31
Exhaust turbocharger
The exhaust turbocharger in use - a type K16 turbocharger by Borg
Warner Turbo Systems - is characterised by high efficiency over a
wide operating range.
It is large in size – its compressor wheel is 64 millimetres in diame-
ter at the outlet end. At full throttle it can compress 290 litres of
air per second, and it produces relative charge pressures of up to
1.2 bar. Its housing has a separate oil supply.
It is also integrated in the cooling circuit. After an engine stop-
page, the coolant run-on pump V51 dissipates the accumulated
heat.
A sensor-assisted exhaust gas temperature regulation system
ensures that the maximum permissible exhaust temperature of
980 °C is not exceeded in any operating conditions. For this pur-
pose, the exhaust gas temperature sender 1 G235 measures the
exhaust gas temperature in the exhaust turbocharger module
shortly before the turbine wheel (see diagram 451_036 on
page 30).
451_064
Turbocharger divert air valve N249
The turbocharger divert air valve N249 is not located directly at the
turbocharger outlet (see diagram 451_038 on page 29), rather is
attached to the throttle valve body upstream of the throttle valve.
The advantage: after the air recirculation valve opens, the move-
ment of the air is preserved along the relatively long route to the
intake manifold via the intercooler.
Pre-cat oxygen sensor G39
Vacuum actuator for wastegate* control
Charge pressure control solenoid valve
N75
The turbine loses little speed,with the result that the turbo-
charger responds very quickly after the air recirculation valve
closes and the required charge pressure is available.
When the air recirculation valve opens, the air is admitted into the
intake side of the compressor downstream of the air filter via the
circulating-air bypass line (see diagram 451_034 on page 28).
