Connecting Rods And Pistons; Cylinder Head And Valvetrain Description; Exhaust Manifolds - BMW 1999-2005 M3 Service Manual

Engine-General
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Connecting rods and pistons

The forged steel connecting rods use
replaceable split-shell bearings at the
crankshaft end and solid bushings at the
piston pin end.
The pistons are of the three-ring type
with two upper compression rings and a
lower one-piece oil scraper ring.
Full-floating piston pins are retained with
circlips.
The 2.8 and 3.0 liter engines use a
graphite coating on the piston skirts to
reduce friction and noise.
Cylinder head and valvetrain
Cooling passages in the cylinder head
are designed for optimum coolant
circulation, allowing the head to operate
at lower temperatures than the cylinder
block.
The aluminum cylinder head uses chain-
driven double overhead camshafts and
four valves per cylinder. The cylinder
head employs a crossflow design for
greater power and efficiency. Intake air
enters the combustion chamber from
one side while exhaust gasses exit from
the other.
Oilways in the head provide lubrication
for the camshafts and valvetrain.
Valve clearance is set by self-adjusting
(zero-lash) hydraulic lifters for reduced
valve noise and the elimination of routine
valve adjustment.

Exhaust manifolds

2/25/2009 9:58 PM