Thread: Crank Case Ventilation fully explained. (Turbocharged edition.)

You missunderstood what I said about that hose. That's your idle hose, and it sees boost even on a stock DET. Assuming you have a draw-through MAF setup or are using MAP+IAT then you're still okay. Overkill I guess, but still okay.

If you have a blow-through MAF setup, you're now in trouble.

I'm sorry if I did not clarify, It's a SR20DE+T.

Which is why I thought I should route it down so it only ever saw vacuum.

And I am blow thru, I just recently changed all my piping and moved my maf up to 10" away from Throttle body. Have I pooched my car somehow, it seems fine?

Blow-through MAFs prevent anyone and everyone from recirculating blow-by properly into the intake. If you do, oil coats the MAF element and you'll get poor readings and decreased life from the sensor. If you're going to stay blow-through, I would not recirculate the crank case ventilation. You're better off just venting it to atmosphere. Better yet, go back to draw-through for the MAF so you can do things properly.

As for your idle hose situation, DET or DE+T doesn't matter. The idle valve can see boost, it's fine. What you've done now is allow the idle valve to ingest air that hasn't been metered by the MAF yet, so the ECU has no idea how much air the engine is getting at idle and has no idea how much fuel to inject. The fact that you say your engine seems fine is a bit surprising to me. I'd have expected idle to be very rough.

If it's working for you, maybe not worry about it.

Ahh damit... ok, I will correct it all

Hi guys!

I'm the new guy from Finland. I need help from you your opinion about my sr20det engine crank case breath setup i have couple pictures what i have planned and what i had last summer when i drive my new engine break-in. So here is first picture what i planned to do! tell your opinion is this wrong or right? -: crank case gases to valve cover T-piece, i removed T-piece and planning weld an10 fitting to replace it and then I'm planning to weld two an10 fitting both side of valve cover (FIRST PICTURE) and purpose is to link them together and attach them to the exhaust pipe using E-vac scavenger set.

problem i had dyno and my daily driving the problem is that the is the engine is panting ( breathing, under heavy acceleration ) it raises oil from crank case pipe to catch can not much but too much for me i know this system sucks... i want to improve crank case breathing.

About the engine: fully build: cp pistons, forged rods, acl race bearings, arp bolts everywhere, cometic gaskets, hks ecu engine uses map, engine outputs 478//577 E85 1,32bar horse//torque

Thanks and sorry for my bad english hope you guys understand ! peace and love

@jannn Can you better describe the problem you're having that you are trying to solve with these modifications? I'm not sure you need to do any of this.

thanks for answered @BenFenner. The problem is pressure (hard acceleration) in crankcase which throws engine oil to catch can i had also slightly overfill which improved this. i'm trying lower crankcase pressure as much i can near to the vacuum using e-vac scavenger setup. Picture what @saad posted
would this setup work properly but if I connect valve cover (welded an10 as picture) to the exhaust pipe? not to the air filter side. I am also increasing the boost pressure next summer near to 2,0bar i just want to make sure that the crankcase to breathe correctly and won't strangle i want hear your opinion.


I hope you get what i mean! thanks

You could perform the modifications you've suggested and it may help some, but when you add ports to the valve cover you should use care to make sure the ports are baffled enough upstream to stop oil from just sloshing into the exhaust and causing a lot of oil loss.

If you run the stock setup with the self-draining oil separators, there is no catch can to fill up.

I tried the exhaust method with little success. I ended up using a hybrid valve cover (S13 SR front section welded onto an S14 valve cover) plumbed into my intake directly with no oil catch can at all, and everything is bone dry. I also have CP pistons and I run 20psi (1.36 bar). It's a very simple, clean, and effective way to do it. I also have a very healthy motor though (for now, ha ha); so I may put a catch can in eventually between the intake and valve cover as a precautionary action.

This is my current setup, and it works awesome.

Thanks you guys @BenFenner @2_Liter_Turbo.

I did a quick few pictures. First is very "vacuum" setup.. too big vacuum is not good either is that possible picture 1 setup?
I will try to weld the plates different levels in the catch tank so engine oil does not get out of tank and turbo, if i'm going to connect to the air filter side


Or something like this? this would be very similar @2_Liter_Turbo with

I try to get peace of mind