The stock PCV is effective on a relatively stock car. However, once you start pushing over 28 psi roughly you run the risk of damaging the rubber flap inside of it, breaking it. It also can not keep up with hard cornering on cars with tires and suspension. The stock PCV also contributes to carbon build-up
The oil in an inline catch can, such as APR's is from driving the car hard on boost and overloading the stock valve. Because the car is on boost, this oil is sent down to the turbo inlet into a catch can.
Edit - Hard breaking followed by left-hand turns are worse case scenarios for the stock PCV valve. On just Neuspeed springs and Michellin AS/3+ I was able to overload the stock PCV.
If you look at how the 2-way system works, when you're off boost it vents blow-by directly to the intake, bypassing any inline catch can. This is why when people put inline catch cans on they often see very little in them, as for a majority of their driving the blow-by is being directed directly to the valves, rather than the catch can.
This can contribute to carbon build-up, and is the reason people see smoke at the track even with an APR catch can, as when they come off boost and corner hard, the oil is instead sent to the intake valves, completely negating the catch can.
The Audi RS3 LMS car and VWR/Spluuen systems removes this functionality and force it to always vent to the turbo inlet hose. The downside of these systems is that they also delete the yellow passages and as a result, they send more oil down the turbo inlet hose to the catch can when driven hard. AKA there is no longer an oil return passage
They function as an old-school 1-way system. If you just drive the car around normally you will have minimal oil in your catch can. However, when you start flogging it, the PCV will now direct that extra oil that would otherwise be returned to the pan, to the catch can. This is still better than having the stock PCV only direct some to the pan and some to your intake air.
The best solution is to run an actual Air/Oil Separator and plump it back down into the oil pan. This gives you the best of both worlds.
No risk of PCV failure at high boost, oil control at high Gs, no unfiltered blowby into valves. It also returns the excess oil back into the oil pan, like the stock system.
There is a forum post detailing about putting in a setup like this, but IMO it's a bit overkill unless you are heavily tracking the car. I beat on my car really f**king hard ie autocross Watkins glen etc. and only empty my can every 1k miles and it's nowhere near full.
edit - I've been drinking a bit and can't spell
The oil in an inline catch can, such as APR's is from driving the car hard on boost and overloading the stock valve. Because the car is on boost, this oil is sent down to the turbo inlet into a catch can.
Edit - Hard breaking followed by left-hand turns are worse case scenarios for the stock PCV valve. On just Neuspeed springs and Michellin AS/3+ I was able to overload the stock PCV.
If you look at how the 2-way system works, when you're off boost it vents blow-by directly to the intake, bypassing any inline catch can. This is why when people put inline catch cans on they often see very little in them, as for a majority of their driving the blow-by is being directed directly to the valves, rather than the catch can.
This can contribute to carbon build-up, and is the reason people see smoke at the track even with an APR catch can, as when they come off boost and corner hard, the oil is instead sent to the intake valves, completely negating the catch can.
The Audi RS3 LMS car and VWR/Spluuen systems removes this functionality and force it to always vent to the turbo inlet hose. The downside of these systems is that they also delete the yellow passages and as a result, they send more oil down the turbo inlet hose to the catch can when driven hard. AKA there is no longer an oil return passage
They function as an old-school 1-way system. If you just drive the car around normally you will have minimal oil in your catch can. However, when you start flogging it, the PCV will now direct that extra oil that would otherwise be returned to the pan, to the catch can. This is still better than having the stock PCV only direct some to the pan and some to your intake air.
The best solution is to run an actual Air/Oil Separator and plump it back down into the oil pan. This gives you the best of both worlds.
No risk of PCV failure at high boost, oil control at high Gs, no unfiltered blowby into valves. It also returns the excess oil back into the oil pan, like the stock system.
There is a forum post detailing about putting in a setup like this, but IMO it's a bit overkill unless you are heavily tracking the car. I beat on my car really f**king hard ie autocross Watkins glen etc. and only empty my can every 1k miles and it's nowhere near full.
edit - I've been drinking a bit and can't spell
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