30psi, breathing heavy on throttle liftoff
 

Why?

the car has a stock breathing system, with an air oil seperator with a sump return but now the boost is turned up its breathing heavily but only on liftoff. During dyno pulls its clean and the exhaust doesnt smell of burnt oil, but it breathes heavily on the liftoff.

Whats happening that Im missing?

Thankyou,
Dann

Im pulling it apart and thinking about it.

Its a recirculating catch can, back into the intake pipe (filter>turbo) instead of VTA filter, and the bottom of the can drains into the turbo drain.


Dann

My car does the same thing after a high boost pull (not as high as yours, somewhere past 20psi on a 2871 churbo) and my separator set up could use some work, and I am seeing some oil on my hotside charge piping. So I am looking at messing around with my separator and adding some sort of baffling, but it is either this, or I have questioned my turbo seals for quite some time. Are you running a one way valve between your PCV and intake manifold? That helped clear up some issues for me quite a bit. The PCV was still allowing some positive pressure to leak into the crank case.

The factory baffles are fairly restrictive, if you're getting that much blow by you will want to start opening up those restrictions both on the exhaust and PVC side. I bypassed the whole PVC system and dumped the enlarged exhaust side vent into a catch can that is open to atmosophere. It's a "racecar" so oil is changed often but even at 1500 mile intervals or once an event the oil stinks of fuel. Keep the PVC valve on a street car. Only reason I do it that way is to eliminate the chance of ingesting oil and causing knock.....and I'm too lazy to build a separator.

When you say "stock breather system" do you mean you still have the crank > intake line with the check valve? And the other side is venting to a catch can that vents into the turbo inlet area?