Modern diesel engines for vehicular applications such as buses and other commercial vehicles are increasingly using technological resources in order to meet the pollutant emissions regulations. Among these features, the turbocharger fulfills an essential function of providing a higher air flow to the engine intake, providing a cleaner and more efficient combustion.
During the application process of a turbocharger, calculations are performed to estimate the life of the compressor impeller, which takes into account the maximum shaft speed and the number of cycles that cause fatigue damage. Among these parameters, the maximum speed affects directly in the fatigue life of the impeller. Due to the different material options for the compressor impeller, the mass properties of each type of rotor may result in differences in their inertias thus impacting the maximum speed and the fatigue life calculation.
The objective of this study is to provide a comparison of inertias influence for two choices of materials and check the maximum speed behavior with the variation of altitude during experimental tests. The experimental data were gathered in a delivery truck with a GVW of 8 tons, equipped with 4-cylinder engine, while traveling on a route from Guarulhos (ca. 650m alt.) up to Campos de Jordao (ca. 1700m alt.) in the state of Sao Paulo, Brazil.