This work is based on experimental studies of gas flow in pipelines of various configurations under conditions of gas dynamic nonstationarity and relates to fundamental studies of gas-dynamic and heat-exchange characteristics of a pulsating flow with an emphasis on the applied part - engine building, as the main industry for the introduction of results. The aim of the work is to refine the physical processes and establish the regularities of the changes in gas-dynamic, consumption and thermal characteristics of processes in the gas-air tracts of piston ICEs from geometric and regime factors under conditions and with allowance for gas dynamic nonstationarity. The complex of developed methods and mathematical models, obtained experimental and analytical data, processed calculation formulas and histograms creates a basis for the development of engineering methods for calculating the intake and exhaust systems of engines, and also expands the theoretical and applied concepts of gas dynamics and local heat transfer of gas streams of the inlet and outlet processes, which is necessary for the modernization of existing and development of new designs of piston engines.