Funktion des "2-Stage Twin Turbo"

System Operation
Single Turbo
Under normal conditions, the ECU control boost and power by the primary wastegate



Sec. Turbo Preparatory Range (Transition state)
When certain condition are met, boost, rpm, throttle and so on, the EGSCVA is opened and the SPRV is open to get the Sec. Turbo up to scratch for smooth transitioning, when it is added to the system. Boost is control by the EGSCVA



Single-to-Twin Turbo Transitional State
This state is achieved when the EGSCVA is fully opened and the SPRV is closed. Once the DPS = 0, it signals the ECU to activate the IACV to open and the Sec. Turbo pressurised air flows to the IC.



Twin Turbo Running
Both turbo's are running, creating pressurised air for the engine. Boost is control using the wastegate.



Twin-to-Single Turbo Transitional State
Once the conditions are met, low throttle, low engine speed and so on, the EGSCVA and the IACV is closed. The primary still remains functionable and boost is control by the wastegate.

SPRV - Supercharge Pressure Relief Valve
Used to relief pressurise air to Atmos. in the Sec. Turbo during preparatory startup, for smooth transistioning

IACV - Intake Air Control Vavle
Controls Sec. Turbo Pressurises air to the IC.
Either close or open
Closed during Single Turbo and During Sec. Turbo preparatory start-up

ABV - Air Bypass valve
AKA BOV-recirculated

DPS - Differential Pressure Sensor
Sense the difference in Pressure
Used to optimally switch from a single turbo to Twin turbo. When sec.turbo preparatory pressure equal the primary turbo pressure, it signals the ecu to go twin-turbo, by opening the IACV to allow air into the IC.

EGSCVA - Exhaust Gas Supply Control Actuator
Valve that supply exhaust gas to the Sec. Turbo Turbine
Controlled by EGSCVA Duty Selenoid, EGSCVA Valve Selenoid (Positive Pressure Selenoid) and EGSCVA Valve Selenoid (Negative Pressure Selenoid)

VT - Vacuum Tank
Stores Negative Pressures created by the Intake Manifold when it is in a negative pressure stated.
Used to supply negative pressure to control the IACV, SPRV, EGSCVA.