the prob is crankcase pressure stopping the oil returning and not to much oil going into the head,after a dyno run a couple of years ago on the test run mine through a load of oil out the breathers after turning the boost up,so thinking i'd blew my engine when i got home i did a comp test it was 175psi across the board so it was perfect so after reading posts on numerous forums i decided to use my 30 years of hydraulic experience to use, and looked at how the engine is plumbed up,so basically all i have done is connect the head drain pipe to the turbo drain which is way oversized anyway then the free connection where the head drain used to go run a pipe from that uptp the cam cover and tee into the breather pipes then to the catchcan so therefore it equilizes the crankcase pressure with the pressure in the top of the head then it allows the oil to run back down to the sump,and in the 2 years its been done i have upped the boost twice with mapping sessions with no issues

RRRRB wrote:Alot of different ways to deal with crankcase ventilation.. The only reason you push oil out is because its there to be pushed out to begin with... restrict oil passages as recommended by Tomei. port match all the oil return passages in the block and especially the head.

I have my catch can drain back to the block using the factory spot for the front head drain on RB25, it will also act as a vent.

I make 800whp and run 35psi dont have any issues.. and my motor is far from new..lol