Turbo Anti Lag

As found on WRC rally cars, turbo anti-lag keeps the boost pressure high and the turbocharger spinning by keeping the gas flow high, but maintains drivability by controlling the torque. The gas flow can be achieved by jacking open the throttle with a solenoid, air bypass valves, or if a low level of anti-lag is used, often by opening the idle motor fully. To control torque, the ECU retards the ignition and cuts fuel and sparks.

Boost Control

Boost pressure is regulated by the turbo wastegate which is opened at a boost pressure set by the actuator. To increase boost pressure at which the the wastegate is opened, the actuator needs to see a lower pressure than actually exists in the inlet manifold. The ECU can control a solenoid or air injector to do this. The solenoid or air injector can be turned off / on to give low (actuator level) and high (ECU controlled) boost.