Variable Geometry Turbine (VGT) - Turbocharger

WARNING: This page is about a different variant/trim than selected.

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

ITEM	DESCRIPTION
1	Exhaust gas outlet to exhaust system
2	Exhaust gas inlet from exhaust manifold
3	Coolant outlet
4	Oil pressure supply from cylinder block
5	Vane actuator
6	Clean air inlet
7	Charge air outlet
8	Coolant feed from cylinder block
9	Oil feed connection
10	Oil return connection
11	Coolant connections
12	Vane actuator rod

The Variable Geometry Turbine (VGT) - turbocharger is mounted to the left (bank 2) exhaust manifold.

NOTE: On production vehicles, no gasket is used to seal the joint surface between the turbocharger and the exhaust manifold. In-service vehicles require a service gasket to be fitted if the joint is disturbed.

The turbocharger consists of two main elements, a turbine wheel and compressor wheel, enclosed separately in cast housings and mounted on a common shaft rotating on two ball bearing races. The ball bearings receive an engine oil feed for lubrication from an outlet at the rear of the engine block, oil then returns to the engine oil pan via an oil drain pipe. Gen 2 engines also have a coolant feed to the primary turbocharger housing from the engine cooling system.

An integral bracket on the compressor side of the turbocharger locates the VGT vane actuator. The VGT vane actuator is connected to an actuator rod which moves the turbine housing to adjust the position of the vanes. When the VGT vane actuator operates, a lever is rotated by a lever arm, which in turn moves the actuator rod and changes rotary motion into linear motion. The actuator rod is connected to a second lever arm attached to the outside of the turbine housing. The linear motion is converted back to rotary motion of the housing and adjusts the variable vanes within the VGT.

The VGT has a connection for the engine cooling circuit to provide the appropriate cooling efficiency of the ball bearing races.

The Powertrain Control Module (PCM) controls the output to the vane actuator motor using a Pulse Width Modulation (PWM) signal. The VGT vane actuator also provides the PCM with a positional feedback signal to determine the pitch angle of the vanes. An angular position sensor in the motor is provided with a 5V reference voltage from the PCM. The position sensor returns a ground and a signal voltage proportional to the actuator position.

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.