Where is my wastegate?
It's part of the turbo. To see it you need to take the catalytic converter off from the side of the turbo. The wastegate is the thing that looks like a big penny. This big penny covers up a hole.
What does the wastegate do?
Essentially the wastegate controls the speed of the turbo and hence your boost pressure. It opens up to redirect some exhaust gases away from the turbo exhaust "fan", (or exducer to sound professional), thus slowing it down.
The turbo spins very fast ~60,000rpm ish - dependant upon boost pressure, flow, type of turbo etc etc...in order to produce pressure and flow.
Exhaust gases pass through the turbo and turn the "fan" in the exhaust side of the turbo, (next to the wastegate). As the revs get higher then more exhaust gases pass through the exhaust and therefore the exhaust "fan" is turned faster which is coupled to the intake fan, and so you make more boost. You make more boost, more air is pushed into the engine and so there are more exhaust gases. More exhaust gases faster spinning exhaust "fan" and intake "fan" and so it goes on. If this was left unchecked then engine and/or turbo damage would result.
To control the speed of the turbo a wastegate is installed. At a certain pressure (~7psi 165 stock pressure) an actuator pushes down on a rod and this opens up the wastegate. i.e. the big penny flips up and reveals a "hole".
|Actuator attached to the turbo||Actuator removed||Pressure hose connections on the top of the actuator||Bottom of the actuator|
Once the wastegate is opened up then exhaust gases can pass through the wastegate and down and out of the exhaust. In essence the gases are bypassing the "fan", causing the turbo to slow down, and hence produce less boost - the turbo is under control.
|The open wastegate (the big penny has flipped up)||The exhaust gas path out through the wastegate and down the exhaust|