Subaru 2002 Impreza Service Manual page 137

TURBOCHARGER SYSTEM
Intake (Induction)
C: LUBRICATION OF TURBOCHARGER
The turbocharger is lubricated by engine oil branched out from the oil pump. To cope with very
high speed of the turbocharger turbine and the compressor shaft which may reach a maximum
of several hundred thousands of rpm, full-floating type bearings are used which can form ade-
quate oil films on their inside and outside during running.
Further the oil supplied to the turbocharger also plays a role of cooling the turbine so that heat from
exhaust gas does not transmitted to the bearings.
NF0345
(1) Compressor housing
(2) Turbine wheel
(3) Turbine housing
(4) Compressor impeller
D: COOLING OF TURBOCHARGER
The turbocharger unit is cooled by engine coolant, which enhances the reliability and durability
of the unit. The engine coolant from the coolant drain hose located under the cylinder head is led
by a pipe to the coolant passage provided in the turbocharger bearing housing. After cooling the
bearing housing, the engine coolant is led into the coolant filler tank through a pipe.
I N-5