New cylinder heads provide better breathing for a gain of 22 horsepower
(16 kW) over the 3.0. Greater torque in the normal driving range accompanies
the power increase -- ninety percent of peak torque is available between
1990 and 5850 rpm. The engine operates on 87 octane unleaded gasoline ("regular"
in the US).
CYLINDER HEAD COVERS
The cylinder head covers are stamped from acoustically damped material
(two sheets of steel surrounding a layer of sound-deadening mastic) to
minimize noise from the valve train. They include integral oil separators.
INTAKE MANIFOLD
The intake manifold consists of a two-piece (upper and lower) aluminum
casting which includes manifold, runners and a plenum. The plenum includes
a curved passage that connects to the throttle body.
EXHAUST MANIFOLD
The compact exhaust manifolds are made of cast nodular-graphite iron
to provide efficient heat resistance. The right manifold is made up of
two pieces bolted together with a metal gasket in between to assure positive
sealing against gas leaks.
The right side manifold handles passage of exhaust gases which
heat the catalytic converter to operating temperature quickly, for low
emissions. The left and right manifolds are connected by a stainless steel
pipe with a bellows to accommodate thermal expansion. The connecting pipe
crosses beneath the engine. Laminated sheet metal covers on both manifolds
provide heat protection.
VALVE TRAIN
There are two intake valves and two exhaust valves per cylinder. The
intake valves are 1.30 inches (33 mm) in diameter. Exhaust valves are 1.14
inches (29 mm) in diameter.
The faces of all valves are finished with carbo-nitriding for long life. Valve guides are made of a cast iron alloy. The valves are driven by rocker arms that pivot on shafts. Rocker arms are die cast aluminum with roller bearing cam followers. Hydraulic lash adjusters, mounted in the valve ends of the rocker arms, provide maintenance-free operation and reduce noise.
The state-of-the-art timing belt is round toothed for durability and
quiet operation. Sprockets are made of sintered iron. A three-piece molded
plastic cover completely encloses the belt and protects it from moisture
and debris damage.
PISTONS AND CONNECTING RODS
The pistons are all aluminum with a shallow crown to save weight. Three
rings are used on each piston: two compression rings and an oil ring. The
top compression ring and the oil ring are chrome plated for durability.
The semi-floating piston pins are pressed into the small end of the connecting rods.
The connecting rods are forged steel with a center distance of 5.55 inches (141 mm). The large end of the connecting rod has an oil-jet hold for intermittent spraying to the thrust side of the cylinder.
The rod bearings, made of a tin-aluminum alloy, are bonded to the back
metal by nickel plating.
CRANKSHAFT
The crankshaft has six throws, four main bearings and five counterweights.
It is made of nodular cast iron. Thrust is taken at the number three main
journal. Stoke is 3 inches (76 mm) Main bearing diameter is 2.36 inches
(60 mm) rod bearing diameter is 1.97 inches (50 mm). Journal tolerances
are close to assure quiet operation and long life.
Crankshaft oil seals are inserted in die-cast aluminum housings which attach to the front and rear of the block. The crankshaft includes a dynamic damper to reduce belt load, torsional vibration and noise.
CAMSHAFTS
Camshafts are made of ductile cast iron. Intake duration is 244 degrees,
exhaust duration is 244 degrees, with 34 degrees of overlap. Lift of the
intake valve is 0.35 inches (8.2 mm). The cam faces are induction hardened
for wear resistance. The distributor is driven direct by the camshaft.
A flange at the rear end of the camshaft acts as a thrust collar. Cam bearing
inserts are not required.
OIL PAN
Like the cylinder head covers, the oil pan is stamped from acoustically
damped steel. The pan is full depth throughout its length, allowing ample
clearance between the crankshaft and the oil to avoid aeration of the oil
it is sealed to the block with RTV. Oil capacity is 4.2 quarts (4.0 liters).
The dipstick is inserted in a guide on the left (forward facing) side of
the oil pan.
OIL PUMP
The pump is a trochoid type, driven directly by the crankshaft for
both reliability and compactness. The die-cast aluminum pump housing contains
the crankshaft oil seal and the oil relief valve and also serves as the
front cover. To protect against aeration of the oil, relief oil is returned
directly to the suction side of the pump. The oil filter is mounted on
the left side of the cylinder block for easy access when service is needed.
FUEL INJECTION SYSTEM
Cast aluminum fuel rails are returnless, thus less complex than customary
systems. High-impedance injectors, with two pintle sprays each, are installed
in each manifold runner.
IGNITION SYSTEM
The distributor is mounted on the rear face of the rear face of the
right cylinder head. A cam-angle sensor is built into the distributor.
The crank angle is signaled by a unique sensor mounted on the transaxle
housing that gets its signal from the transaxle drive plate.
The ignition system supplies power from the coil to fire the plugs at the high speed and combustion pressure the engine demands. The ignition coil is built into the distributor.
COOLING SYSTEM
The water pump is made of cast aluminum and is located at the center
of "V" on the front of the cylinder block. The six-bladed impeller has
a diameter of 3.15 inches (80 mm). It is driven by the back of the timing
belt at .84 times the engine speed. The water pump assembly includes a
conventional shaft, mechanical seals and integrated bearings. Water flows
from the radiator to the pump through a steel pipe in the center of the
"V". From the pump, water is diverted to both banks of the cylinder block.
An inlet side, bypass-type thermostat provides smoother warm-up than a
conventional, outlet side, thermostat and minimizes water pump power requirements.