BLK01S4

engine thats around the valley area. Thats really the only thing that needs to be sucked on to get rida the fumes + valve covers. The thing I plugged works at idle it draws in the oil/vapors from the valve covers into the intake manifold which = BAD. Underboost the checkvalve doesn't allow the air to travel and pressurize the crankcase and valve covers. (Doesnt seal all the way BTW) I removed that connection its not needed as shown in my pic. Ideally you would want to restore that connection with a better check valve to give the gases a sort of direction as Mike2ks4 pointed out. I believe there is enough vaccuum underboost to pull those gases out via Y-pipe, it seems to be working for me as there is evidence in my catch can.

sj6sp

that is what vents the crankcase when the car is running in vacuum. I'd say that is 90% of the time. Don't know what the long term effect of running without the manifold vacuum in the equation...you might want to do an analysis on your oil at the next change interval.

I'm planning to install my catch can essentially in place of the central spider "distributor piece". Crankcase and valve covers feeding into the top of the can. Limiting valve (to YPipe) and check valve (to intake) coming from the side of the can.

Good to know that the check valve leaks, I'll replace it with something a little more stout considering Stage 3 boost.

BLK01S4

Yes I might still install check valve, to lazy right now to do it.