Turbo-Lag Measurement on a Hot Gas Test Stand

Engine downsizing has been widely used by the automotive industry to lower engine emissions. In conjunction with engine downsizing, turbocharging is typically used to provide equivalent power output to the previous large capacity engines. However, turbocharging is typically criticized due to the inevitable turbo-lag. In this paper, the experimental approach adopted to measure turbo-lag as performed on the University of Malta Hot Gas Test Stand is detailed. The turbo-lag measurement was stemmed from experimental research aimed at utilizing compressed air injection into the compressor housing to impinge on the compressor blades and therefore spool up the turbocharger (i.e. similar to impulse turbine). The focus in this paper is how this Hot Gas Test Stand provided an extremely beneficial method to measure turbo-lag without the complications and interactions of an accompanying internal combustion engine. Furthermore it was found that the turbo-lag measurements can be done on this test stand without firing up the combustion chamber, i.e. using more air flow in lieu of high temperature, was found to be adequate to provide representative turbocharger operation.