Oil Catch Can Question

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just-rust
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Oil Catch Can Question

Post by just-rust » Wed Oct 01, 2014 1:47 am

I have put in an oil catch can and just have a question about the rate this thing should fill. I wasn't expecting very much accumulation in it for a while but after 20 days it was already up and into the viewing tube (Yellow ring in tube is the level):

Image

What is a normal fill period for a catch can?


In my reading I also stumbled upon this which is a huge help for everyone in a colder climate with winter around the corner:

I suggest you take off any catch can in the winter, so it doesn't turn your car into a smoke machine. It has happened to a few people I know. Its only an issue when you get down to the sub zero temps or below. The day it happened to me we had a high of 2° (Originally posted by 93forestpearl)
http://bbs.legacycentral.org/viewtopic.php?f=1&t=37269
Rusty 1991 EJ22T - VF28 - '07 wrx TMIC - MBC - Invidia DP - Walbro 255 SOLD
1992 Legacy SS 5mt, with some neat stuff on it

macipusy
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Re: Oil Catch Can Question

Post by macipusy » Wed Oct 01, 2014 4:06 pm

I can fill mine up in an afternoon. It all depends how much time you spend in boost...that is when you will see the higher crankcase pressures which blow oil into the breathers.
maciek puszynski

01 Impreza | v6 STi RA | 5mt | ej236t
93 Legacy Turbo | TW | 4eat | ej22t
16 WRX | 6mt | fa20
98 Legacy GT | wagon | 5mt | ej25d


2.36L Turbo - RSTi Build

just-rust
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Re: Oil Catch Can Question

Post by just-rust » Wed Oct 01, 2014 5:51 pm

Looks like I am not in boost enough. Rookie mistake! Thanks for the info.
Rusty 1991 EJ22T - VF28 - '07 wrx TMIC - MBC - Invidia DP - Walbro 255 SOLD
1992 Legacy SS 5mt, with some neat stuff on it

macipusy
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Re: Oil Catch Can Question

Post by macipusy » Wed Oct 01, 2014 10:08 pm

Also depends if you route the PCV through the catch can.

Mine is routed separate....so the catch can is only being used in boost, when high vacuum is in the intake, before the turbo. The PCV is seeing vacuum from the manifold during idle, deceleration and cruise conditions.
maciek puszynski

01 Impreza | v6 STi RA | 5mt | ej236t
93 Legacy Turbo | TW | 4eat | ej22t
16 WRX | 6mt | fa20
98 Legacy GT | wagon | 5mt | ej25d


2.36L Turbo - RSTi Build

just-rust
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Re: Oil Catch Can Question

Post by just-rust » Thu Oct 02, 2014 3:22 am

So your catch can is routed off of the intake outlet of the f-pipe and then back into the intake leaving the PCV valve to draw without any reroute to a catch can? I like that idea. If I am following you, it is essentially "recycling" blowby and vapors while not in boost. You aren't needing to collect while in vacuum because they are just being reintroduced to the intake manifold and bypassing the intake/intercooler and saving the mess there.

I read through this thread to understand what you are saying:
http://bbs.legacycentral.org/viewtopic. ... 6&start=75
Rusty 1991 EJ22T - VF28 - '07 wrx TMIC - MBC - Invidia DP - Walbro 255 SOLD
1992 Legacy SS 5mt, with some neat stuff on it

macipusy
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Re: Oil Catch Can Question

Post by macipusy » Thu Oct 02, 2014 4:11 pm

To clarify....PCV valve is in stock steup form. Off the intake manifold to the rear crankcase breather by the turbo.

All other breathers...the rear crankcase, the center crankcase, and both head vents are routed through the catch can and back to the intake elbow, before the turbo.

I am probably seeing some oil coming through the PCV into the manifold and getting burned up in the cylinders...I'm ok with that.

Some oil will jump the gap in the catch can, so there will be a small amount in the TMIC...but the quantity is significantly reduced.

A good thing to do is to convert the catch can to a recirculating type....tap another fitting at the bottom and route it back to the head....all oil captured will then drain back into the motor, allowing you not to have to empty your catch can when it fills up.
maciek puszynski

01 Impreza | v6 STi RA | 5mt | ej236t
93 Legacy Turbo | TW | 4eat | ej22t
16 WRX | 6mt | fa20
98 Legacy GT | wagon | 5mt | ej25d


2.36L Turbo - RSTi Build

just-rust
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Re: Oil Catch Can Question

Post by just-rust » Thu Oct 02, 2014 4:27 pm

I got you. So you must be running this set-up:

Image

Next summer I think I am going to modify my catch can into a three port and try this set-up as well. Good idea with the bottom drain. Will the condensation be a problem draining back into the engine though?
Rusty 1991 EJ22T - VF28 - '07 wrx TMIC - MBC - Invidia DP - Walbro 255 SOLD
1992 Legacy SS 5mt, with some neat stuff on it

macipusy
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Re: Oil Catch Can Question

Post by macipusy » Thu Oct 02, 2014 9:14 pm

Yes, except I'm running the ej205 DOHC heads which only have 1 port on each head.

You can also leave one of each port on the head connected to the center (front) port on the crankcase for pressure equalization, like it is on a stock setup.

As for condensation, it is possible, but most of the water vapors will go through the PCV, since 80% or more time is spent in driving conditions which pull vacuum on the PCV.. I only observed large amounts of condensation when I was running no PCV valve at all, and the water vapor had no where to go except the catch can. Once I reinstalled the PCV system, the moisture buildup in the catch can setup was not noticeable.
maciek puszynski

01 Impreza | v6 STi RA | 5mt | ej236t
93 Legacy Turbo | TW | 4eat | ej22t
16 WRX | 6mt | fa20
98 Legacy GT | wagon | 5mt | ej25d


2.36L Turbo - RSTi Build

just-rust
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Posts: 230
Joined: Thu Dec 26, 2013 4:22 pm
Location: Minnesnowda

Re: Oil Catch Can Question

Post by just-rust » Fri Oct 03, 2014 2:42 am

Thank you for the advice! I am going to experiment with this set-up next spring. I like the idea of leaving the front breathers connected to the crossover pipe. We'll see how ambitious I get though. Supposed to get snow this weekend so I will be pulling the can for the winter now. Snow! WTF Seems a little early. lol
Rusty 1991 EJ22T - VF28 - '07 wrx TMIC - MBC - Invidia DP - Walbro 255 SOLD
1992 Legacy SS 5mt, with some neat stuff on it

Legacy777
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Re: Oil Catch Can Question

Post by Legacy777 » Mon Oct 06, 2014 2:58 am

I experienced bad condensation build up in my catch can which turned things into a milky substance during sub-zero temps. That's the only time I had an issue...and it pretty much filled the can.
Josh

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