Engine Component Description

Crankcase Ventilation System Description

A closed crankcase ventilation system is used in order to provide a more complete scavenging of crankcase vapors. Fresh air from the throttle body is supplied to the crankcase, mixed with the blow-by vapors and then passed through a crankcase ventilation valve and into the intake manifold. The primary component in the positive crankcase ventilation (PCV) system is the PC\( valve, the valve meters the flow of blow-by vapors at a certain rate depending on manifold vacuum. To maintain idle quality, the PCV valve restricts the vapor flow when manifold vacuum is high. If abnormal operating conditions arise, the PCV system is designed to allow excessive amounts of blow-by vapors to back flow through the crankcase vent tube and into the engine air inlet to be consumed be normal combustion. The engine ventilation system was developed to minimize oil consumption and ensure that oil ingestion could not occur during vehicle limit handling maneuvers.


LS1 Engine
On the LS1 engine, filtered fresh air is routed from up stream of the throttle blade to the front of the right valve rocker arm cover through a formed rubber hose. To reduce the potential of oil pullover into the throttle bore area due to back flow of the ventilation system; the fitting in the right side rocker cover is shielded from the rocker arms and their oil spray. Blow-by vapors are routed from the rear of both rocker covers, through molded nylon lines to a tee fitting located on the centerline of the engine at the rear of the intake manifold. From there, a single nylon line carries the vapors through an externally mounted, horizontal PCV valve and enters the intake manifold behind the throttle body.

The dual draw PCV system was developed to meet the limited handling maneuver requirements. During sustained passively lateral accelerations, the outboard cover may fill with oil. The dual draw system passively switches, allowing the PCV valve to draw on the rocker cover with the least resistance. This results in the system drawing on the air filled, or inboard rocker cover and eliminates oil pullover due to drawing on the oil filled outboard rocker cover. The PCV valve is connected to the PCV valve pipe. The PCV valve pipe is attached to the coolant air bleed pipe by a cable with an integral fastener. This cable transfers heat to the PCV valve to eliminate condensation build-up in the PCV system. This also aids in eliminating throttle body icing.


LS6 Engine
The LS6 engine utilizes an integral PCV system. The PCV system is moved into the engine's valley. The valley cover has composite oil separating baffles and PCV plumbing incorporated. The filtered fresh air is routed from up stream of the throttle blade to the front of the right valve rocker arm cover through a formed rubber hose. To reduce the potential of oil pullover into the throttle bore area due to back flow of the ventilation system; the fitting in the right side rocker cover is shielded from the rocker arms and their oil spray. Blow-by vapors are routed from the valley cover, through a formed rubber hose that carries the vapors through an externally mounted, horizontal PCV valve and enters the intake manifold behind the throttle body.


Drive Belt System Description

The drive belt system consists of the following components:

^ The drive belt

^ The drive belt tensioner

^ The drive belt idler pulley

^ The crankshaft balancer pulley

^ The accessory drive component mounting brackets

^ The accessory drive components

- The power steering pump, if belt driven

- The generator

- The A/C compressor, if equipped

- The engine cooling fan, if belt driven

- The water pump, if belt driven

- The vacuum pump, if equipped

- The air compressor, if equipped

The drive belt system may use 1 belt or 2 belts. The drive belt is thin so that it can bend backwards and has several ribs to match the grooves in the pulleys. There also may be a V-belt style belt used to drive certain accessory drive components. The drive belts are made of different types of rubbers chloroprene or EPDM - and have different layers or plys containing either fiber cloth or cords for reinforcement.

Both sides of the drive belt may be used to drive the different accessory drive components. When the back side of the drive belt is used to drive a pulley, the pulley is smooth.

The drive belt is pulled by the crankshaft balancer pulley across the accessory drive component pulleys. The spring loaded drive belt tensioner keeps constant tension on the drive belt to prevent the drive belt from slipping. The drive belt tensioner arm will move when loads are applied to the drive belt by the accessory drive components and the crankshaft. The drive belt system may have an idler pulley, which is used to add wrap to the adjacent pulleys. Some systems use an idler pulley in place of an accessory drive component when the vehicle is not equipped with the accessory.


LS1/LS6 Engine





The 5.7 Liter V-8 engine is identified as RPO-LS1 (VIN-G) and RPO-LS6 (VIN-S).

Camshaft and Drive System
A billet steel 1-piece camshaft is supported by 5 bearings pressed into the engine block. The camshaft has a machined camshaft sensor reluctor ring incorporated between the fourth and fifth bearing journals. The camshaft timing sprocket is mounted to the front of the camshaft and is driven by the crankshaft sprocket through the camshaft timing chain. The crankshaft sprocket is splined and drives the oil pump driven gear. A retaining plate mounted to the front of the engine block maintains camshaft location.

Crankshaft
The crankshaft is cast nodular iron. The crankshaft is supported by 5 crankshaft bearings. The bearings are retained by crankshaft bearing caps, which are machined with the engine block for the proper alignment and clearance. The crankshaft journals are undercut and rolled. The center main journal is the thrust journal. A crankshaft position reluctor ring is mounted at the rear of the crankshaft. The reluctor ring is not serviceable separately.

Cylinder Heads
The cylinder head assemblies are cast aluminum and have pressed in place powdered metal valve guides and valve seats. Passages for the vapor ventilation system are at the front of each cylinder head. There are no exhaust gas passages within the cylinder head. Valve rocker arm covers are retained to the cylinder head by 4 center mounted rocker arm cover bolts.

Engine Block
The engine block is a cam-in-block deep skirt 90 degree V configuration with 5 crankshaft bearing caps. The engine block is aluminum with cast in place iron cylinder bore liners. The 5 crankshaft bearing caps each have 4 vertical M10 and 2 horizontal M8 mounting bolts. The camshaft is supported by 5 camshaft bearings pressed into the block.

Exhaust Manifolds
The exhaust manifolds are a 1-piece cast iron design. The exhaust manifolds direct exhaust gasses from the combustion chambers to the exhaust system. Each manifold has a single inlet for the Air Injection Reaction (AIR) system and an externally mounted heat shield retained by bolts.

Intake Manifold
The IAFM or integrated air fuel module is a one piece composite design that incorporates metal threaded inserts for mounting the fuel rail and throttle body. The intake manifold is sealed to the cylinder heads by eight separate nonreusable silicone sealing gaskets which press into the grooves of the intake housing. The drive by wire throttle body assembly bolts to the front of the intake manifold. The throttle body is sealed to the intake manifold by an one piece push in place silicone gasket. The fuel rail assembly with eight separate fuel injectors is retained to the intake by four bolts. The injectors are seated in their individual manifold bores with O-ring seals to provide sealing. A fuel rail stop bracket is retained at the rear of the left fuel rail by the intake manifold mounting bolts. A snap fit Manifold Absolute Pressure (MAP) sensor housing is mounted at the rear of the manifold and sealed by an O-ring seal. The MAP sensor is installed and retained to the MAP sensor housing. There are no coolant passages within the intake manifold.

Oil Pan
The structural 2-piece oil pan assembly has cast aluminum upper and lower halves. Incorporated into the upper oil pan design is the oil filter mounting boss, oil level sensor mounting bore, and a non-removable oil pan baffle. The oil pan cover, oil temperature sensor, and oil level sensor mount to the sides of the upper oil pan. Incorporated into the lower oil pan design is the drain plug opening and internal oil control ribbing. A nylon carrier with a silicone bead type gasket provides sealing between the upper and lower halves of the oil pan assembly. The alignment of the structural oil pan assembly to the rear of the engine block and transmission housing is critical.

Piston and Connecting Rod Assemblies
The pistons are cast aluminum. The pistons use two compression rings and one oil control ring assembly. The piston is a low friction, lightweight design with a flat top and barrel shaped skirt. The piston pins are chromium steel. They have a floating fit in the piston and are retained by a press fit in the connecting rod. The connecting rods are powdered metal. The connecting rods are fractured at the connecting rod journal and then machined for the proper clearance.

Valve Rocker Arm Cover Assemblies
The valve rocker arm covers are cast aluminum and use a pre-molded silicone gasket for sealing. Mounted to each rocker cover is an ignition coil and bracket assembly. Incorporated into the covers are the oil fill tube, the Positive Crankcase Ventilation (PCV) system passages, and the engine fresh air passages.
Valve Train Motion is transmitted from the camshaft through the hydraulic roller valve lifters and tubular pushrods to the roller type rocker arms. The valve lifter guides position and retain the valve lifters. The valve rocker arms for each bank of cylinders are mounted on pedestals or pivot supports. Each rocker arm is retained on the pivot support and cylinder head by a bolt. Valve lash is net build. For the LS6 application, both the intake and exhaust valves are of a hollow stem design. The exhaust valve stem is sodium filled for improved cooling.

Valve Train
Motion is transmitted from the camshaft through the hydraulic roller valve lifters and tubular pushrods to the roller type rocker arms. The valve lifter guides position and retain the valve lifters. The valve rocker arms for each bank of cylinders are mounted on pedestals or pivot supports. Each rocker arm is retained on the pivot support and cylinder head by a bolt. Valve lash is net build. For the LS6 application, both the intake and exhaust valves are of a hollow stem design. The exhaust valve stem is sodium filled for improved cooling.