Bi-Turbocharger Switching
A = DIRTY AIR; B = CLEAN AIR; C = CHARGE AIR; D = EXHAUST GASES.
| ITEM | DESCRIPTION |
|---|---|
| 1 | Engine |
| 2 | Exhaust system left intake pipe |
| 3 | Primary turbocharger |
| 4 | Left intake grills |
| 5 | Left air cleaner |
| 6 | Left charge air cooler |
| 7 | Charge air shut-off valve |
| 8 | Charge air recirculation solenoid |
| 9 | Right charge air cooler |
| 10 | Right air cleaner |
| 11 | Right intake grills |
| 12 | Electric throttle |
| 13 | Secondary turbocharger |
| 14 | Exhaust system right intake pipe |
| 15 | Turbine shut-off valve |
When the engine operating parameters approach the limits (approximately 2800 RPM under load) of the primary turbocharger, the ECM begins the switch to parallel bi-turbocharger operation. The secondary turbocharger is brought into operation by the opening of the turbine shut-off valve which allows exhaust gases to flow through the turbine. Fresh air is then drawn through the right air cleaner and the Mass Air Flow and Temperature (MAFT) sensor to the secondary turbocharger compressor.
Initially, the secondary turbocharger does not produce a charge air pressure to equal that of the primary turbocharger. Therefore, the charge air from the secondary turbocharger is fed via the recirculation solenoid into the clean air duct of the primary turbocharger.