Quote:
Originally Posted by Irace86.2.0
So you are saying to not switch to the WRX valve? Why was this valve even suggested? Is it because with FI there is more pressure, so the WRX valve is designed around that pressure level? People suggested to switch why?... does it relieve pressure better with a larger opening or does it have a smaller opening to prevent excessive oil blowby through the PCV system?
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Because WRX valve is designed for boosted engine and can hold higher pressure inside intake manifold from leaking into crankcase while stock valve starts to leak that boost into crankcase. But crankcase starts ventilating more oil with the air that goes into intake manifold with a boosted engine. When the oil catch can is added to avoid that oil going to intake manifold, it is also better to avoid the boost pressure expanding into catch can before being stopped on the PCV side. That is why adding a check valve between the catch can and intake manifold is better than replacing the PCV valve with WRX valve. Since boost is blocked at the exit of intake manifold, check valve reacts quicker. Hope I didn't make this too complicated
Edit: Another benefit is that the oil clogs up the PCV valve mechanism after a while. However, the check valve will experience less oil on the other side of oil catch can.