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PCV Venting to Catch Can

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Old Jun 6, 2006 | 10:49 AM
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Default PCV Venting to Catch Can

Here's my idea.

hose from factory spot on rear drivers side head to catch can

hose from smaller spot on driver side head to same catch can

hose from LS6 valley cover pcv to same catch can

leave fresh air from TB to pass head connected.

Will this vent enough? I won't be hooking up the manifold vacumme to it. I dont want to run breathers and have oil everywhere at the track (road racing) like last time. Will this be enough to vent the pressure or will the lines not flow like a breather would?
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Old Jun 6, 2006 | 11:01 AM
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Originally Posted by nytoy
Here's my idea.

hose from factory spot on rear drivers side head to catch can

hose from smaller spot on driver side head to same catch can

hose from LS6 valley cover pcv to same catch can

leave fresh air from TB to pass head connected.

Will this vent enough? I won't be hooking up the manifold vacumme to it. I dont want to run breathers and have oil everywhere at the track (road racing) like last time. Will this be enough to vent the pressure or will the lines not flow like a breather would?
With all those lines running into a common catchcan, I think it would flow enough. You could put that catchcan somewhere low, then run a discharge line from it and attatch a small filter up higher. If you're doing this, I would get rid of the fresh air tube or put a check valve inline so you don't blow anything into the TB. It's not really going to be able to suck in air through the fresh air tube if there is no vacuum on the crankcase.
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Old Jun 6, 2006 | 01:14 PM
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It's the AMW catch can with there mount, which is a little bit lower than most of these lines. Good idea with the fresh air tube. Anyone else think this will let it breathe enough? I don't want to blow out another front cover gasket...
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Old Jun 7, 2006 | 08:57 AM
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Old Jun 7, 2006 | 02:49 PM
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That will work fine. It will releive crank pressure.
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Old Jun 8, 2006 | 09:03 AM
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Originally Posted by Bomber Z
That will work fine. It will releive crank pressure.
Cool, thanks for the input.
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Old Jun 8, 2006 | 11:39 AM
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Like everyone said, that setup will vent just fine. However, if you'd like a little suction to aid in pressure evacuation you could go with a closed loop setup like mine https://ls1tech.com/forums/generation-iii-internal-engine/512297-found-while-changing-pcv-valve.html After one tank of gas (about 260 miles) the "catchcan" I'm using was about 1/3 full. The hose that goes between the catchcan and the TB is bone dry as well. So it seems like the catchcan has been doing a good job of collecting the oil vapors. It's a good alternative setup if emissions legality is an issue where you live. I'm doing it only as a trial setup right now until I get my next oil analysis done.

If you're going for the cleanest intake tract possible then your proposed setup would do just fine. However, your oil will get dirty quicker...but if you're a 3k mile oil change person then it's a non-issue. Also, your setup will vent the excess pressure but you won't have the advantage of vacuum in the crankcase for ring sealing. Again, probably a non-issue unless you're running an all out race motor. I had a setup similar open atmosphere setup on one of my other cars for over 70k miles and there were no adverse effects from it.
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Old Jun 12, 2006 | 09:26 AM
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I tried it and need some one-way vacumm valves that only allow the engine to breath out and not suck back in, does anyone know where to get these?
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Old Jun 12, 2006 | 01:45 PM
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Originally Posted by nytoy
I tried it and need some one-way vacumm valves that only allow the engine to breath out and not suck back in, does anyone know where to get these?
Which setup did you try? A PCV valve will accomplish what you're talking about if you go with my setup. If you're running open atmosphere (like your proposed setup) and you wanna use check valves, you can try. By design, the check valves will be more prone to gumming up, though. But to answer your question, you can find check valves in the Help! section of your local auto parts store.
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Old Jun 12, 2006 | 01:51 PM
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I tried the setup where I ran all three pcv lines to a closed catch can, and that's it. The problem was the engine sucked back in the fumes in the catch can once under decelleration.

I tried the local auto parts store and the Help! sections, nothing I'm looking for, I've found that the standard PCV valves don't seal up under vaccum, so I ordered a custom valve com mcmaster.com, we'll see how it works. I guess I should vent my catch can to open air, but I'll try it closed first.
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Old Jun 12, 2006 | 02:15 PM
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Whoa...if you're venting everything to a closed catchcan that could spell trouble. You'd actually be creating more pressure in your crankcase with this setup. I don't know if that one hose left connected between the valve cover and TB would provide enough "pressure relief". I guess I didn't read your original post close enough to realize that this would be a potentially bad idea. If you decide to incorporate that custom check valve into your closed catchcan setup all you'll be doing is building up pressure inside your closed catchcan...where's it going to go? Then, when the pressure inside the cathcan is greater than the pressure inside your crankcase, the check valve will be rendered non-functional. After the check valve is rendered non-functional, where will the built up crankcase pressure go? Will the one hose still connected between the valve cover and the TB be enough to vent the excess pressure? I don't know...the pressure in your crankcase might be too much for that one little hose. The excess pressure could then place undue strain on your rings.
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