Turbo-Charging System Opel Vectra C

General Information

The turbocharger is a Garrett GT 2052S. Its low moveable mass means that it is freely available when accelerating.

The turbo system is set up in such a way that high turbine revolutions are achieved at relatively low engine revs. This means that the engine has a high level of torque at normal rev counts and engine load.

The high torque and the very short, turbo gap mean that the ride is both agile and comfortable.

Lubrication

The turbo shaft rotates at high speed and has been precisely balanced and stored in a sliding bush, which requires a considerable throughflow of oil and allows the shaft to float on a film of oil while rotating.

The oil supply is siphoned off from the oil circulating around the engine. The oil is returned to the engine sump by means of a partly flexible oil return pipe.

Cooling

The turbocharger possess a water cooling system, which enables the temperature in the storage housing to be considerably reduced. Reducing the temperature enables the hazards associated with oil residues and possible consequential damage to be reduced.

The coolant is siphoned off from the cylinder head coolant water outlet. Once the coolant has flowed through the storage housing, it is conducted via the thermostat housing to the engine coolant water inlet.

Ambient Air Valve

The turbocharger (1) creates an excess pressure in the charge air pipe (7), throttle body housing (3) and in the inlet manifold (2). As long as the throttle body is opened, an excess pressure exists on both sides of the ambient air valve membrane (8). When subject to this pressure, the ambient air valve is held closed, partly by the power of the built-in spring, and partly by the excess pressure from the charge air pipe.

When the throttle body closes, the suction effect of the engine quickly creates a vacuum in the inlet manifold, whilst the excess pressure in front of the throttle body is maintained. In order to avoid surges of pressure in the inlet manifold and the bucking that results when the throttle body opens once more, the excess pressure in front of the throttle body must be reduced. In addition, the cumulative excess pressure would slow down the compressor wheel (10) of the turbocharger, thereby leading to poor engine response under load.

The signal cable (6) of the ambient air valve, that under normal load conditions is connected in front of the throttle body, is now connected, with the help of a magnetic valve ambient air control turbine (4), behind the throttle body.

The vacuum in the inlet manifold is conducted via the signal connection to the spring side of the ambient air valve and causes the ambient air valve to open, diverting the excess pressure from the turbocharger and the inlet system back into the inlet pipe (9). Once this has occurred, the turbocharger will give rise to no further pressure in the charge air pipe.

When the throttle body opens once again, no further vacuum exists in the inlet manifold and the connection between the signal cable and the connection in front of the throttle body is restored, in such a way that the ambient air valve closes once again.

Wastegate Valve

The wastegate valve (4) is a regulating valve, that opens or closes the bypass channel (5) adjacent to the turbine wheel (8). A control rod (3) links the wastegate valve to the wastegate dashpot.(2)

The spiral spring incorporated in the wastegate tube works so as to close whilst the pressure channelled onto the membrane by the magnetic valve wastegate (1) via the compressor wheel (7) works in an opening direction.

The magnetic wastegate valve is controlled by the engine management system. The engine management system varies the signal so as to change the extent to which the wastegate valve is opened.

In the event that the pressure exceeds the power of the spring in the membrane tube, the membrane tube control rod begins to move, thus opening the wastegate valve. Part of the exhaust gases is conducted from the exhaust manifold (6) directly into the exhaust system by means of a bypass, thus enabling the turbine revolutions to be regulated.