PCV system in a Ka24de-t, Does this need to be delt with...

[uvamosk]

So here is my question I might be rehashing something here but I can't find anything by seraching that says that this has been covered. Here is the Problem When we boost a Ka24de the PCV system wasn't made to see boost was it ? and if not then how do we need to reroute our system to handle the increase in postive pressure in the system? I would like to know that I don't large amounts of Pressure building up in a engine that I spent a ton of money on. I have read about turboing engines and the pcv system was something that had to be delt with? If anyone can lay this issue to rest please do so... and we all can live a little happier till someone doesnt use the search button and askes this question again...

[KATwo40]

The stock PCV system in a positive pressure system, meaning that it doesn't suck air from that tube on the valve cover, but rather it's blown in via the venturi effect.

While you don't want boost pressure feeding the valve cover tube, you don't want to just stick an AutoZone mini-breather on it, because you'll be negating the system scavenging created in the block. Basically, it'll allow pressure in the crankcase to build, thus forcing oil blowby out the valve cover and also you might see some smoking out the exhaust.

Make the tube from the valve cover so that it's fed from the airstread PRE-turbo (between the MAF and the compressor housing). The venturi effect will give the scavenging you need to keep the system positive.

Here's a photo of mine:

[david200095367]

Many ppl leave is blank or throw a breather on there and are doing fine.

[get_up_mark]

if i feed into the bov recirculation tube i should prove the same effects as your setup correct?

[KATwo40]

No, because the BOV Recirc. tube doesn't have a constant airflow. It only flows reverse into the intake stream when the valve opens.

The PCV inlet on the valve cover needs a constant, positive pressure airflow. You'd need to have a separate source on the intake pipe.

[uvamosk]

Ok,

So that said I know what your talking about on the postive PCV setup... My second question then would be What about the tube that comes from the PCV valve... can I hook that to the Pipe going into the throttle body? Because I have pluged the small holes that go into the bottom of the Intake Manifold where that pipe and the rubber hoses hooked to it... as saw in the picture I have attached. that pipe and hoses is gone and filled in and smoothed out... But the hose that comes from my PCV valve off the front timing cover ... that hose im going to run to my catch can? and then to my intake pipe before the throttle body?

[9sec240]

The PCV system gets suction from the intake manifold and it draws crankcase gasses thru the PCV valve on the side of the front cover... Filtered air enters the motor thru the top of the tube from the valve cover to the intake tube...

When you boost your motor, your presurizing the intake which forces air backwards thru the PCV valve... Its designed as a one way valve but it does not seal 100%.. This means your pushing air into your crankcase, out the valve cover and thru the tube into your intake piping...

To eliminate this issue, I suggest pulling the PCV distribution manifold off the bottom of the intake and welding the holes shut... unfortunatly this leaves no way to draw air thur the motor and eliminate gasses from the crankcase... On the twins car I ran a braided SS line from the PCV valve to a hole in the frame rail to catch any gasses and vapors and a small K&N breather filter on the valve cover...

I am still working on the ideal solution for the PCV system...

[Ligouri Rd]

What i have heard of other people doing and plan on doing myself is running both the line from the pcv valve and the breather to a catch can. The catch can is then connected to the intake after the maf but before the turbo. That should create a small amount of vacumme to suck any oil mist out of the engine and return any blowby gases to the intake. I am going the cheap route and using a pneumatic oil separator as a catch can (saw someone do this on an S2k). Of course please critique this setup...try not to me too bad.

[KATwo40]

I think you have your vac. direction thinking backward. The tube from the intake pipe (between MAF and Turbo) FEEDS the top of the engine, not the other way around, via venturi effect.

The catchcan is a great idea, however, because when boosting there's a bit of reversion, resulting in oil blowby. The blowby would be contained in the can, while the reverse flowing air (small as it may be) would continue into the intake stream.

[halnfl]

If u run u'r lines the the pipe between ur turbo and mafs the PCV system will work fine even with boost. If u look at the angle of the nipples coming off of the runners going to the seperation pipe u'll notice it isn't a straight up approach, but angled towards the chamber, the reason for this is that when the charge is being drawn into the chamber it creates a slight suction on nipple area. Perfect example: have u ever used compressed air to deflat an inner tube? what u do is hold an air nozzle at a slight upright angle to the valve stem with the valve core out of the stem and the compressed air will deflate the tube. Its the same concept. For more piece of mind u can modify a PCV valve for a 05 Frontier to work in our application, the spring is a higher rate than our orig.

[S13 Charlie]

Hey man,

I don't think you have this right. Seeing as the major flow of air is through the intake tube, the venturi effect would pull air out of the valve cover, not push air into it. you can test this by blowing across a straw in a glass of water, it would pull water up the straw, not push it down.

Or maybe I'm just not understanding it the way you are typing it..