The engine ventilation system was developed to remove the engine combustion blow-by vapors and minimize the following:
| • | Crankcase pressure build-up |
| • | Oil deterioration |
| • | Oil consumption |
| • | Evaporative exhaust emissions |
During normal idle and part throttle operation, filtered fresh air is routed from upstream of the throttle body blade to the front of the right rocker cover via the fresh air inlet hose.
Blow-by gas in the crankcase valley passes through the oil separator and then flows through the fixed internal flow-restricting orifice.
Via the foul air hose, the blow-by gas is directed from the valley cover right-hand corner to the inlet manifold downstream of the throttle body.
Under heavy load operation and high engine speeds, and acceptable reverse flow condition may occur in the fresh air inlet hose.
During sustained maximum lateral acceleration, the outboard rocker cover may be overloaded with oil. If the blow-by gas is drawn from the rocker cover as in previous design, oil may be ingested into the intake manifold.
The Central Valley Ventilation System is designed to eliminate oil ingestion during severe vehicle cornering maneuvers.
Instead of the blow-by gas being drawn from the rocker cover, a high efficiency oil separator in conjunction with an internal flow-restricting orifice is fitted under the valley cover to draw the blow-by gas from the crankcase.
