Variable Geometry Turbine (VGT) Turbocharger - Primary
| ITEM | DESCRIPTION |
|---|---|
| 1 | Charge air outlet |
| 2 | Exhaust inlet |
| 3 | Exhaust outlet |
| 4 | Oil feed connection |
| 5 | Coolant return connection |
| 6 | Coolant supply connection |
| 7 | Variable Geometry Turbine (VGT) vane actuator rod |
| 8 | Oil return connection |
| 9 | Variable Geometry Turbine (VGT) vane actuator |
| 10 | Clean air inlet |
The primary turbocharger is attached to the left exhaust manifold and secured to 3 studs on a flange on the manifold with nuts. On production, no gasket is used to seal the joint surface between the turbocharger and the manifold. In-service vehicles will require a service gasket to be fitted if the joint surface is disturbed.
A second flange on the turbocharger provides for the attachment of the left down pipe of the exhaust system. Three screws secure the down pipe to the flange and a gasket seals the joint.
The compressor end of the turbocharger has two hose connections. The central hose connection provides a clean air supply from the air cleaner to the compressor. The second connection on the outside of the housing provides for the attachment of the charge air ducts.
The turbocharger comprises a turbine wheel and a machined compressor wheel, sharing a common shaft which is supported on ball bearings. The application of the machined compressor wheel and the ball bearing results improved durability reduced Noise, Vibration and Harshness (NVH) and optimized fuel economy. The turbocharger receives an engine oil feed via a pipe from the cylinder block. The pipe supplies the turbocharger with engine oil for lubrication purposes. An oil drain pipe from the turbocharger allows oil to drain from the turbocharger into the cylinder block. The turbocharger has a connection for the engine cooling circuit to provide the appropriate cooling efficiency of the ball bearing.
An integral bracket houses the VGT vane actuator. The VGT vane actuator is connected to an eccentric lever which moves the turbine housing to adjust the position of the vanes. When the actuator operates a boss is rotated, which in turn moves the lever and changes rotary motion into linear motion. The lever is connected to a rod attached to the outside of the turbine housing and the linear motion is converted back to rotary motion of the housing.
Operation of the VGT vane actuator is controlled by the ECM. The VGT vane actuator also provides the ECM with a feedback signal to determine the pitch angle of the vanes.
The variable vanes in the turbocharger improve the exhaust gas power transfer to the turbine wheel which in turn drives the compressor wheel. This greatly assists the increase in charge air pressure at low engine speeds.