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In this paper the performance of a new EGR cooler with double efficiency capabilities is presented. This device allows for temperature modulation between the actual cooled and non-cooled EGR temperature. The cooler has a double circuit in its interior controlled by a valve. The outer dimensions of the cooler remain the same as current fixed geometry coolers. The prototype has been characterized on test flow and thermal efficiency rigs and also tested on the engine test bed. Tests show that for steady partial load conditions little benefits may be achieved in CO and HC emissions with a small increase of NOx emissions. More promising results have been obtained during engine warm-up tests in which significant reductions of HC and CO are attained with low increases of NOx emissions. This shows a potential to reduce CO and HC emissions which are mostly generated during the first stages in the emission certification test in Europe.

On actual gasoline turbocharged engines it is common to use a compressor by-pass valve in order to solve the compressor surge problem when the throttle pedal position is released and closes rapidly. The paper deals with a methodology based on experiments to measure the discharge coefficient of an integrated compressor by-pass valve, to understand the possible difference between the steady flow test bench and turbocharger test bench discharge coefficient measurements. To determine if there is some compressor outlet flow field influence due to compressor blades rotation that could modify the discharge coefficient measurement, compared to the steady flow test bench measurements, a fully instrumented turbocharger was used to measure the difference between steady flow test bench and turbocharger test bench discharge coefficients results. Effects of different boundary conditions on turbocharger test bench tests and how they affect the discharge coefficient measurement are also presented.