Engine: Description and Operation
ENGINE3.3/3,8L V-6 Engines:
These engines are 60° V type six cylinder power plants with cast iron cylinder blocks and aluminum cylinder heads. Firing order for these engines is 1-2-3-4-5-6. High turbulence cylinder heads allow a 8.9-1 compression ratio.
CRANKSHAFT
The nodular iron crankshaft is supported by four main bearings, with number two being the thrust bearing. Crankshaft end sealing is provided by front and rear rubber seals.
PISTONS
The pistons are cast aluminum alloy. Three rings are used. Piston pins, press fitted into place, join the pistons to forged steel connecting rods.
CAMSHAFT
The nodular iron camshaft is mounted in four steel backed babbitt bearings. A thrust plate located in front of the first bearing, and bolted to the block, controls end play. Silent timing chain drives the camshaft. This chain is enclosed by a cast aluminum cover which also carries a front crankshaft seal, provides front oil pan closure, water pump mounting.
CYLINDER HEADS
Cylinder heads are designed to create high flow combustion chambers to improve performance, while minimizing the change to the burn rate of the chamber. Valve seat and guides are inserts. A steel flanged composition type gasket is used between head and block.
CYLINDER HEAD COVERS
The covers are sealed with steel reinforced silicon rubber gaskets. For NVH improvement, a late introduction of an isolated cylinder head cover will be incorporated. The new cover has rubber isolators at each fastener location.
INTAKE MANIFOLD
The intake manifold is a tuned two-piece semi-permanent mold aluminum casting with individual primary runners leading from a plenum to the cylinders. The manifold is designed to boost torque in the 3600 rpm range and contributes to the engine's broad, flat torque curve, which was desired for excellent engine tractability, response and usable power output.
The intake manifold is also cored with upper level EGR passages for balanced cylinder to cylinder EGR distribution.
VALVE TRAIN
Valve train design incorporates the use of hydraulic roller tappets. Rocker arms are installed on a rocker arm shaft attached to the cylinder head with four bolts and retainers. Viton valve stem seals provide valve sealing. Conventional type pushrods, retainers and valve stem locks are used. Unique beehive style valve spring are used with lightweight retainers for improved high RPM performance.
EXHAUST MANIFOLDS
Exhaust manifolds are log type with a crossover and is attached directly to the cylinder heads.
ENGINE LUBRICATION SYSTEM
Engine Oiling System:
The lubrication system is a full flow filtration pressure feed type. Oil from the oil pan is pumped by a internal gear type oil pump directly coupled to the crankshaft. The pressure is regulated by a relief valve located in the chain case cover. The oil is pumped through an oil filter and feeds a main oil galley. This oil gallery feeds oil under pressure to the main and rod bearings, camshaft bearings. Passages in the cylinder block feed oil to the hydraulic lifters and rocker shaft brackets which feeds the rocker arm pivots.