Compressor with secondary boost air outlet passage

A wastegated turbocharger comprises a turbine wheel (5) mounted to a shaft (8) for rotation within a turbine housing (4), which is provided with a wastegate valve assembly 18. A compressor wheel (7) rotatably mounted to the shaft (8) for rotation within a compressor housing (6). A pneumatic wastegate actuator (19) is connected by a boost airline (28) to the compressor intake outlet (15). The compressor housing (6) is provided with a command valve mount (23) for directly mounting a wastegate actuator command valve (22) to the compressor housing. The command valve in use operates to selectively vent the boost airline (28) for controlling operation of the wastegate actuator (19). The compressor housing (6) is provided with a first internal passage (25) communicating between the valve mount (23) and the compressor intake outlet volute (15), and a second internal passage (27) communicating between the valve mount (23) and the compressor intake inlet (14). The first internal passage extends into the outlet volute away from the volute walls.