ATTN: everyone who has a fliter on the valve cover breather - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 12-05-2007, 12:06 PM   #21
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I currently have a diy catch on the PCV side and on the breather side I have it hooked up to a catch with a breather on it. I used to just have it hooked up between the filter and the turbo but I noticed that oil was gettin there and I didnt want that. I have had it like this for a couple of months and havent had any issues. In this pic on the left side you can see my crankcase breather catch.
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Old 12-05-2007, 07:54 PM   #22
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Remember Matt's dyno video? The first time I saw it, I was surprised at how much blowby there was coming out the filter, I thought I could see wisps of smoke, but then I was thinking the exhaust blanket was flapping in the breeze. Sure, it could be leaking past the regular check valve on the other side (I doubled mine up, not sure if this helps, but on a 99 you're in a special situation with a 90* bend to make), but it's not unheard of to pressurize the crankcase under load.

Also, there's pumping losses associated with moving the air back and forth from the inner cyls to the outer under the pistons. I've seen numbers saying it's pretty high but I don't 100% buy into it. They sell big electric pumps for that reason, but anyway... that's why I run my line to the intake of the turbo. That much flow (enough to activate jets on a carburetor) should put some suction on the crankcase.
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Old 12-05-2007, 08:06 PM   #23
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I used to run crankcase evac systems on a bracket racing 67 Firebird and a 92 Mustang for open tracking. Based on data I saw and more experienced advice, I ran them. Anyway, best thing to do all around is to mount a catch can between the PCV and the intake, and a can or filter between the valve cover and turbo. The crankcase will experience negative pressure which is what you want, and if you're running an AFM or MAF the signal won't be screwed up. If you're running a MAP based system then it doesn't matter since there's no airflow signal to be screwed up by an air leak. You can't have one catch can since the PCV system and the other valve cover hose must remain independant of each other.

I run a DIY catch can on the PCV side and a fuel filter on the valve cover to the intake hose before the turbo. If the fuel filter appears to be overwhelmed with oil, I'll install another DIY catch can in that spot.
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Old 12-05-2007, 08:30 PM   #24
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you also forget that video of him sitting there WOT in boost at like 6-7K. (tuning on loaded dyno)

during normal pulls you wouldn't see that, or his manifold starting to glow.
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Old 12-05-2007, 08:37 PM   #25
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Ok, time to ask. It's been bugging me this whole time.

WHY a catch can? So what if you get a little oil in the engine? Won't it just burn off? My guess if you plug the lines with oil, or get build up in the manifold, but I'm curious.

edit:
Heh, My turbo was glowing and glowing last time I had a 6 mile race with a few stoplights with a R6. I wouldn't have been under the hood, but the brakes went out - cooking the master cylender. Ooops.
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Old 12-05-2007, 10:00 PM   #26
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a catch can because:

* oil in your intercooler reduces its effectivenes
* oil in your intake makes a huge mess
* oil in your turbo makes it hard to determine if you have turbo bearing issues
* catch cans look effin cool.
* especially WOT's cheap ones.
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Old 12-05-2007, 10:05 PM   #27
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to prevent this as well:

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Old 12-05-2007, 10:23 PM   #28
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Quote:
Originally Posted by y8s View Post
a catch can because:

* oil in your intercooler reduces its effectivenes
* oil in your intake makes a huge mess
* oil in your turbo makes it hard to determine if you have turbo bearing issues
* catch cans look effin cool.
* especially WOT's cheap ones.
Plus oil creates carbon buildup and promotes detonation. The catch can I use is just a simple DIY setup using PVC pipe, 1.5" diameter and filter media inside to capture the oil mist.
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Old 12-05-2007, 11:22 PM   #29
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Who was the guy that was using a oil filter or a fuel filter that he got at home depot or something.

So whats the consensus right now?

Catch can on the PCV side between PCV and intake manifold

and

Catch can on breather side but connected to a filter instead of pre turbo.

Yes?
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Old 12-06-2007, 12:17 AM   #30
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perhaps you have seen my ancient celica site:
http://www.y8s.com/celica_gone/air-oil/
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Old 12-06-2007, 12:22 AM   #31
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Quote:
Originally Posted by Saml01 View Post
Who was the guy that was using a oil filter or a fuel filter that he got at home depot or something.

So whats the consensus right now?

Catch can on the PCV side between PCV and intake manifold

and

Catch can on breather side but connected to a filter instead of pre turbo.

Yes?

Yes. Thats exactly how I have mine.
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Old 12-06-2007, 12:32 AM   #32
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any pics of this? The second part is difficult to visualize.
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Old 12-06-2007, 02:47 AM   #33
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Sigh.... But I've been putting off the catch can thing FOREVER.

So, Y8s, what do you use now?
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Old 12-06-2007, 04:59 AM   #34
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I have 3 of these right now for $115 shipped each. They are the last ones I will ever have.


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Old 12-06-2007, 09:44 AM   #35
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Quote:
Originally Posted by posidon42 View Post
any pics of this? The second part is difficult to visualize.
Not as pretty as what Wideopentunig has there but it works and shouldnt cost more that $20.




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Old 12-06-2007, 10:05 AM   #36
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Quote:
Originally Posted by Saml01 View Post
Who was the guy that was using a oil filter or a fuel filter that he got at home depot or something.

So whats the consensus right now?

Catch can on the PCV side between PCV and intake manifold

and

Catch can on breather side but connected to a filter instead of pre turbo.

Yes?
I prefer between the breather and intake. You'll get more oil from that inlet than from the pcv valve side, the pcv is only open during cruise, and if you look at all the baffles behind it, it's harder for oil to get through.
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Old 12-06-2007, 10:36 AM   #37
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Quote:
Originally Posted by Braineack View Post
I prefer between the breather and intake. You'll get more oil from that inlet than from the pcv valve side, the pcv is only open during cruise, and if you look at all the baffles behind it, it's harder for oil to get through.
Just so I am clear on one thing. Under normal conditions, with no turbo on an engine, the breather just sucks in fresh air. But with the additional crank case pressure caused by a turbo the breather has the potential to spit oil back into the intake?

I guess the PCV side doesn't make to much sense considering the pressure in the crank case shouldn't be any different at cruise with or without a turbo and if one has a functioning PCV then no oil should pass through it at boost.

The catch can on the PCV side is just a nice insurance policy I think, especially since you don't want oil infused air to be pushed into all the vacuum plumbing. I am curious what is the real answer.

So in reality all a catch can is doing is preventing oil from escaping and making a huge mess.
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Old 12-06-2007, 01:41 PM   #38
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Quote:
Originally Posted by Braineack View Post
I prefer between the breather and intake. You'll get more oil from that inlet than from the pcv valve side, the pcv is only open during cruise, and if you look at all the baffles behind it, it's harder for oil to get through.
I'm with you in my, totally theoretical, never had a catch can world.

One of my other little projects is a turbo diesel, and this thing is under boost at cruise. We've tried this little exhaust check-valve thing I've seen for chevy's... The idea is that it sucks into the exhaust (no worried about oil, then, since it "burns in the exhaust", at least doesn't end up in the intake)... Which might work in a high velocity exhaust, but I can't say I have a strong feeling about it working yet.
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Old 12-06-2007, 01:55 PM   #39
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BTW, Braineack since you mentioned the valve cover. You got a picture of the back of it. What do these baffles that you mention look like?
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Old 12-06-2007, 02:29 PM   #40
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Quote:
Originally Posted by Saml01 View Post
BTW, Braineack since you mentioned the valve cover. You got a picture of the back of it. What do these baffles that you mention look like?



under those plates....
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