Subaru 2002 Impreza Service Manual page 158

GENERAL
I
Mechanical
1. General
The engine used in this vehicle is of a horizontally opposed, four-cylinder design. This four-stroke-
cycle, water-cooled, DOHC turbocharged engine uses a total of 16 valves and its main compo-
nents are made of aluminum alloy. It is fueled by a multiple fuel injection system.
The engine's major structural and functional features are as follows:
0
The cylinder head forms pentroof combustion chambers, each having a spark plug located at
its center and two each of intake and exhaust valves (four valves per cylinder). The intake and ex-
haust ports are located in a cross-flow arrangement.
0
A single timing belt drives four camshafts on the left and right banks and the engine coolant
pump on the left bank. Belt tension is automatically adjusted by a belt tension adjuster, eliminating
need for a manual adjustment.
0
The crankshaft is supported by five bearings with high rigidity and strength.
0
The cylinder block is an aluminum die casting fitted with iron die-cast cylinder liners.
(6)
NF0366
(1) Intake camshaft
(2) Intake valve
(3) Piston
(4) Cylinder block
(5) Crankshaft
(6) Connecting rod
(7) Spark plug
(8) Valve rocker cover
(9) Cylinder head
(IO) Oil pan
(1 1 )
Exhaust valve
(1 2 ) Exhaust camshaft
M E-2