Does anyone know exactly how a wastegate acutally works?

[justeno_heat]

My friend and I were talking a little while ago about turbos and how they work and I asked him how a wastegate works and we were both stumped because we haven't ever seen or heard of how a wastegate technically works. I was just wondering if anyone could explain.

[thelinja]

Basically it's just a valve that lets exhaust gas bypass the turbine if the boost pressure gets too high.

[Steven]

howstuffworks.com dawg :-)

[msaskin]

There are a few parts; you've got the wastegate itself, the actuator, and the actuator arm.

The wastegate is basically a little flapper door that's part of the exhaust housing of the turbo. When it's closed, the exhaust gas can pass fully around the exhaust housing, spinning the turbine side of the assembly. When it's open, the exhaust gas takes the path of least resistance and flows out the gate, bypassing the turbine wheel, and causing the turbo to slow down. Remeber that the gate is not always fully open/closed, but can be adjusted to partially open/closed, which is how boost is controlled.

The actuator is basically a diaphragm with a spring behind it. The vacuum/boost goes to a nipple on the outside, which in turn pushes against the diaphragm. As the boost builds, it pushes harder on the diaphragm, which in turn moves the actuator rod/arm, which in turn controls the wastegate opening/closing.

Make sense?

~matt