Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system?
07-13-2002, 01:45 PM
#1
Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? The PCV on our cars goes from the valve cover to the intake manifold but I don't think it's technically sealed, because even with the TB closed there is still a hole in it. So is there any reason why we can't route the PCV externally? I got a Summit breather tank which I plan on routing my PCV to. It will route to the tank and the air will escape via a breather on the top. The oil will drain from the filter into the tank itself and can be drained via a valve on the bottom. Seems like a good idea to me. I will re-route my PCV to stock for inspection.
I imagine the car may have the slight smell of oil in the engine bay after this, but that's all the problems I anticipate. No more oil consumption and no crankcase pressure issues (I doubt the filter is enough restriction for anything, it looks like a K&N or Metco breather).
I can't imagine our engines are any more special than any other out there. My other 2 cars have their PCV routed to the airbox (before the filter), which is a similar design, except I don't want oil collecting on my K&N (kinda redundant, I know).
Can anyone give me a reason not to do this? Is there any reason I should NOT route my PCV to the intake manifold? I see guys that just run breathers on their valve covers and so forth, but most (all) of them seem to be race-only type guys. My car is a daily driver first and a weekend dragstrip warrior second (barely, high 12s).
Dope
I imagine the car may have the slight smell of oil in the engine bay after this, but that's all the problems I anticipate. No more oil consumption and no crankcase pressure issues (I doubt the filter is enough restriction for anything, it looks like a K&N or Metco breather).
I can't imagine our engines are any more special than any other out there. My other 2 cars have their PCV routed to the airbox (before the filter), which is a similar design, except I don't want oil collecting on my K&N (kinda redundant, I know).
Can anyone give me a reason not to do this? Is there any reason I should NOT route my PCV to the intake manifold? I see guys that just run breathers on their valve covers and so forth, but most (all) of them seem to be race-only type guys. My car is a daily driver first and a weekend dragstrip warrior second (barely, high 12s).
Dope
07-13-2002, 02:25 PM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? At part throttle the PCV will pull a vacuum which will improve ring seal/life. You can run a breather and forgo this benifit - and you will also keep keep oil out of your intake.
Chris
Chris
07-14-2002, 10:42 AM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Sealed means that there's no (intentional) air
inlet to the interior (unlike older cars, where
you had the PCV valve on one side, and an air
breather on the other).
Because you're sucking in all the air/vapor/oil
that the manifold vacuum will draw, having an
air breather would screw up the mixture (since
you don't have the PCV valve to meter the flow).
There would be a source of fresh air that would
unbalance things. The crankcase vapors should be
mixture neutral, since they consist of cylinder
blow-by (already burnt for the most part).
Running without the PCV vacuum, just a breather,
means your crankcase will be running slight
positive pressure (how much depends on the amount
of blow-by, but there will always be some). That
makes the seals operate under pressure, rather
than under suction, so you should expect to see
more weeping on a car that's got some seal wear.
inlet to the interior (unlike older cars, where
you had the PCV valve on one side, and an air
breather on the other).
Because you're sucking in all the air/vapor/oil
that the manifold vacuum will draw, having an
air breather would screw up the mixture (since
you don't have the PCV valve to meter the flow).
There would be a source of fresh air that would
unbalance things. The crankcase vapors should be
mixture neutral, since they consist of cylinder
blow-by (already burnt for the most part).
Running without the PCV vacuum, just a breather,
means your crankcase will be running slight
positive pressure (how much depends on the amount
of blow-by, but there will always be some). That
makes the seals operate under pressure, rather
than under suction, so you should expect to see
more weeping on a car that's got some seal wear.
07-14-2002, 11:56 AM
#4
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? I think I explained myself poorly.
I'm still going to run a PCV valve. My PCV setup will be stock up to the valve itself. Instead of routing the hose from the PCV to the intake manifold, I'm gonna route it to one of these:
<img src="http://store.summitracing.com/global/images/prod/large/SUM-G1504.jpg" alt=" - " />
In theory, my PCV setup should act as stock, except the escaping air will be vented to atmosphere (through the breather). Thus, no oil in intake, no oil spillage either (the oil that collects in the filter will drain back into the bottle thingy and can be drained via the valve on the bottom manually). I'll cap off the hole in the intake manifold of course.
Am I making better sense? Or am I misunderstanding YOU guys?
Dope
I'm still going to run a PCV valve. My PCV setup will be stock up to the valve itself. Instead of routing the hose from the PCV to the intake manifold, I'm gonna route it to one of these:
<img src="http://store.summitracing.com/global/images/prod/large/SUM-G1504.jpg" alt=" - " />
In theory, my PCV setup should act as stock, except the escaping air will be vented to atmosphere (through the breather). Thus, no oil in intake, no oil spillage either (the oil that collects in the filter will drain back into the bottle thingy and can be drained via the valve on the bottom manually). I'll cap off the hole in the intake manifold of course.
Am I making better sense? Or am I misunderstanding YOU guys?
Dope
07-14-2002, 01:36 PM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? sounds fine to me dope. A friend of mine use to run a stefs aluminum tank like that on his car. It had hoses from each valve cover..worked fine for him.
07-15-2002, 12:32 AM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? I've always liked the looks of this unit but have never seen anyone with an LS1 f-body install one. http://www.greddy.com/products/images/oiltank.gif
07-15-2002, 06:45 AM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? sounds like a good idea. im not well versed in this pcv stuff but can you keep me updated on how it works out? id like to do something like that with my car as well. my car doesnt burn much oil YET but id like to put that system on and then run top end cleaner through it since its been sucking oil for 65k miles. some pics of where you mount it would be nice if you could be so kind <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />
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07-16-2002, 06:14 PM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Dope i was wondering if you ever put the summit breather tank on your car & if it worked. <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
07-16-2002, 06:31 PM
#9
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? I just got it in the mail today, will put it on as soon as I get some line for it. Will post my impressions and maybe a follow up. I've received some mixed opinions on the topic - the only negative responses I've gotten involve that the PCV valve may not function as well as it should if it is not routed to the intake. Something to do with the vacuum of the intake at part throttle? I don't know, I need to understand how the PCV works better. I really don't know what causes the valve to open/close, the only thing that I know for sure is that it's purpose in life is to evacuated crankcase pressure, for purposes of the seals (so they don't blow out). Theoretically it closes when the crankcase is under vacuum, so that way it can't suck in air.
*shrug*
Dope
*shrug*
Dope
07-16-2002, 06:45 PM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? I ordered a breather tank also i think im gonna try it to anything to stop oil from puddling in the damn intake.
07-16-2002, 11:30 PM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? I am interested in this topic too, but I think you have visualized the air flow backwards from what it is. The pcv valve is normally closed with a spring. The vacuum is supplied by the opening, and the tubing, that is BEHIND the throttle body blade.
The tube that is in front of the throttle blade, which leads to the top of the valve cover, is just a source of filtered air.
Think about how vacuum sources on carburators are always beneath the throttle blades.
You wrote "Theoretically it closes when the crankcase is under vacuum, so that way it can't suck in air." I am saying this is wrong because the hose that leads from behind the throttle blade indicates a vacuum source is present here. The amount of vacuum will vary, and it will be highest at de-accel, when the engine is revving high, and capable of pumping a lot of air but the butterfly is almost completely closed.
Another way to say it is that aerosol oils from the crankcase AND the pcv valve are "upstream" from the throttle body vacuum source. Your setup has no vacuum. It won't filter anything, but will function as an extra breather cap, through which blow by pressure will be released.
The pcv valve itself is designed to close under extremely high vacuum, but there seems to be a problem with this on some cars. The pcv system does not function at all without some vacuum, and I think that the spring in the pcv valve keeps itself closed until the designed-for vacuum is reached, which of course, is at some level of vacuum that GM knows but I don't.
The tube that is in front of the throttle blade, which leads to the top of the valve cover, is just a source of filtered air.
Think about how vacuum sources on carburators are always beneath the throttle blades.
You wrote "Theoretically it closes when the crankcase is under vacuum, so that way it can't suck in air." I am saying this is wrong because the hose that leads from behind the throttle blade indicates a vacuum source is present here. The amount of vacuum will vary, and it will be highest at de-accel, when the engine is revving high, and capable of pumping a lot of air but the butterfly is almost completely closed.
Another way to say it is that aerosol oils from the crankcase AND the pcv valve are "upstream" from the throttle body vacuum source. Your setup has no vacuum. It won't filter anything, but will function as an extra breather cap, through which blow by pressure will be released.
The pcv valve itself is designed to close under extremely high vacuum, but there seems to be a problem with this on some cars. The pcv system does not function at all without some vacuum, and I think that the spring in the pcv valve keeps itself closed until the designed-for vacuum is reached, which of course, is at some level of vacuum that GM knows but I don't.
07-17-2002, 10:19 PM
#12
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Well guys,
After examining all the options, I have decided on my next move. I did some research and talked to some knowledgable people (as well as the posts in here) and realized that I probably want the PCV system to act as stock as possible. Basically I wanted a completely stock PCV that just didn't deliver oil into the intake. Easier said than done, right?
I bought a Greddy Catch Can:
<img src="http://www.greddy.com/products/images/oiltank.gif" alt=" - " />
Goes between the PCV and the intake manifold. Upon entering the can itself, the crankcase gases will apparently drop any liquid (moisture/oil) and then travel back up to the outlet and to the intake manifold. This should allow stock PCV operation with no extra restrictions, while still dropping the oil out of the system. It was a bit pricey ($83) but if it does the trick, it is more than worth it. It seems every turbo import guy uses one - high crankcase pressures (ring blowby combined with extra cylinder pressure from the turbo) combined with intercoolers (oil in intercooler == bad) seem to make this an almost necessary mod. I did a search for 'greddy catch can' on google and I must've come up with 20,000 pages for installs in various turbo imports. I figure, if it's good enough for them, it's plenty for my NA motor.
Here's a link to a C5 guy's install: http://www.2phast.com/porsche/Corvette/catchcan.htm
So, in short, I will hook mine up when I get it, and see (via clear tubing) if I am still collecting oil beyond the catch can. Should be pretty easy, the oil will coat the inside of the clear hose in no time if I'm still getting oil in the intake. If so, I will probably try out my Summit breather tank.
Cons of the breather tank include oil smell, possible oil spillage (from when it goes beyond the filter - track officials may not like this either), reduced/inoperable PCV function, emissions (would have to hook up the stock PCV setup for inspection), and size (the summit tank is pretty big - about the size of the stock AC compressor!).
Pros are: low cost ($30) and NO chance of oil getting in the intake.
Cons of the Greddy Catch Can: price ($83), possibly still getting some oil in the intake.
Pros are: reduced/no oil in intake, very small (and shiny, woo!), includes all parts for the kit (bolts, hoses, etc), allows stock PCV function with no side effects, sight glass on the side.
*shrug* Will post back with some impressions when I get it. Right now, I can consume a 1/4 quart in a single night at the dragstrip (3-6 passes). Let me know what you guys think.
Dope
<small>[ July 17, 2002, 10:21 PM: Message edited by: Dope ]</small>
After examining all the options, I have decided on my next move. I did some research and talked to some knowledgable people (as well as the posts in here) and realized that I probably want the PCV system to act as stock as possible. Basically I wanted a completely stock PCV that just didn't deliver oil into the intake. Easier said than done, right?
I bought a Greddy Catch Can:
<img src="http://www.greddy.com/products/images/oiltank.gif" alt=" - " />
Goes between the PCV and the intake manifold. Upon entering the can itself, the crankcase gases will apparently drop any liquid (moisture/oil) and then travel back up to the outlet and to the intake manifold. This should allow stock PCV operation with no extra restrictions, while still dropping the oil out of the system. It was a bit pricey ($83) but if it does the trick, it is more than worth it. It seems every turbo import guy uses one - high crankcase pressures (ring blowby combined with extra cylinder pressure from the turbo) combined with intercoolers (oil in intercooler == bad) seem to make this an almost necessary mod. I did a search for 'greddy catch can' on google and I must've come up with 20,000 pages for installs in various turbo imports. I figure, if it's good enough for them, it's plenty for my NA motor.
Here's a link to a C5 guy's install: http://www.2phast.com/porsche/Corvette/catchcan.htm
So, in short, I will hook mine up when I get it, and see (via clear tubing) if I am still collecting oil beyond the catch can. Should be pretty easy, the oil will coat the inside of the clear hose in no time if I'm still getting oil in the intake. If so, I will probably try out my Summit breather tank.
Cons of the breather tank include oil smell, possible oil spillage (from when it goes beyond the filter - track officials may not like this either), reduced/inoperable PCV function, emissions (would have to hook up the stock PCV setup for inspection), and size (the summit tank is pretty big - about the size of the stock AC compressor!).
Pros are: low cost ($30) and NO chance of oil getting in the intake.
Cons of the Greddy Catch Can: price ($83), possibly still getting some oil in the intake.
Pros are: reduced/no oil in intake, very small (and shiny, woo!), includes all parts for the kit (bolts, hoses, etc), allows stock PCV function with no side effects, sight glass on the side.
*shrug* Will post back with some impressions when I get it. Right now, I can consume a 1/4 quart in a single night at the dragstrip (3-6 passes). Let me know what you guys think.
Dope
<small>[ July 17, 2002, 10:21 PM: Message edited by: Dope ]</small>
07-26-2002, 05:23 PM
#13
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Update:
I got my Greddy Catch Can installed. It fit perfectly where I chose it:
<img src="http://www.fear.net/~dope/camaro/intake/catch_can/catchcan_installed.jpg" alt=" - " />
I chose this location because:
1) Doesn't hit the hood
2) Doesn't get in the way of anything but the battery (it only attaches with one bolt anyway so it's not a big deal)
3) Supplied clear tubing fit
4) Good path to PCV and intake fitting
5) Easy to remove for drainage
6) Easy to view sight glass
You can mount it up front, right behind or right next to the passenger headlight, but you'll need more tubing.
I haven't done any WOT action, only did my work commute (about 22 miles) and you can already see the difference. Look at the inlet and outlet hoses (bottom one is the inlet, from the PCV, top is into the intake manifold)
<img src="http://www.fear.net/~dope/camaro/intake/catch_can/inlet+outlet-comparison.jpg" alt=" - " />
Case closed for now. Will see how much (if any) oil is getting beyond the catchcan. Even if it doesn't get all of it, it will be getting 95% or more. Might just be good enough for me.
An interesting side effect, my oil pressure at idle has gone up 5-6psi. I used to run the SMH PCV setup (90* pcv with 2 fuel filters and a crappy catch can inline with the PCV tubing). It must have been restrictive or something because I used to see 32psi oil pressure at idle, in drive (550rpm) with the engine fully hot. Now I'm seeing 37-38 (almost straight up). Interesting indeed.
Rest of the pics (closeups and so forth) are at: http://www.fear.net/~dope/camaro/intake/catch_can/
Dope
I got my Greddy Catch Can installed. It fit perfectly where I chose it:
<img src="http://www.fear.net/~dope/camaro/intake/catch_can/catchcan_installed.jpg" alt=" - " />
I chose this location because:
1) Doesn't hit the hood
2) Doesn't get in the way of anything but the battery (it only attaches with one bolt anyway so it's not a big deal)
3) Supplied clear tubing fit
4) Good path to PCV and intake fitting
5) Easy to remove for drainage
6) Easy to view sight glass
You can mount it up front, right behind or right next to the passenger headlight, but you'll need more tubing.
I haven't done any WOT action, only did my work commute (about 22 miles) and you can already see the difference. Look at the inlet and outlet hoses (bottom one is the inlet, from the PCV, top is into the intake manifold)
<img src="http://www.fear.net/~dope/camaro/intake/catch_can/inlet+outlet-comparison.jpg" alt=" - " />
Case closed for now. Will see how much (if any) oil is getting beyond the catchcan. Even if it doesn't get all of it, it will be getting 95% or more. Might just be good enough for me.
An interesting side effect, my oil pressure at idle has gone up 5-6psi. I used to run the SMH PCV setup (90* pcv with 2 fuel filters and a crappy catch can inline with the PCV tubing). It must have been restrictive or something because I used to see 32psi oil pressure at idle, in drive (550rpm) with the engine fully hot. Now I'm seeing 37-38 (almost straight up). Interesting indeed.
Rest of the pics (closeups and so forth) are at: http://www.fear.net/~dope/camaro/intake/catch_can/
Dope
07-26-2002, 07:26 PM
#14
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DARK AGE 53:
<strong>I've always liked the looks of this unit but have never seen anyone with an LS1 f-body install one. http://www.greddy.com/products/images/oiltank.gif</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">TA/Dragster, TA/FC's, TF/Dragster and TF/FC's run a system similar to what you describe. The call the catch pan a "Puke Tank". It is emptied after every run.
<strong>I've always liked the looks of this unit but have never seen anyone with an LS1 f-body install one. http://www.greddy.com/products/images/oiltank.gif</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">TA/Dragster, TA/FC's, TF/Dragster and TF/FC's run a system similar to what you describe. The call the catch pan a "Puke Tank". It is emptied after every run.
07-26-2002, 07:51 PM
#15
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by DARK AGE 53:
<strong>I've always liked the looks of this unit but have never seen anyone with an LS1 f-body install one. http://www.greddy.com/products/images/oiltank.gif</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, now you have <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
This is funny, I just now saw your post. Must have skimmed over it the first time.
Dope
<strong>I've always liked the looks of this unit but have never seen anyone with an LS1 f-body install one. http://www.greddy.com/products/images/oiltank.gif</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Well, now you have <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />
This is funny, I just now saw your post. Must have skimmed over it the first time.
Dope
07-26-2002, 09:19 PM
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Looks good Dope, did you make the bracket or does it come with one? If you paid $83 for it I wouldn't call it a "con", that's the best price I ever heard of, who did you get it from? I just installed a Cusco tank on my Prowler but if I can get the GReddy tank I'll change it out, I'll also be changing the clear hose for yellow silicone hose in the future. Here's what mine looks like now.
<img src="http://groups.msn.com/_Secure/0MwAAACgR3p4GFPZqjjeAWEB29I6NALwuduRV0r04xbfI*dnVs FRnPEmdh2FkQb4JoAWuvHiZnKaRf1ZiE7lIWQ/C13.JPG" alt=" - " />
<img src="http://groups.msn.com/_Secure/0MwAAACgR3p4GFPZqjjeAWEB29I6NALwuduRV0r04xbfI*dnVs FRnPEmdh2FkQb4JoAWuvHiZnKaRf1ZiE7lIWQ/C13.JPG" alt=" - " />
07-26-2002, 09:58 PM
#17
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Hey Dark Age,
Thanks. I got mine from Options Auto or something -> http://www.optauto.com/webstore/prod...k=yes&dept=876
The bracket is like $5 from Greddy as well. It's just a universal t-bracket that I cut and bent.
I got the can about 7-8 days after I placed the order.
I saw the Cusco tanks too, they were like $20 more though and didn't seem to do anything special, so I figured - why not save a few bucks? They look nice though...shiny!
Dope
Thanks. I got mine from Options Auto or something -> http://www.optauto.com/webstore/prod...k=yes&dept=876
The bracket is like $5 from Greddy as well. It's just a universal t-bracket that I cut and bent.
I got the can about 7-8 days after I placed the order.
I saw the Cusco tanks too, they were like $20 more though and didn't seem to do anything special, so I figured - why not save a few bucks? They look nice though...shiny!
Dope
07-30-2002, 12:41 AM
#19
Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? It's working great so far.
I'll take some more comparison pics in a week or two, but right now the inlet hose has tons of oil and water in it, and the outlet looks as clear as it did when it started.
I am impressed.
Dope
I'll take some more comparison pics in a week or two, but right now the inlet hose has tons of oil and water in it, and the outlet looks as clear as it did when it started.
I am impressed.
Dope
07-30-2002, 02:52 AM
#20
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Re: Is there any actual reason (besides emissions) for the PCV to be a 'sealed' system? Hey Dope
Do you have any instructions on how to install the catch can???
Do you have any instructions on how to install the catch can???