What is a wastegate?

[Phaze1ne]

What is a wastegate and what does it do? And is it mandatory on turbos?

 

[Aikouka]

Wastegates and their respective actuators control the amount of boost that a turbocharger will produce. The job of a wastegate is to control the amount of exhaust gasses that reach the "hot side" of the turbo when the turbo reaches that specified pressure.

So, if your car is set to 8psi ( note, that is is 8 over standard atmospheric pressure of 14psi. ) , when the turbocharger is pressurizing the air at 22psi overall, the wastegate will open to make air go through the exhaust system and bypass the exhaust turbine.

Are they required? Pretty much, unless you want your turbo to produce boost with no limit, which most cars could never handle. Wastegates are there to protect our cars from too much pressure that they cannot handle.

 

[L2RTSiAWD]

The wastegate is a flapper on the turbo exhuast side (internal wastegate).

It's job is at a certain level of boost and actuator on turbo opens the wastegate to allow the excess exhaust gas out. If it did not do this you would technically have no way to limit boost and would be running 40-50-60psi until the turbo and/or motor blows.

P.S. you beat me to it

 

[Aikouka]

As a side note, you may want to read http://auto.howstuffworks.com/turbo1.htm for more information on how exactly a turbocharger works and how each part comes into play.

 

[Defiant]

What is a wastegate and what does it do?

It's a variable "leak" that lets some of the exhaust gas and energy leave the engine without going through the turbine.

And is it mandatory on turbos?

Not always. Some systems have been set up to have characteristics that the turbo can't develop dangerously high levels of boost. However, a turbocharger scheme is a self-energizing situation: as the turbo builds boost, it makes more power, which makes more exhaust energy, which makes more boost and etc.