Supercharger: Description and Operation

Engine Supercharger




The 4.0 litre supercharged engine has a throttle body adapter, a supercharger and an intercooler, together with associated ducting, installed between the throttle body and the intake manifold.
Air from the throttle body passes through the throttle body adapter to the supercharger, where it is compressed and directed through ducts to the intercooler. The intercooler extracts some of the heat added to the air during compression. The compressed and cooled air then enters the intake manifold.
A port in the supercharger outlet duct connects with a bypass valve, which bypasses excess compressed air back to the supercharger intake, effectively taking the supercharger off load for a large proportion of the driving cycle.

Throttle Body Adapter




The throttle body adapter provides the interface between the throttle body and the supercharger. It incorporates those components and connections that are installed on the intake manifold of NA engines. Connections for the bypass valve and the actuation pipe of the bypass valve actuator are also incorporated.

Bypass Valve

The bypass valve consists of a butterfly valve contained in an aluminum housing installed between the outlet duct of the supercharger and the throttle body adapter. A bypass valve actuator and a spring are attached to the spindle of the valve.
With a closed or partially open throttle, the vacuum actuator overcomes spring pressure to hold the bypass valve fully open, allowing excess air back to the supercharger intake. As the throttle opens, the depression in the manifold decreases, and the spring progressively overcomes the pull of the vacuum actuator to close the valve, increasing the pressure of the air supplied to the intercooler and intake manifold.

Bypass Valve Actuator

The bypass valve actuator is a vacuum actuator attached to the spindle of the bypass valve. The actuation pipe of the actuator connects to the throttle body adapter at the intake to the supercharger.

Supercharger




The supercharger is a second generation version of the Eaton M90, installed on the front left side of the engine, above the coolant pump. A cast bracket attaches the supercharger to four bosses on the cylinder block.
The belt driven supercharger has a gearbox driving two meshed helix rotors, producing a maximum pressure increase of approximately 0.7 bar (10.2 lbf.in2) at 2750 engine rpm. A seven ribbed belt, driven by the crankshaft, turns the supercharger pulley at 2.5 times engine speed. The supercharger is a sealed unit, with an internal lubrication system.

Intercooler




The intercooler is a fin and tube, air to liquid, heat exchanger integrated into the intake manifold. It cools the air leaving the supercharger to increase the mass of air entering the engine.
For details of the liquid cooling circuit, see Cooling System.

Intake Ducting




A corrugated flexible hose connects the mass air flow sensor to a cast duct attached to the intercooler. The cast duct guides the air rearwards and below the intercooler. A reinforced, corrugated hose connects the downstream end of the cast air duct to the throttle body. A short length of high temperature hose connects an elbow on the supercharger outlet to an elbow on the intercooler intake. 0-rings seal the joints between the cast aluminium elbows and their respective components.