Crankcase Ventilation System Description
A positive crankcase ventilation system is used in order to provide a more complete scavenging of crankcase vapors. Filtered air from the air induction system duct is supplied to the crankcase, mixed with blow-by vapors, and passes through a crankcase ventilation metering device before entering the intake manifold. The primary component in the positive crankcase ventilation (PCV) system is the PCV flow metering device (valve or orifice). Vacuum changes within the intake manifold assembly result in flow variations of the blow-by vapors. If abnormal operating conditions occur, the design of the PCV system permits excessive amounts of blow-by vapors to back flow through the crankcase vent tube and into the engine induction system to be consumed during normal combustion. This engine ventilation system design minimizes oil consumption and significantly reduces the potential for oil ingestion during vehicle limit handling maneuvers.
LT1 Engine
The LT1 engine utilizes an integral positive crankcase ventilation (PCV) system which is located in the Valve Lifter Oil Manifold Assembly (2) beneath the Intake Manifold Assembly (1). The LT1 also utilizes an external PCV separator tank (3). The Valve Lifter Oil Manifold Assembly (2) contains composite oil separating baffles and PCV plumbing. Filtered fresh air is routed from upstream of the throttle plate (4) to the external PCV oil separator tank (3). From there it is passed to both engine rocker arm covers (5) through insulated PCV tubes (6). The rocker arm covers' (6) design incorporates integrated baffles that shield rocker arm oil spray, thereby reducing the potential for oil being drawn back into the PCV separator tank (3) during backflow of the ventilation system. If oil is drawn back into the PCV separator tank (3) it will drain down to the oil pan (7) via an oil drain back tube (8), which further reduces oil consumption. Blow-by vapors are routed from the valve lifter oil manifold assembly (2) through a fixed orifice (7.5 mm) within a steel PCV tube (9), then into the Intake Manifold Assembly (1).