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Turbochargers are used in a wide range of applications, duty cycles and different vehicle usage rates in whole world. As known, the exhaust gas temperature is still a challenge to the turbochargers manufactures once it has a considerable impact in the turbocharger durability and reliability. High temperatures can lead to thermal mechanical stress, which can cause material fatigue. Extensive works have been carried out by product and combustion engineers to guarantee that temperature limits are under acceptable values. However, there are other factors that are related to the application usage in the field that can contribute to the exhaust gas temperature increase. As known, service engineers have the difficult task of identifying the reason why some components used for years in different localities fail only in certain regions, fleet or applications. Trouble shootings are often a useful guide in the investigation, but are to generic most of the cases.

The paper covers the design and development of Heavy-Duty (HD) Diesel engines that meet the 2007 HD US EPA emission standards. These standards are the most stringent standards in the world for on-highway HD diesel engines, and have driven the application of new technologies, which includes: particulate aftertreatment, crankcase ventilation systems, and second generation cooled EGR. The paper emphasizes the importance of designing the product to meet the tough expectations of the trucking industry - for lowest total cost of ownership, lowest operating costs, high uptime, ease of maintenance, high performance and durability. A key objective was that these new low emission engines should meet or exceed the performance, reliability and fuel economy standards set by the products they replace. Additionally, these engines were designed to be fully compatible and emissions compliant with bio-diesel B20 blends that meet the ASTM and EMA fuel standards.

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.