Can someone please explain the deal with the diverted valve and wastegate in a turbo system? I keep seeing them listed in upgrade mods but don't get it..... The DVD channels exhaust to spin the turbo and the wastegate keeps pressure from rising in the same system?. Doesn't one defeat the other? Do both need to be changed when you upgrade? If you are looking towards 500-550hp is is necessary? Any simple explanations would be grately appreciated.

 

Diverter valves = bypass valves.

They are used to prevent turbo surge. When your throttle body closes, say... following pressure, all that pressure that was flowing into it has to move back somewhere, so it heads back toward the turbo. If there is nothing to vent it, it will hit the compressor wheel and cause surge. The diverter valves vent or re-circulate this air and prevent your turbo from getting damaged.

A wastegate is used to vent off pressure at a certain point. If you ran a wastegate without a boost controller (996 has a factory one), it would run on whatever the spring is.

The wastegates in 996 turbo systems from the factory are modulated by an actuator. When the solenoid reaches a certain pressure it moves the actuator which uses an arm to crack open the wastegate and vent pressure.

When you upgrade the actuators to 1 bar, they can handle more pressure before cracking open to vent pressure, allowing you to turn up the boost.

 

The upgraded diverter valves are nice because they are typically forced, the diaphragm is metal and not plastic or rubber, which wears over time. The forged ones can also be pulled apart and/or rebuilt fairly easily. factory DV's have to be replaced once they leak.

The 1 bar actuators are good if you want to do 1.2-1.3 bar of boost. If you're aiming for that power level, depending on your setup, it wouldn't be a bad idea.

You don't have to upgrade the diverter valves, but you can buy forged or the upgraded bosch models which are a bit more durable.