Influence of Sensors and Measurement System Configuration on Mapping and the Use of Turbochargers in the Vehicle

Precisely measured compressor and turbine maps are required for designing the air system of a turbocharged engine. Practical experience, however, often shows significant discrepancies between the maps measured for the same turbocharger with different test setups. Furthermore, the differences between maps measured on a test cell and the conditions prevailing in the vehicle have to be taken into account. This paper discusses some of the causes for these differences. First, the main sources of measurement errors will be identified using a maximum error analysis. Subsequently, several examples will be used to show the influence of different measurement assemblies on the turbocharger maps. Finally, additional factors influencing turbocharger behavior during in-vehicle application will be described.