 With series twincharging, the turbocharger can be of a less expensive and more durable journal bearing variety, and the sacrifice in boost response is more than made up for by the instant-on nature of displacement superchargers.While the weight and cost of the supercharger assembly are always a factor, the inefficiency and power consumption of the supercharger is almost totally eliminated as the turbocharger reaches operating rpm and the supercharger is effectively disconnected by the bypass valve.Parallel arrangements typically require the use of a bypass or diverted valve to allow one or both compressors to feed the engine.