Positive Crankcase Evacuation Explained

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supra33202
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redhb240SXS13 wrote:So WD, what your suggesting is to run the stock PCV valve to a check valve, out of the check valve to a catch can/ oil separator, and back into the four ports on the bottom of the upper intake mani? I heard people plug those holes because they are a common boost leak nuiscense. If thats the case where would you suggest returning the air back into the system at?

I may be completely off on this, still getting a grip on this PCV business.
Actually, I have the same question.

So WD, what's your opinion on removing the PCV system and plug those holes in regards to the risk of boost leak?

http://www.ka-t.org/forums/vie...f5ca7


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WDRacing
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Every vacuum line is a potential boost leak. Just replace the lines and use tie straps or even a drop of super glue.

Or just lose the PCV system entirely like I described above. Worrying about a "possible" boost leak isn't worth not having crankcase evacuation. Don't believe anyone that says different, they simply don't understand.

WD

supra33202
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Hopefully, kouki_hmongster or other people can show us some pictures for their improved PCV system setup. It would clear alot of things.

WD, thanks for your input.

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So have you completed your setup yet? I am wanting to go hunt for a pump in the 'yard but wondered which one you went with.

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neverlift
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this should be sticky as hell wd

I have pics somewhere of the last time I cleaned mine, it was a tar like substance that smelled like burnt fuel and oil nasty as f***.

I know it works better cause I had the line kinked due to a hasty engine install, my oil lasted only 1500ish miles before I felt the NEED to change it....500 mile mark normally the oil has turned and it now stays that golden color longer.

Glad a thread with research and info has landed, dont let it fall off the front page maybe people will find it

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It's already in the sticky homegirl I did contemplate sticking this thread all by itself. I think this topic slips 90% of most DIY guys minds during a project

WD

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neverlift
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girlfriend you dont even know how long I went with my vc just ota as well as the pcv :barf

supra33202
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Any pictures after the installation?


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neverlift
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its real simple actually, I just got some hose and an oil/air seporator from one of may favorite tuning shops(harbor freight ) then run one end of hose to the stock pcv and the other to the 4:1 tee coming off the manifold cut it where you want to place your separator, if you get the one like me use a small bolt and hose to keep it from being a vac leak.

It does have some flaws to it, but it gets the job done.it has ups and downs. The thing has no filter which was a plus when I cleaned it ,a little dawn in both sides ,rub a little and its sparkly clean again. But the design is to let the oil drip out of the bottom, fine and dandy on a air line for tools and what not but not so hot as its a vac leak, thats when you put the plug on.The leak is minute but there as you can hear a clear hiss unless its blocked..

I'll go snap a shot, I didnt clean it with my last oil change so it should be dirty still.

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Dirty is good because it'll show how much oil/carbon would have ended up INSIDE the intake manifold otherwise. Put steel wool inside the seperator to assist in removing the oil from the air. I'd come up with a valve or something for the hole in the bottom. Any leak is a bad thing IMO.

eclypse
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the simplicity/effectiveness of steel wool in the separator is awesome. kinda ghetto, but i really dont see why that wouldnt work fine.

more expensive catch cans have baffle systems, which would work BETTER, but you're talking $2 here.. i love it

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neverlift
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WDRacing wrote:Dirty is good because it'll show how much oil/carbon would have ended up INSIDE the intake manifold otherwise. Put steel wool inside the seperator to assist in removing the oil from the air. I'd come up with a valve or something for the hole in the bottom. Any leak is a bad thing IMO.
agreed, I honestly dont recall the last time I've seen steel wool in a store, I'll look for it finest I can get I'd assume?

yeah I about broke my cam on this, the stupid regular batteries are good for one or two shots with or without flashok got two in before total shut down. they suck and my hose I had blocking the vac leak was letting most of it drain off to the ground.

note this particular piece(cheapest one from harbor freight) has a filter already that WAS white and is now black. hope this helps wd.

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MTX450
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In responce to this thread, I think what you have done here is great. I'm sure you have seen the mess of a thread that is on KA-T.org regarding this subject. I have compared our KA design in the FSM against the SR20DET's ventilation system to see the differences they made as well. I am still a little confused on how and why the check valve is used. Is it used as replacement of the stock PCV valve? Or is it used with it? Could a catch can be used instead of the oil air separator? Or will the catch can not completely remove the oil moisture from the airflow? A diagram would be awesome, but I'm keeping my mouth shut, haha.

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silverkaturbo
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It was mentioned earlier you can use the valve as either a replacement or add it in line. WD suggested in line. But Im with you MTX on not understanding why. If the stock pcv is already a check valve, how does adding another check valve flowing the same direction change anything? What is the difference in design between the stock valve and that buick gnx valve?

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The stock valve isn't designed to keep out boost pressure. Adding in a second check valve simply doubles your safety. I'm going to use 2, it's to easy and cheap not to

The catch can is ok if you fill it with steel wool or something similar, it gives the oil something to adhere to as the air passes through.

My winter build will have 100's of pics. Everything required to install a budget turbo kit with explanations and pics and diagrams etc. My goal is to make it as complete as possible.

I'll pay particular attention to the crankcase evac part, to include part numbers and where to buy everything. Picture the bestest build thread ever and you're almost there

WD

supra33202
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WDRacing wrote:The stock valve isn't designed to keep out boost pressure. Adding in a second check valve simply doubles your safety. I'm going to use 2, it's to easy and cheap not to

The catch can is ok if you fill it with steel wool or something similar, it gives the oil something to adhere to as the air passes through.

My winter build will have 100's of pics. Everything required to install a budget turbo kit with explanations and pics and diagrams etc. My goal is to make it as complete as possible.

I'll pay particular attention to the crankcase evac part, to include part numbers and where to buy everything. Picture the bestest build thread ever and you're almost there

WD
Cool. I am looking forward to your winter build thread. :D

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silverkaturbo
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WDRacing wrote:The stock valve isn't designed to keep out boost pressure. Adding in a second check valve simply doubles your safety. I'm going to use 2, it's to easy and cheap not to

The catch can is ok if you fill it with steel wool or something similar, it gives the oil something to adhere to as the air passes through.

My winter build will have 100's of pics. Everything required to install a budget turbo kit with explanations and pics and diagrams etc. My goal is to make it as complete as possible.

I'll pay particular attention to the crankcase evac part, to include part numbers and where to buy everything. Picture the bestest build thread ever and you're almost there

WD
That sounds awesome. Like a one stop, step by step sticky instead of having to fish through all of them. Just curious what is the basic setup gonna be? Turbo, top or bottom, engine management?

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silverkaturbo wrote:
That sounds awesome. Like a one stop, step by step sticky instead of having to fish through all of them. Just curious what is the basic setup gonna be? Turbo, top or bottom, engine management?
Well things got interesting budget wise yesterday. A portion of my monthly income was removed causing me to rethink my build. I may be building something repeatable so I can sell a 240SX fuel managment system. We'll see what happens in the next few days. I may start WDRACING after all

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robbie2009
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Do you still leave the valve cover vented? If so, I'm taking this as I could run a line from the PCV valve on the block to a air/oil separator then to a vacuum port on my intake manifold(custom manifold for turbo build), would that work?
Modified by robbie2009 at 6:59 PM 10/13/2009

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robbie2009 wrote:Do you still leave the valve cover vented? If so, I'm taking this as I could run a line from the PCV valve on the block to a air/oil separator then to a vacuum port on my intake manifold(custom manifold for turbo build), would that work?
Yup, that'll do


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robbie2009
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Now if instead of using the intake manifold for vacuum; say I use the vacuum pump. Do I install the line to pcv valve and then to a air/oil separator and then to the electric pump then to atmosphere?

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Yes that would work. You may not need the PCV inline between the pump and separator, but it won't hurt and it makes for a simple connection. If you do use a pump, make sure the separator is actually working and make sure that you clean it often. You don't want oil reaching the pump.

I'm leaning towards a header mounted system along with the standard intake manifold vacuum. That way I don't have any current draw from the pump, nor the hassle of mounting/wiring it. That way I can still have on-boost evacuation when it's needed most and still have something that works at idle/cruise.

WD

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neverlift
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just commenting back on the need of some sort of drain valve, I blocked the air oil separator off and the thing just pushes open under boost ,I assume ,and sprays the bs all over the place. Its very nasty stuff, may try to mod it later this week so that a drain valve is installed. I dont believe the piece I am using is designed for vac and boost.

so wd you are saying you will run an exhaust type evac?

are you gonna use a kit or just cut a pipe at an angle and run a hose to it?

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Summit has a kit for under $50. Comes with everything you need and it's made by smarter people then me...lol.

I dunno why your seperator is leaking, why not JB that whore closed?

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neverlift
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how its deigned is the only reason I can come up with. Plus it came from harbor freight

no I am gonna slap a radiator pet c*** in that whore

Bigsyke
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I skimed through this article, and I like the way you regurgitated every PCV article on the web.

VTA doesnt affect your oil. This has been proven with UOA's and has actually helped on cars known to sludge issues even after a 5k UOA. The oil will get hot enough to burn off any moisture/contaminants as long as your not running a nismo tstat in the winter.

The only way to pull vacuum is with a pump.

How consistant is a exhaust slash cut? I have seen a user report positive pressure throughout load changes with a chambered muffler.

The OEM PCV valve doesnt put negative vacuum on your crank case. The crankcase is almost always in positive pressure, and the PCV valve is forced open. The idle manifold vacuum pulls it open, but it doesnt pull vapors, it meets the vapors at the valve.

Hook a vac gauge up to a pcv valve with a 3/8ths female fitting, and tell me how much vacuum does the valve allow? Now can that effectively out flow a 7/16ths opening on the opposing side where the fresh air comes in?

At idle the vacuum assists removal, durring heavy load the valve becomes a brick wall.

Remove the valve, route it to a can then to preturbo. For NA, just vent. The contamination is a myth and nobody has every backed up a negative UOA with a photograph of a blown seal. However people have posted Positive UOA's with no issues while VTA.

On a NA car, durring heavy loads the crankcase vents on its own anyway wiht 0 vacuum assits. the PCV valve is closed when the flow reverses, so durring the heaviest blowby opperation, your essentially venting to atmosphere. The PCV valve is only there for providing a restrictor for a vacuum leak for a metered closed loop emissions setup.

I have spent enough money on hoses to know there is no more efficient way.


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neverlift
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not the way I would start my nico debut but to each his own.

what were you reading, look a few post up by me, that oil/water/gas s*** in that tube would ALL be in the motor, clearly as it was pulled through the hoses into the res. vta is not the "worst" but leaves unmetered air out of an important equation. A few local heros in the kat world run vta pvc with good results, I ran like that for close to a year... I no longer do.

the exhaust vent is a good idea, as the kits are designed they have a check valve that would not let air to be forced back into the CC, and they pull the crank case gas when you need it most, full throttle.

hoses alone wont cut it

Bigsyke
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neverlift wrote:not the way I would start my nico debut but to each his own.

what were you reading, look a few post up by me, that oil/water/gas s*** in that tube would ALL be in the motor, clearly as it was pulled through the hoses into the res. vta is not the "worst" but leaves unmetered air out of an important equation. A few local heros in the kat world run vta pvc with good results, I ran like that for close to a year... I no longer do.

the exhaust vent is a good idea, as the kits are designed they have a check valve that would not let air to be forced back into the CC, and they pull the crank case gas when you need it most, full throttle.

hoses alone wont cut it
Its only "pulled" once it excapes past the PCV valve. VTA has no unmetered air, if your pulling unmetered air your leaving half the system closed when both sides should be vented.

FI setup should be a no brainer, both pcv sides should run to the preturbo with no checkvalves and no restrictors.

A slash cut is hit or miss.

The oil/water/gas still remains inside the motor, there is no negative pressure evacuating these gases what so ever. The only way to put a negative pressure inside the crankcase is with an evac kit that can outflow the opposing end. OEM style is only for emission reasons to prevent the oil from dripping onto the ground, and venting vapors to the air. The OEM setup does not provide any sort of evacuation for gases. The PCV valve prevents this.

Ideally your oil will be cleaner if you vent efficiently. When the blowby is most present and the positive pressure seems to be the highest the PCV valve restricts these pressures and vapors. When the flow reverses and the positive pressure PER FSM goes through the Valve cover nipple, this is the exact same thing as venting to the air. The OE TB slash cut with the restrictor does not pull vapors, since the opposing end has a 1 way valve, thus only positive pressure is allowed inside the crankcase.

Vent without restrictions, unless your FI then run without restriction to the preturbo with cans. Or just get a decent evac kit, but the OEM setup IS worse than venting.

http://www.honda-tech.com/show...phere

I dont know why you would use a PCV valve on anything more than a stock daily driver, unless your in CA.

Modified by Bigsyke at 1:55 PM 10/19/2009
Modified by Bigsyke at 1:56 PM 10/19/2009

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Bigsyke wrote:I skimed through this article, and I like the way you regurgitated every PCV article on the web.
Dude, give me a friggin break. Everything about everything has been written about by more then one person, more then one time. All I did was share information, not once did I say I came up with this all on my own. That's called contributing, you might wanna try it without the "I'm smarter then everyone else" attitude. I read...alot. I have been reading articles and books for a long friggin time, it's an excellent way to learn. At this point, I highly doubt I'm going to come up with a truly original idea. But that doesn't stop me from reading and spreading information.

We're all here for the same thing. To improve the stock pcv system and make sure people are doing it right. Adding an oil/air separator to the stock system IS a good idea. I'm not going to re-explain it.

Running the hoses to the pipe pre-turbo is basically the same exact thing as the stock design, accept you have no vacuum at idle, or any time for that matter. I also don't like the idea of the entire intake tract being exposed to combustion leftovers vs just the intake manifold itself. The separators will never get out 100% of the crap.

I already stated that the best way to achieve crankcase evac is with a pump. But 99% of us aren't going to dump $600+ on a custom belt driven system. The next best bet is the GM or Ford pump.

What I was trying to do was explain all of the various options and break it down on several levels so that even the guys with no budget can improve their own setup. Since it's all about making the stock system better, anything that helps is a good idea, no?

The exhaust mounted evac will work great at higher rpms. You shouldn't be using a baffled muffler with a turbo, or any muffler that will be a restriction for that matter. So assuming we don't have a back pressure problem, the header/exhaust mounted system should work great when we're on boost and under high load.

I'm all about discussing options and idea's man. That's what forums are here for. We aren't trying to one up each other, we're trying to help each other as much as possible.

Thanks for pointing out that the PCV keeps pressure inside the sump, I was under the impression that vacuum opened the valve.

WD

ka-t4u
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ok so i hate to do this but i am a very visual type of person, and since there is no pictures/diagrams i have to ask, again am sorry.

so basically we are adding a vacuum pump which will have it's inlet connected to the pcv correct? with and oil/air separator in that same line, correct? and then the outlet from the pump into the intake manifold?, if so, where would the hose coming out of the valve cover go? just open to atmosphere??

again am sorry for asking a maybe stupid question,or in this case many.

and thanks for the super extra good information provided, and yes the point of the forum is to pass/share information so that more people(like me) who are very interested in learning all this stuff can find it easier.

thanks again

edit: o and by the way wd, i don't know if the number will change later, but right now your post count says 16666, i found that funny/weird


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