Described herein is a turbocharging system comprising a compressor having an air inlet and a compressed air outlet, the compressed air outlet to couple with the intake manifold of the internal combustion engine, a first turbine coupled to the compressor, the compressor driven without using power from the internal combustion engine; and a vacuum compressor coupled directly or indirectly to the first turbine. The first turbine can drive a common drive shaft that includes the compressor and the vacuum compressor or output of the first compressor can drive a second compressor that is coupled with the vacuum compressor. The vacuum compressor can be used to scavenge exhaust from the internal combustion engine.