04. Here’s the inside of the left side of the turbo. Here we see the turbine wheel and the other end of the waste gate actuator. As we said earlier, the waste gate controls boost pressure. It opens and closes to maintain or expel exhaust gasses and maintains the turbo- charger’s shaft speed. When pressure can overcome the 8-pound spring, the actuator assembly opens the internal waste gate and anything over 8 pounds of boost is bled out through the exhaust.