Intake Air Distribution and Filtering
Intake Air Distribution and Filtering
COMPONENT LOCATION
INTRODUCTION
The intake air distribution and filtering system comprises:
- Dual air intakes, air cleaners and air ducts.
- A supercharger and intake manifolds.
AIR INTAKES, AIR CLEANERS AND AIR DUCTS
Air is supplied to the air cleaners, from under the sides of the hood, through the air intakes, the front fender aprons and the dirty air ducts.
The air cleaners are located in the engine compartment, forward of the suspension housings. Three isolators locate each air cleaner to a bracket on the related front side member and front fender apron. Each air cleaner consists of an air cleaner element installed in a tray and enclosed with a cover secured by six screws. Air inlet and outlet connections are incorporated into the tray and cover respectively. The bottom of the tray incorporates a drain valve to prevent the accumulation of water in the air cleaner. The air outlet connection incorporates a MAFT (mass air flow and temperature) sensor.
Air Cleaner
The clean air convolutes and the clean air duct direct the air from the air cleaners into the electric throttle. Hose clamps connect the clean air convolutes and the clean air duct together, and to the air cleaners and the electric throttle.
The clean air duct also incorporates the following:
- Resonators, to reduce air induction noise.
- A connector stub for the engine full load breather pipe.
The clean air duct is supported by a bracket attached to the RH (right-hand) cylinder head.
SUPERCHARGER AND INTAKE MANIFOLDS
The SC (supercharger) increases the pressure, and thus mass, of the air supplied to the engine, to increase the engine's power output. Two separate intake manifolds direct air from the SC (supercharger) to the cylinder inlet ports.
The intake manifolds are attached to their related cylinder heads and the sides of the SC (supercharger). Two dowels locate the SC (supercharger) in position on the cylinder block. A charge air cooler tank top is installed on top of the SC (supercharger) and intake manifolds to form the air duct from the SC (supercharger) outlet to the intake manifolds. A charge air cooler is installed in each intake manifold.
The charge air cooler tank top incorporates four studs for the attachment of the engine cover. A NVH (noise, vibration and harshness) pad is attached to the side of each intake manifold.
Supercharger and Intake Manifolds - Assembled
Supercharger and Intake Manifolds - Exploded
Supercharger
The SC (supercharger) is a Roots blower with high angle helix rotors driven at 2.1 x engine speed by the secondary belt of the accessory drive.
The two rotors of the SC (supercharger) are contained in a housing. The ends of the rotors are supported in bearings in the front cover and the bearing plate. A rear cover seals the bearing plate and incorporates a filler/level plug for lubricant. A pulley transfers power from the accessory drive to the shaft of one of the rotors.
A pneumatic actuator on the front cover is attached to a by-pass valve in the housing. The bypass valve regulates a flow of air from the outlet of the SC (supercharger) back to the inlet side of the rotors, to control the outlet pressure of the SC (supercharger). Hoses connect the pneumatic actuator to the throttle T-piece of the air ducts, upstream of the electric throttle, and to the front cover, downstream of the electric throttle. A lever connects the actuating rod of the pneumatic actuator to the shaft of the bypass valve. A screw in the front cover limits movement of the lever in the closed direction to allow calibration of the SC (supercharger) output.
The front cover also incorporates:
- The SC (supercharger) air inlet and mounting face for the electric throttle.
- A connector stub for the part load breather.
- A MAP (manifold absolute pressure) sensor.
- A connector stub for a hose from the EVAP (evaporative emission) canister purge valve.
Intake Manifolds
Each intake manifold is attached to the SC (supercharger) with three screws and a bolt. Two dowels ensure correct alignment of each intake manifold. The RHD (right-hand drive) intake manifold incorporates a connection port for the symposer, which, although fitted, is inactive on this vehicle. The LH (left-hand) intake manifold incorporates:
- A connector stub for the brake vacuum system.
- A MAPT (manifold absolute pressure and temperature) sensor.
PRINCIPLES OF OPERATION
Supercharger
At closed or partially open throttle positions, the bypass valve is fully open, allowing a flow of air from the SC (supercharger) outlet back to the inlet side. This results in little or no pressure increase across the SC (supercharger). Progressive opening of the throttle reduces the depression downstream of the electric throttle. This is sensed by the pneumatic actuator, which moves to close the bypass valve. As the bypass valve closes there is a corresponding increase in the outlet pressure from the SC (supercharger), which increases engine power output.