What is the difference between a wastegate and a blowoff valve in a turbo

civic
honda

#1

What is the difference between a wastegate and a blowoff valve in a turbo? Don’t both of them just release pressure? Can someone please explain to me what the purpose of each one is. Thanks.


#2

A wastegate is on the exhaust side. It allows some exhaust gas to bypass the turbo when the car is producing a lot of exhaust (i.e. high power). This prevents excess exhaust from over-revving the turbo.

A blowoff valve is on the intake side. Its purpose is to vent intake air when too much is being produced to feed to the engine. This typically happens when an engine goes from open throttle, quickly to idle throttle. The inertia and “lag” in the turbo system means that it is still producing enough compressed air for open-throttle operations.