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Traditionally, heat losses from the turbine are neglected in turbomatching calculations as well as in engine simulations [1]. On the SI-engine, with it's high exhaust temperatures, this assumption will lead to errors in the calculations. Significant amounts of heat are dissipated from the turbine through several mechanisms. This paper contains measurements of the different heat loss mechanisms from the turbine during full load operation on a 4-cylinder SI-engine. The largest loss components are convective and radiative. The heat losses to cooling water and lubrication oil were approximately 3-5% of the total heat loss from the turbine. In addition to heat losses to the surroundings, heat flux is also present internally in the turbocharger. Heat flux from the turbine to the compressor can deteriorate the efficiency of the compressor.

A standardized measurement setup and definition of compressor surge is yet to be established in the automotive community. As a consequence, compressor comparisons with regards to compressor operating map width is practically impossible today. This paper presents a possible solution to the described problem by presenting a suitable instrumentation and a correlation between measured values and actual NVH limits normally encountered in turbocharged vehicle applications. The work has been performed in laboratory conditions in a compressor test rig with both steady and pulsating flow as well as in a gas stand with steady flow. The test rig design, measurement setup and error sources are described. Some effects of different boundary conditions to the compressor and how they affect the measurement method are also presented.