematical optimum method, and the two systems were tested under the same engine operation for comparison. Experimental results show that the swirl exhaust system has a better engine performance under most of the operating conditions than MPC system, but worse under the low-speed and part-load conditions. In order to understand the mechanism of this swirl exhaust system well, a three-dimensional particle dynamic analyzer (3D-PDA) was utilized to measure the steady turbulent airflow in a swirl three-branched model. The computational fluid dynamics (CFD) code KIVA was modified to simulate the flows. Computational results are in good agreement with measuring ones and reveal the swirl flow behavior in the junction.