Piston internal combustion engines remain in demand as energy converters for many industries. The improvement of gas exchange processes through the modernization of the exhaust system design is an effective way to improve the performance of a piston engine. The article shows a comparison of gas dynamic and heat exchange characteristics of stationary flows in the exhaust system with profiled channels in the form of a circle, square and triangle. The study was carried out using mathematical modeling and experiments. The statement of the problem, the description of the mathematical model, the composition of the experimental stand, measuring instruments and scientific methods are presented in the article. It is shown that the transverse profiling of channels in the exhaust system has a significant effect on the gas dynamics and heat transfer of stationary air flows. Experiments have shown that the use of profiled channels in the exhaust system reduces the intensity of turbulence by up to 25% and suppresses heat transfer by 10-21% compared to the basic configuration. It is shown that there is a qualitative agreement between the results of mathematical modeling and experimental studies. The obtained data on gas dynamics and heat exchange of flows in the exhaust system are necessary to refine mathematical models and engineering calculations, as well as to find ways to modernize the gas exchange systems of existing and advanced engines. © 2023 Author(s).