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Crankcase Ventilation System Description (LT4)
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 supercharger. The primary component in the positive crankcase
ventilation (PCV) system is the PCV flow metering device (valve or orifice) . Vacuum changes within the supercharger 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. There are three clean air supply locations for
PCV. Two on the right side valve cover and one on the left side valve cover. See Figure 1
Fig. 1
3 Clean air supply locations for PCV
PCV hose 12645127 can be purchased to obtain the quick connect fitting, when creating a custom installation (item 1 in
figure 2)
Fig. 2
Variable Camshaft Timing
This engine has the ability to vary the camshaft position versus the piston position. If you chose to use the Chevrolet
Performance engine controller kit, then it will vary camshaft timing to improve emission and fuel economy, while still
producing great power. At idle, for example, the cam is at the full advanced position, allowing exceptionally smooth idling.
Under other conditions, the phaser adjusts to deliver optimal valve timing for performance, drivability and fuel economy. At
high rpm it may retard timing to maximize airflow through the engine and increase horsepower. At low rpm it can advance
timing to increase torque. Under a light load, it can retard timing at all engine speeds to improve fuel economy. A vane-type
phaser is installed on the front of the camshaft to change its angular orientation relative to the sprocket, thereby adjusting the
timing of valve operation on the fly. It is a dual-equal cam phasing system that adjusts camshaft timing at the same rate for
both intake and exhaust valves. The system allows linear delivery of torque, with near-peak levels over a broad rpm range,
and high specific output (horsepower per liter of displacement) without sacrificing overall engine response, or drivability. It
also provides another effective tool for controlling exhaust emissions.
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LT4 Engine Installation
IR 12AU15
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