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Old 04-27-2010, 07:07 PM   #26
Juks
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Is it a boost leak if you vent it to atmosphere?
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Old 04-27-2010, 08:12 PM   #27
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Ive been thinking about if it could make a difference depending on if some use the older PCV thats in the manifold vs the newer style thats connected to a Y @ the baffled block breather. I know the older style is on the 02-03 wrx and some 04, also was in older EJ in general. The newer style comes in some 04, all of 05+ wrx. All 2.5 turbo engines have the newer style PCV

Reason I ask is because the newer style has one side of the Y that the PCV screws into, and the other goes to the turbo inlet, or catch can if you have one. The side the goes to teh inlet uses a hose about 1/2" diameter. But it has a very small hole to serve as a restriction, its about 3/16" or smaller. No matter how big of a hose you use to vent, you will have this restriction. I assume it is there beacuse air would just flow to the turbo inlet vs through the PCV. "path of least restriction" Should we drill that hole out, or will it fubar how the the PCV is suposed to work? Also if you have it routed to a Catch Can could drilling it out help make any oil that may come up go to the Catch Can vs going through the PCV and into the intake manifold?


Quote:
Originally Posted by dmross View Post
I think it's because a lot of us are/were caught up trying to keep the OEM plumbing (PCV to manifold, vac to turbo inlet) with built motors that run much looser clearances and a lot more boost (blow-by) than the stock system is designed to deal with.

IMHO running a large diameter line the same size as the baffled breather port directly to an oil separator with an inlet of the same size is critical if you are going to block off the central port.

Last edited by rexworx; 04-27-2010 at 08:58 PM.
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Old 04-27-2010, 08:39 PM   #28
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I ran my crankcase hose and t'd it into the valve cover breather. Works like a champ no oil consumption. You can't just put a breather on it it needs to be ran back into the engine or if you boost leak test it it WILL fail
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Old 04-27-2010, 09:08 PM   #29
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Quote:
Originally Posted by shutupnshift04 View Post
I ran my crankcase hose and t'd it into the valve cover breather. Works like a champ no oil consumption. You can't just put a breather on it it needs to be ran back into the engine or if you boost leak test it it WILL fail
You T'd the second block breather to each valve cover? Does your block have stock pistons etc? Do you have any sort of catch can?
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Old 04-27-2010, 10:34 PM   #30
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Here's what the guy who installed my block did:

Ran a 5/8" hose from the PCV to one of the head breathers on the left side, ran another hose from the crankcase hose to one of the head breathers on the right side, then ran hoses from both remaining head breathers (one from each side) to the air/oil separator (IXIZ, two in, one out style) and of course the "out" hose from the A/O sep to the intake. So neither of the crankcase breathers went directly to the catch can, both went to a head breather, then both head breathers went directly to the catch can. There were no T's in the whole system.

Does anyone see any issues with that? I had issues with blow by, but pretty sure it wasn't related to the crank case ventilation system. (scored cylinder walls)
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Old 04-28-2010, 10:23 AM   #31
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So you used 2.5 heads? If so why not just keep it oem. The 2.0 heads have one breather per valve cover. Or your builder put a second set of breathers on the valve covers?

Last edited by rexworx; 04-28-2010 at 11:16 AM.
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Old 04-28-2010, 11:56 AM   #32
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Sorry I got a little off topic there, that was with 2.5 heads. The point was that if you put the second set of breathers on the 2.0 head valve covers, this would be an option. Honestly, I'm not sure why not keep it OEM, I didn't even realize that's what was done until this thread was posted and I had to go look out of curiosity. Not to thread jack, but if there's any reason what I mentioned was inferior to stock it'd be nice to know.
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Old 04-28-2010, 03:04 PM   #33
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hey is there anything wrong with oil going back into the crankcase vent?
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Old 04-28-2010, 05:32 PM   #34
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I don't think so...that's what the crawford A/O sep does.
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Old 04-30-2010, 10:38 AM   #35
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Quote:
Originally Posted by sidewayz View Post
PM's replied

D- I added the correct breather assy for hybrid engines. Since the 2.0 doesn't have the extra main oil breather this is the proper was to configure it to work like the 2.5's



25rtsi- just like the 2.5s
So should I need something like that?
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Old 04-30-2010, 11:26 AM   #36
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Quote:
Originally Posted by rexworx View Post
Ive been thinking about if it could make a difference depending on if some use the older PCV thats in the manifold vs the newer style thats connected to a Y @ the baffled block breather. I know the older style is on the 02-03 wrx and some 04, also was in older EJ in general. The newer style comes in some 04, all of 05+ wrx. All 2.5 turbo engines have the newer style PCV

Reason I ask is because the newer style has one side of the Y that the PCV screws into, and the other goes to the turbo inlet, or catch can if you have one. The side the goes to teh inlet uses a hose about 1/2" diameter. But it has a very small hole to serve as a restriction, its about 3/16" or smaller. No matter how big of a hose you use to vent, you will have this restriction. I assume it is there beacuse air would just flow to the turbo inlet vs through the PCV. "path of least restriction" Should we drill that hole out, or will it fubar how the the PCV is suposed to work? Also if you have it routed to a Catch Can could drilling it out help make any oil that may come up go to the Catch Can vs going through the PCV and into the intake manifold?
I don't use that Y piece at all.

With that Y in an OEM setup, off boost your manifold pulls vac on the crank case through the PCV valve, on boost your turbo inlet pulls vac on the crank case because the PCV valve closes. This setup is "green" because your engine is consuming crank case vapors, and on a stock motor it's fine, because you get minimal blow-by and arguably better ring seal because of vac on the crankcase. Often times, a simple catch can inline with the turbo inlet hose is enough to keep the small amount of oil out of your intake/intercooler tract.

On a built motor pushing +200hp over stock, there is usually a lot more crank case pressure build up. The same setup can pull a ton of oil out of the breathers under boost and the OEM system is likely to be restrictive (Y piece, etc). A catch can that doesn't drain can fill up very fast which is why it is better to use a baffled oil separator. It becomes necessary to allow the crankcase to breath as much as possible to prevent pressure buildup. By getting rid of the Y piece and the PCV system, you lose the benefit of vac on the crank case, however there will be no more oil/blowby gasses entering your intake at any point which is more important on a race motor IMHO.

I tried having the best of both worlds by using a vacuum pump (see thread started by n2xlr8n) after the oil separator to pull vac when off boost, but it ended up being an oily mess with too much unnecessary complexity.

On my car the best result of all the different configurations I tried is the following -

1 large breather line from the large baffled crankcase vent -> 1st port on oil separator
2 large breather lines from each head breather to a T -> 2nd port on oil separator
Oil separator VTA through filter, drain to port on oil pan below oil level

FWIW I use the Element kit, it's pricey but it comes with the proper high-quality lines and fittings and it works very well.

Last edited by dmross; 04-30-2010 at 11:32 AM.
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Old 04-30-2010, 12:30 PM   #37
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Hey dmross, whats the importance of having the drain for the oil separator below the oil level in the pan. I remember the debate a while ago but can't remember the reasoning behind it. Thanks.

KG
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Old 04-30-2010, 12:48 PM   #38
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I've got a custom catch can for my build. I have it with three 5/8" inlets (one from each head and one from the crankcase) and one 3/4" inlet (the large crankcase breather)...

Have it nicely mounted to where the OEM fuel filter sits. I'll have to get pics of it.
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Old 05-02-2010, 10:52 PM   #39
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Quote:
Originally Posted by kellygnsd View Post
Hey dmross, whats the importance of having the drain for the oil separator below the oil level in the pan. I remember the debate a while ago but can't remember the reasoning behind it. Thanks.

KG
A drain line that routes below oil level will be unaffected by crankcase pressure.
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Old 05-31-2010, 10:48 AM   #40
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That part number for the "main breather pipe" doesn't seem to be a valid part number. I found this one on http://opposedforces.com/parts/ 21141AA122 Pipe Water Tank.

Last edited by PSolbergfan; 05-31-2010 at 04:45 PM.
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Old 08-04-2010, 10:46 PM   #41
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I'm glad I found this thread.

I have been chasing an oil consumption issue for weeks now with my hybrid motor. The STI short block is brand new, and I'm using my 02 WRX 2.0L heads. I am consuming oil upwards of a quart every 300 miles. My consumption only seems to happen when I'm under boost, because I don't notice my level dropping at all when I stay out of boost. We have checked compression, spark plugs, turbo, valves, and they all checked out perfect. I get no smoke on start up, idle, cruising, or decel, just some blackish smoke on high boost/WOT. My turbo inlet, throttle body coupler, and intercooler are free of any oil. We noticed oil seepage from my turbo drain pipe and also my main PCV hose coming out of the port on the block, so this leads me to believe that my crank case pressure is too high and blow by is occurring.

As of yesterday, I had this other crank case vent port capped off, as I was instructed to do. I uncapped this port, and it is now T'd off to my GrimmSpeed AOS. However, I still think I need to add an extra port onto each valve head breather like shown in sidewayz post. It's only day 2 of having this vent uncapped and hooked to my AOS. Do you think it would reduce crank case pressure even further if I was to do what sidewayz posted, or should it work how I have it hooked right now?

Does my issue sound like a crank case pressure problem? Like I said, we are at the end of things to check. The car runs great with no problems.

Any help appreciated.
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Old 08-05-2010, 12:10 AM   #42
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why not leave it as is to see what happens first. i think there are a number of us who want to sort this out and figure out the easiest solution to the problem.
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Old 08-05-2010, 08:54 AM   #43
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Quote:
Originally Posted by shutupnshift04 View Post
I ran my crankcase hose and t'd it into the valve cover breather. Works like a champ no oil consumption. You can't just put a breather on it it needs to be ran back into the engine or if you boost leak test it it WILL fail
I'd like to know exactly how this guy ran his... if he T'd it to both valve cover breathers, or just one. Doing it this way would save the hassle of drilling/tapping new vent ports on the heads.
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Old 08-05-2010, 10:59 AM   #44
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Quote:
Originally Posted by PSolbergfan View Post
That part number for the "main breather pipe" doesn't seem to be a valid part number. I found this one on http://opposedforces.com/parts/ 21141AA122 Pipe Water Tank.
ok I updated my post with the correct number.

its 21328aa011
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Old 08-05-2010, 11:13 AM   #45
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No one really answered my question last time...

(1) If you plan to just T the 3 ports together (drill 2 extra vents in heads, T to extra block port), why? The oil return passages will more than adequately do the same thing ("pressure balance"). They are much larger than a 3/4 hose, and there are 2 per head.

(2) If you are going to T them together and run it to a catch can, why? The existing ports allow you to do the same thing, but are baffled and won't expel nearly as much oil vapor since Subaru already designed some "catch can" effect into the block and heads for you.


Please, tell me why I'm wrong.



(I do understand why you would want to open the extra port for 500+whp when you may actually NEED the extra vent release all the blow-by. That isn't what we are talking about here.)
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Old 08-06-2010, 12:52 PM   #46
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sidewayz, what size barbs did you use to tap with? What size are the factory OEM valve breather hoses? 1/2 or 5/8?
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Old 08-06-2010, 04:04 PM   #47
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Quote:
Originally Posted by sidewayz View Post
ok I updated my post with the correct number.

its 21328aa011
This is the wrong part number. This is the coolant pipe that connects the water pump to the oil cooler.
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Old 08-06-2010, 05:40 PM   #48
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I'm in the same boat.....I've got the 2.5 block with CP pistons with 2.0 heads. Initially I ran a standard catch-can setup with the extra crankcase vent tied into the valve cover lines. My can was filling up about every 1,000 miles.

I then installed the crawford AOS. Instead of setting up the two drain ports on the AOS to the Y on the crankcase vent (nearest the turbo), I ran one line to each crankcase vent. I capped off one side of the Y crankcase vent (nearest the turbo).

The rest was per crawford instructions -- inlet on top of the AOS to intake (APS CAI), valve cover breathers T'd and connected to inlet on AOS, and the two lower "drains" from the AOS connected to each crankcase vent. PCV capped.

My oil usage varies, but driving hard or long highway trips can still use 1 qt. per 1,000 miles. No oil in the intake tract.

Do you see anything wrong with the AOS setup I have now? I know the CP pistons have more clearance than stock. Running 21 PSI.
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Old 08-06-2010, 09:56 PM   #49
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I plan on installing a crank case evac system which involves tapping into the downpipes exhaust flow, then connecting this vacuum source provided by the exhaust flow to the crank case port and PCV. Then route the CCV to my valve breathers. With this installed, there is constant vacuum pulling out pressure from the crank case.

I'm hoping this solves my issue!
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Old 08-12-2010, 05:56 PM   #50
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Quote:
Originally Posted by Ryan314 View Post
sidewayz, what size barbs did you use to tap with? What size are the factory OEM valve breather hoses? 1/2 or 5/8?
5/8"

I recently installed a set of valve covers with a second breather bung welded on. Oil consumption seems to be less but I just did it so its really too soon to tell...
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