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Old 03-26-2018, 11:46 PM   #1
PrinceVegeta
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Default VTA Head Breathers WITHOUT Catch Can or AOS


VTA Head Breathers WITHOUT Catch Can or AOS

Any thoughts on the way this was setup ?

This was on my buddy's 2007 WRX
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Old 03-27-2018, 06:56 AM   #2
Andrew2166
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Quote:
Originally Posted by PrinceVegeta View Post
https://youtu.be/TiljveQcGgI

VTA Head Breathers WITHOUT Catch Can or AOS

Any thoughts on the way this was setup ?

This was on my buddy's 2007 WRX
Hmm, was wondering if it was possibly.because i ordered an air oil breather/seperator that brings fresh air in...im guessing as long as the corresponding intake holes are plugged, you should have no vacuum leaks or air intake codes...but its pretty much like the older cars that jad little air filters ontop their valve covers to breath, ours just recirc back into intake...i wouldn't leave that open like that do to moisture and possible ran getting in...put like a mini filter on it, and as long as u have no check engine lights should be good
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Old 03-27-2018, 07:50 AM   #3
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I recently built my own AOS catch can system using a cheap baffled catch can and some vacuum tubing. It cost me ~$120 for everything...

Once you understand what all is going on in the PCV system its not that hard to build something yourself. You don't need to spend $400 on the fancy ones...
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Old 03-27-2018, 12:55 PM   #4
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You don't want to do that. Firstly, it's going to blow oil vapor all over the engine bay including the exhaust and turbo, so that's a good fire hazard right there. And it makes a mess.

Secondly, you want the pcv system connected to the intake because it draws vacuum on the crankcase. That increases power by reducing windage losses and improving ring seal. Also, it helps the turbo drain oil back into the case. If you're having trouble with oil going through into the intake, you need a catch can/aos and/or a leakdown test.

I can't see exactly how that is all hooked up, but the pcv lines tie into the turbo inlet so if you have part of that open and part of it connected you have a huge leak of unmetered air
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Old 03-27-2018, 01:25 PM   #5
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VTA breathers work great... if you route them correctly and LEAVE THE BALANCE LINE ALONE.

The only lines you want to vent are the internally baffled PCV lines; some notes:

The port going to the turbo inlet here on the block tee should be rerouted to the front barb on the PCV cross-over pipe (on the intercooler):


Suggested re-routing to remove high load oil vapor in intake (catch can is totally optional, but I would add a hose-end filter as a minimum):



How it looks with the I/C removed (pay attention to black silicone hoses):


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Old 03-27-2018, 01:35 PM   #6
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Now with termination notes:


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Old 03-27-2018, 07:08 PM   #7
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Originally Posted by mrsaturn7085 View Post


This setup appears to pull unmetered air from the catch can to the manifold when pressure is below atmospheric.

And you get no vacuum on the crankcase under load.
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Old 03-27-2018, 09:53 PM   #8
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On the unmetered air point - yes, it does; I've logged identical AFR correction before and after however, therefore the amount is negligible and well within the abilities of the closed loop fueling.

Per my post in an earlier thread:

Quote:
I considered this prior to converting to speed density and logged enough data to see that no fueling adjustments were being made, and no wideband readings changed enough to attribute it to anything beyond a difference in air temp. or similar.

Assuming a functional closed loop fueling algorithm, the window where this unmetered air can have an effect is extremely narrow. Basically, if it's running in CL, the O2 sensors will adjust accordingly (as they do for all changing in pump fueling and aging of emissions components). If it's running in open loop, your PCV is more than likely shut, preventing any unmetered air from entering the manifold. The only time when the factory ECU could not take care of this is the slight transitional time when the PCV is still open and the fueling has changed to OL.
On your second point, what do you think is aiding ring sealing more under load, a slight vacuum on the crankcase or the sharp increase in cylinder pressure acting on the back of the rings?

I love when people try to poke holes in this design (without trying it themselves) as if I'm presenting it as a new idea. This is an exact diagram of the system Prodrive used on their GpN cars until the FIA cracked down on the atmospheric venting in 2008. You remember Prodrive right? The guys that basically built every successful Subaru in motorsport?

I've been using this vented PCV system for literally thousands of miles and have less than a half-quart loss between oil changes at about 95k on the clock; intake is bone-dry as I showed in the KillerB AOS thread before they closed it. You don't like this system? Don't use it... but if you wanna argue about it, you've got a ways to go before you've tested it to the level I have.

Last edited by mrsaturn7085; 03-27-2018 at 10:08 PM.
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Old 03-27-2018, 10:05 PM   #9
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Quote:
Originally Posted by jamal View Post
This setup appears to pull unmetered air from the catch can to the manifold when pressure is below atmospheric.

And you get no vacuum on the crankcase under load.
Truth.

Also:

The filter on the catch can also restricts flow and can allow some pressure to build in the crankcase. While it may be minimal, having the intake tract pulling some away is better than vta with a filter. I'd just run a large catch can between the two case vents and the intake, or one dedicated medium can per case hose. The larger the can, the more vapor will drop out of the air as it slows more passing through a larger can.
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Old 03-29-2018, 05:53 AM   #10
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Thanks guys

Regarding the VTA head breather setup:

So theoretically, isn't it going to be much cheaper if I buy 2 small motorbike air filter and hook it up to the ends of each head breather lines and call it a day?

This way, saves the trouble and money of buying a catch can, and having to T'ee the 2 head breather lines to 1, into the catch can?
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Old 03-29-2018, 01:15 PM   #11
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Quote:
Originally Posted by 2slofouru View Post
Truth.
Well no... the actual truth is reading a data-log that tells you otherwise based on O2 correction. I've explained above how the only point where the small amount of unmetered air makes a difference is during transitional windows of time where the PCV is open and closed loop control is inactive.

Quote:
Originally Posted by 2slofouru View Post

The filter on the catch can also restricts flow and can allow some pressure to build in the crankcase. While it may be minimal, having the intake tract pulling some away is better than vta with a filter. I'd just run a large catch can between the two case vents and the intake, or one dedicated medium can per case hose. The larger the can, the more vapor will drop out of the air as it slows more passing through a larger can.
This is why you read the flow ratings on hose-end filters before slapping one on. It's only going to be restrictive if you choose poorly.
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Old 05-20-2018, 12:59 AM   #12
PrinceVegeta
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Default VTA head breathers and crankcase

Story:

The previous shop that I went to had my dual saikou michi catch cans routed wrongly.

I have since fixed the head breathers as per Mr. Saturns advice by connecting back the balance line back to stock configuration and venting the forward smaller port on the head breathers to atmosphere, as per the video below


The head breathers has been fixed.

Now, I also want to Vent my crankcase port to atmosphere, but Im not sure if that has been routed correctly.

Here is how its being connected right now.



Is this routed correctly?
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Old 05-20-2018, 05:59 AM   #13
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Quote:
Originally Posted by PrinceVegeta View Post
Story:

The previous shop that I went to had my dual saikou michi catch cans routed wrongly.

I have since fixed the head breathers as per Mr. Saturns advice by connecting back the balance line back to stock configuration and venting the forward smaller port on the head breathers to atmosphere, as per the video below

https://youtu.be/WvMYHHfWUjs

The head breathers has been fixed.

Now, I also want to Vent my crankcase port to atmosphere, but Im not sure if that has been routed correctly.

Here is how its being connected right now.



Is this routed correctly?
No, only hose filtered back to intake, is one from the catch can. You want only return lines from your catch can or aos to go back to the intake, so you get the filtered air
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Old 05-20-2018, 09:31 AM   #14
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Thanks,

I plan to disconnect the line from the TEE going to the turbo inlet and

Then cap off the turbo inlet.
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Old 05-20-2018, 02:57 PM   #15
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Here's an image of what I'd recommend based on our phone conversation - note that the block port is a larger hose (IIRC) and I suggest a long hose with a filter fitting on the end on the catch can. Also note the catch can WILL fill quicker since you are collecting low-load vapors as well as the high load stuff; regular draining is required.

Lastly, I know you're running tiny little filters off the heads - this is the way I would route it personally (replace filters with hoses to catch can), to avoid getting your engine bay all oily.

I often refer to my diagram above as the Group N setup... well this is the WRC setup, pretty simple stuff:

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Old 05-22-2018, 01:05 AM   #16
PrinceVegeta
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So I went to the mechanic and got it fixed.


This is how my setup looks like now:





For comparison,

This is how Mishimoto recommends the routing:

https://cdn.mishimoto.com/media/prod...stallGuide.pdf

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Old 05-22-2018, 12:56 PM   #17
mrsaturn7085
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I'm sure you actually did it and just didn't note it on the picture, but be sure to cap the other turbo inlet barb ('forward inlet line').

Also, reusing the block tee and venting EVERYTHING from the original PCV port *might* be choking the line - keep in mind the PCV barb is going to be the least stressed line coming from the block from a mass flow perspective. It makes more sense to cap the PCV side and tap into the original line that went to the intake (high load line). All that said, an even better solution is the original plan - remove the tee and just put a hose right on the block barb.
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