Can anyone tell me the difference between blowoff valves and wastegates. I know both are used to limit turbo lag and also excessive boost, but why one and not the other.

nsanbyker
DIY Pro

 

Wastegates - regulates exhaust pressure going to the turbine of the turbo. Generally, the more exhaust pressure it allows to the turbine, the more boost the turbo can create.

Blow-Off Valves - releases pressure in the the ic piping whenever the throttle plate closes. In general, when you are driving, boost is being generated. When you shift, you usually let off the gas. When this happens, the throttle plate closes, boost slams into the throttle plate coz its closed now and has no where to go except back to the already spinning compressor side of the turbo. This will cause it to slow down or cause it to momentarily stop or momentarily cause the compressor to spin in the other direction.

This results in boost taking longer to build up after you shift. They also say this can cause damage to the turbo.

What a Blow-off Valve does is release or vent the trapped boost pressure into the atmosphere or back into the intake side of the turbo whenever the throttle plate closes, for example in between shifts. This keeps the turbo from slowing down in between shifts.

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G35-Forum.com

 

He's right on the money.

Andrew

2003 coupe 6MT blue premium aero (on order)

 

Thanks for the info. I knew about the blowoffs purpose, and wasn't sure of what the wastegate was for. I thought the wastegate was involved with the exhuast due to the exhaust flange. Now I understand the purpose of both. Makes sense.

nsanbyker
DIY Pro