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Some final ?'s on !PCV, vented valve covers, and puke tank

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Old 12-16-2010, 01:24 AM
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Default Some final ?'s on !PCV, vented valve covers, and puke tank

I'm posting this in this section because this is where I gained most of my information on PCV removal for a FI setup.

I'm putting out 500+ RWHP on a stock 346 Maggie MP112 setup and still running the stock PCV and have some simple questions for you guys running a breather can vented from both valve covers with -10 fittings. The excess pressure and venting back into my supercharger concerns me a bit.

I gathered the majority of FI builds are running this setup and it is generally regarded as the simplest and best, correct? No catch can, no breather, no PCV system at all, just a puke tank.

I'm looking at the allstar breather tank and nasty performance valve covers to keep this simple and looking sharp. Are you guys using dual inlets on the breather can or a t fitting to a single? I'm considering duals.

What are the oil change intervals like with this configuration? I'm religous about using Royal Purple and their filters. My car is not a track only car, sees a fair amount of street use and also spends quite a bit in storage.

Just looking for some more input before I pull the trigger on these parts.

Thanks,
Old 12-16-2010, 09:46 AM
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When I had my procharger set-up with a basically stock 346 i made 630rwhp and only didnt have the pcv junk and just ran a line off the valve cover to a oil/water sep. and then had an air filter on the end venting to the atmosphere. Then when I changed everything over to the turbo set-up we did a catch can with two ports, one off the valve cover, and the other coming from the valley plate. Then put a filter on the driver side valve cover and that worked pretty good.
Old 12-16-2010, 10:17 AM
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I can't use a valley cover that integrates into the PCV. My valley cover is low profile to accomodate the top mount blower so I'm stuck with the LS1 PCV.
Old 12-16-2010, 10:23 AM
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Basically I'm going to do this.




What do you guys think about this setup?
Old 12-16-2010, 11:25 AM
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Whether you do 2 lines or "T" it to one line makes no difference. We build catch cans with breathers and its the preferred method with our covers and especially boost.
Old 12-16-2010, 11:43 AM
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It might be the simplest but it's not the best. Plenty of people run a P.C.V. system on here. I run one because I don't want the nasty smell and quicker contamination of the oil due to the blowby gases not getting removed from the crankcase. A P.C.V. system is not that difficult, catch can, a check valve and some plumbing.
Old 12-16-2010, 12:50 PM
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Originally Posted by 2001WS6Vert
It might be the simplest but it's not the best. Plenty of people run a P.C.V. system on here. I run one because I don't want the nasty smell and quicker contamination of the oil due to the blowby gases not getting removed from the crankcase. A P.C.V. system is not that difficult, catch can, a check valve and some plumbing.
doesnt that put the oil back into the intake and into the heads. I dont see how that can be good for combustion under boost.
Old 12-16-2010, 04:32 PM
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It will work fine, just remember to check your can every so often.
Old 12-16-2010, 04:33 PM
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Originally Posted by 71 chevy
doesnt that put the oil back into the intake and into the heads. I dont see how that can be good for combustion under boost.
Not if you have a sealed catch can and check valve in between.

My setup is this:

Valley cover to sealed catch can to one way valve to intake. This provides scavenging under part throttle and the valve closed under boost to avoid pressurizing the crankcase.

Both valve covers to vented catch can. This provides a fresh air inlet for the PCV system under part throttle and also venting under boost without mess.

A vent system is the easiest but not the best IMO. Ill take the benifits of a PCV system when its not that hard to do it right.

Yours is a little harder but it can still be done. If you dont want the hassle, yes throw on the breather lines and catch can.
Old 12-16-2010, 08:53 PM
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There are several ways, all of which have disadvantages from what I gather. I understand about the reduced oil life, but by how much. JLWS6 has done numerous oil tests and sais that the decreased oil life with or without PVC is negligible and nothing to be concerned about.

Like I said, I run quality oil and filters, as long as I get 3k miles out of an oil change that's fine.

One thing I still don't understand is how these gases are believed to accumulate and accelerate oil degradation when both valve covers would be vented? Vented as in open to the environment yet filtered. There shouldn't be a problem with them escaping. Not to mention boost creating more crankcrase pressure assisting in the venting process.

N8, I sent you a message through your site about your covers.
Old 12-17-2010, 04:12 AM
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I've been trying to learn alot about PCV and I was recently browsing the GTO forums. Reason being alot of guys are running Maggies over there so it is informative. There was a thread over there posted by a seemingly well knowledged user. I'm sure this will spark alot of debate but I'll post it anyway.
He stated that he used to be all for keeping the PCV and its benefits until he was politely corrected by Jeremy Formato. If you didn't know he is a very well respected LSX tuner that may still sponsor this site. He has tuned more LS engines than probably 90 percent of us have seen. Now this is 3rd hand information so I'll post what I take his thoughts as being through that poster.

Basically, the benefits of keeping the PCV system do not outweigh the benefits of removing it. LS engine users are making big power by way of SC's, TC's, and N20. The stock PCV can barely properly ventilate a stock engine. Regardless if you run a catchcan or not, oil vapors are going to enter your intake charge. This can result in carbon buildup on your pistons which can alter your PTV clearances, compression ratio, and create piston hotspots leading to detonation, pulling timing, knock, and a generally inconsistent charge. As for the additional oil contaminants, these contaminates are boiled off as soon as the oil reaches operating temperature.

I looked for the thread briefly but couldn't find it. What do you guys think?
Old 12-17-2010, 06:20 AM
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Since you use Royal Purple I would think you care about clean oil. As a prof. mechanic I have seen the yellow sludge many times in various engines and most of the times it can be traced to P.C.V. problems. Obviously It's not possible for carbon to get between the piston and valve. The smell you will get alone would cause me to use a P.C.V. system (nasty sh#t). It is hard enough on the oil with boost let alone throw in a deleted P.C.V. system. As far as carbon buildup I'd like to see comparative pictures of an engine disassembled that was ran X amount of miles with and without a P.C.V. system to prove the case. To each his own though.
Old 12-17-2010, 06:32 AM
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Every PCV system has a fresh air inlet. On a stock system its usually a nipple on the air intake system. On mine, it would be the two valve covers to the vented catch can. Fresh air under vacuum and venting under boost. It cant be totally sealed otherwise it will whistle and suck in the seals.




Originally Posted by joblo1978
There are several ways, all of which have disadvantages from what I gather. I understand about the reduced oil life, but by how much. JLWS6 has done numerous oil tests and sais that the decreased oil life with or without PVC is negligible and nothing to be concerned about.

Like I said, I run quality oil and filters, as long as I get 3k miles out of an oil change that's fine.

One thing I still don't understand is how these gases are believed to accumulate and accelerate oil degradation when both valve covers would be vented? Vented as in open to the environment yet filtered. There shouldn't be a problem with them escaping. Not to mention boost creating more crankcrase pressure assisting in the venting process.

N8, I sent you a message through your site about your covers.
Old 12-17-2010, 07:28 AM
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Originally Posted by 2001WS6Vert
Since you use Royal Purple I would think you care about clean oil. As a prof. mechanic I have seen the yellow sludge many times in various engines and most of the times it can be traced to P.C.V. problems. Obviously It's not possible for carbon to get between the piston and valve. The smell you will get alone would cause me to use a P.C.V. system (nasty sh#t). It is hard enough on the oil with boost let alone throw in a deleted P.C.V. system. As far as carbon buildup I'd like to see comparative pictures of an engine disassembled that was ran X amount of miles with and without a P.C.V. system to prove the case. To each his own though.
I'm sure as a professional mechanic you see lots of things. People that run conventional oil for 10k without changing it, and then you trying to unclog oil pans with a pencil after the drainage bolt has been removed. Clogged PCV's as a result of this and then the engine not being able to vent because it DOESN''T have a breather. How can I have a PCV problem if I dont' have a PCV? PCV is strictly emissions related.

I use RP because I care about the best lubrication I can get. I change it every 3k because I care about clean oil. Any brand oil is "clean" when it's new. There are plenty of pics around here of guys that have kept PCV's intact with and without a catchcan. Many pics of guys running breathers and no PCV on big dollar setups too.

So what are you saying here?
Old 12-17-2010, 10:54 AM
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P.C.V. issues can happen even if the oil is changed every 3k. The valve should periodically be changed. If the valve gets clogged it still is vented through the inlet side, there is always an air inlet for the P.C.V. system. It may be an emission control but it is ALSO key in prolonging oil life. I won't bother your thread anymore.
Old 12-17-2010, 12:37 PM
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I've got a maggie too. The stock PCV gets fresh air from the TB before the blade. This fresh air goes into the passenger side valve cover. The dirty air comes out of the back of the drivers side valve cover. So the air is going in one head, across the valley and crankcase and back out of the other valve cover so the air is not stagnant, it is constantly being replaced with fresh air. The moisture and combustion vapors are carried away in this air stream. You can use a catch can to collect the liquids and solids, any aromatic fumes are un-burned hydrocarbons and won't affect the octane going into the motor, it's the same gas as being injected and this is a pretty slight amount.

Will it make a big difference? If you drive the car infrequently and it doesn't get up into operating temperature every time. If not, you're introducing water vapor in the crankcase which eventually becomes sludge producing. If you're just running an open system, you stand a better chance of getting moisture than you would if you tied both valve covers without a PCV system and into a collection can since the path for the humid air entering the crankcase is longer and there isn't really any flow, just an opening for the air path. Bottom line is some kind of fresh air is best. The very best is a vacuum pump with a metered air inlet to maintain vacuum in the crankcase to reduce parasitic pumping loss (due to combustion gas seapage past the rings).

As I said, I've had a Maggie on my old GTO and now on my Volvo an they've both had catch cans installed. I made the one on the Volvo though, I wanted zero oil going into the motor and it seems to work pretty well.

I have an electric vacuum pump on my Geo, it literally sounds like my car has an Electrolux vacuum cleaner under the hood when it's running. Not sexy at all but very powerful unit. Came from a BMW and is about twice the pump the LS1 used.

Last edited by Nashty; 12-17-2010 at 12:40 PM. Reason: vacuum pump
Old 12-18-2010, 04:16 AM
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So explain this to me...

If you have positive crankcase pressure, positive intake pressure, (BOOST! Which my car makes at 3/8 throttle) and the PCV in the middle, how does the crankcase ventilate at all? The PCV valve shouldn't open with high pressure on either side of it and would therefore render it worthless. It's not doing anything but keeping the system closed, trapping this gas (where it may contaminate oil) and putting undue stress and heat on engine seals.

How is a simple catchcan going to trap vapors anyway? I'm no genius, but I know the simple process of vapor traveling from a small closed system, to a larger closed system will not result in 100% instant condensation without some sort of serious cooling going on. You could run 2, 3, or even 4 catch cans and your still not going to "catch" these byproducts of boiling oil that are being routed back into the intake, fouling up the intake charge, and coating my intercooler and expensive supercharger with oil and raising IATs more than likely.

You're also trying to tell me that the factory 3/8" line (which is under ambient pressure no less) which runs to the front of the driver side valve cover from the TB is also providing sufficient fresh air to ventilate and evacuate my entire crankcase which is under high pressure? I don't think so, especially not under boost.

Why not just let the crap vent naturally out of the valvecovers under normal driving AND boost considering all emissions aside? It's HOT! It will naturally want to depart the engine in this manner. Running dual breathers on either valve cover would only shorten and simplify this process. I mean ****, these gases are probably so trapped by the stock PCV that they probably try and vent themselves through the tubing that was supposedly to let fresh air in.

The entire system was developed simply to please those idiots at the EPA and eliminate the road draft tube. My headers, supercharger, smog pump, and other emissions that found its way into the trash aren't pleasing them, so why should my PCV?

The more and more I read and study this PCV setup I'm learning it's not related to oil life at all. Simply emissions.

Hell, I've read on here somewhere that back to back dyno runs on highly modified import engines with and without the PCV setup have resulted in a 14 WHP gain without the PCV.

Somebody please correct me if I'm wrong...

Last edited by joblo1978; 12-18-2010 at 04:42 AM.
Old 12-18-2010, 05:56 AM
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Originally Posted by joblo1978
Basically I'm going to do this.




What do you guys think about this setup?
Im going to do this same setup, but have a -10 bung welded to the middle of the catch can. Then from that bung run it to another fitting on my downpipe so it pulls the vapors from the whole system and purges it at will.

Totally SMOG compliant might i add....
Old 12-18-2010, 06:25 AM
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No matter what you read here, your just going to run the vented valved covers so just do it already.
Old 12-18-2010, 06:48 AM
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Originally Posted by LS1NOVA
No matter what you read here, your just going to run the vented valved covers so just do it already.
No, please, enlighten me.


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