Metco breather
07-05-2005 | 07:42 AM
#22
Your wrong Im telling you man, they ran the same exact setups on carbed cars years ago its the same principle. Carbed cars worked the same way, any air they pulled through the fresh air breather that was circulated through the engine out the pcv had to be accounted for once it reached the carb. Then they would tinker and turn screws to get the A/F correct, because they were metering or tuning for that increase of air. http://home.tiscali.be/be058723/dodge/emis3.jpg
This statement of yours proves my point. You just stated that the engine has to be "tuned" for the PCV air. Correct! End of story. Why? Because it is basicly a VACUUM leak that is CONTROLLED or METERED by the PCV valve thus making it "tunable". The point where you draw fresh air is irrelevent, except for emissions purposes where excess blowby can be sucked directly back into the carb or TB. Feel free to read the GM factory service manual for your LS1 car, which plainly states that PCV air is "metered" by the PCV valve. The tiny fraction of fresh air that is siphoned off from behind the MAF and before the TB for the PCV system is practically inconsequential to the combustion efficiency of MAF metering.
I'm not really interested in what Speed Inc or anyone else "says". I gave a you several tests to conduct to prove what I'm saying. Anything else is mere speculation and theory.
You can hook up a scan tool and then completely plug off all your PCV system and watch the LTFT's change. Once again WHY? Because the PCM has been "tuned" for this system. Remove it and it becomes untuned, albeit slightly, but still...
Your lost man go back to auto class read the books twice then try to apply it to the real world. Book smarts dont mean crap unless you have experience. Im done with you and wont read another post off this thread. But feel free to post again so you can make yourself look even smarter.
Now this is just childish and really deserves no response. Everything I know in my 25+ years of automotive experience, which may not be much, was learned in the "real world" through much trial, error and study. I never said I was smarter than anyone. You sir jumped into this thread and stated that I had no idea what I was talking about and basicly insulted me.
This statement of yours proves my point. You just stated that the engine has to be "tuned" for the PCV air. Correct! End of story. Why? Because it is basicly a VACUUM leak that is CONTROLLED or METERED by the PCV valve thus making it "tunable". The point where you draw fresh air is irrelevent, except for emissions purposes where excess blowby can be sucked directly back into the carb or TB. Feel free to read the GM factory service manual for your LS1 car, which plainly states that PCV air is "metered" by the PCV valve. The tiny fraction of fresh air that is siphoned off from behind the MAF and before the TB for the PCV system is practically inconsequential to the combustion efficiency of MAF metering.
I'm not really interested in what Speed Inc or anyone else "says". I gave a you several tests to conduct to prove what I'm saying. Anything else is mere speculation and theory.
You can hook up a scan tool and then completely plug off all your PCV system and watch the LTFT's change. Once again WHY? Because the PCM has been "tuned" for this system. Remove it and it becomes untuned, albeit slightly, but still...
Your lost man go back to auto class read the books twice then try to apply it to the real world. Book smarts dont mean crap unless you have experience. Im done with you and wont read another post off this thread. But feel free to post again so you can make yourself look even smarter.
Now this is just childish and really deserves no response. Everything I know in my 25+ years of automotive experience, which may not be much, was learned in the "real world" through much trial, error and study. I never said I was smarter than anyone. You sir jumped into this thread and stated that I had no idea what I was talking about and basicly insulted me.
07-05-2005 | 07:59 AM
#23
The stock PCV system is not a "("tuned")vaccum leak." Think about it. Where does the PCV system get the fresh air from? It is a sealed system and the fresh air must come from the outside correct? ALL outside air goes through the MAF. The air going from the TB to the valve cover means nothing, because the air that comes from the hole in the throttle body must first go through the MAF and is most certainly accounted for.
Try something tomorrow. With your engine running. Pull of the fresh air hose from your TB and then plug the TB hole. Anything change? This hose does not siphon off enough MAF metered air to amount to anything. This is simply a good logical place to draw clean filtered air into the engine for proper crankcase ventilation.
You will have a vacuum leak if you use a breather and still keep the PCV system,
Well I run a breather and an LS6 PCV system. The factory fresh air ports on the TB and valve cover are plugged. I have no vacuum leak in the uncontrolled form in which you are referring. How is this explained?
but if you do away with the entire PCV system and just use a breather you should be fine, except for the risk of gunk inside your engine.
Well, except, I really don't want gunk in my engine
Try something tomorrow. With your engine running. Pull of the fresh air hose from your TB and then plug the TB hole. Anything change? This hose does not siphon off enough MAF metered air to amount to anything. This is simply a good logical place to draw clean filtered air into the engine for proper crankcase ventilation.
You will have a vacuum leak if you use a breather and still keep the PCV system,
Well I run a breather and an LS6 PCV system. The factory fresh air ports on the TB and valve cover are plugged. I have no vacuum leak in the uncontrolled form in which you are referring. How is this explained?
but if you do away with the entire PCV system and just use a breather you should be fine, except for the risk of gunk inside your engine.
Well, except, I really don't want gunk in my engine
07-05-2005 | 11:00 AM
#24
TECH Regular
Joined: Mar 2002
Posts: 433
Likes: 0
My PCV setup is very similar. I went from catch can + LS6 PCV through breathers only to breathers + restricted LS6 PCV + catch can. PCV now pulls through ~1/16 inch restriction+PCV valve... I added it to make it more certain oil is not pulled through when closing throttle at high RPM, anyway, no gunk or crankcase pressure build up.
The unmetered amount of air is likely don't care and is compensated by LTFTs. If you don't want them positive then tune the VE accordingly but I doubt the LTFTs are much affected if at all though...the effect would be very easy to verify as Dustin suggests... If there was any effect in my case it's now buried under VE table changes anyway. VE table close to idle is significantly lower than stock which means the fueling change due to air not going through MAF is insignificant compared to VE change due to cam and other mods.
Close to idle fueling control is dominated by calculations based on VE table and MAF portion is small, at higher RPM MAF is taken more and more into account but at the same time air through PCV becomes even less significant compared to overall flow ... also because pressure difference between manifold and crankcase is lower.
The unmetered amount of air is likely don't care and is compensated by LTFTs. If you don't want them positive then tune the VE accordingly but I doubt the LTFTs are much affected if at all though...the effect would be very easy to verify as Dustin suggests... If there was any effect in my case it's now buried under VE table changes anyway. VE table close to idle is significantly lower than stock which means the fueling change due to air not going through MAF is insignificant compared to VE change due to cam and other mods.
Close to idle fueling control is dominated by calculations based on VE table and MAF portion is small, at higher RPM MAF is taken more and more into account but at the same time air through PCV becomes even less significant compared to overall flow ... also because pressure difference between manifold and crankcase is lower.
Last edited by pekkaz; 07-05-2005 at 12:00 PM.
07-05-2005 | 12:12 PM
#25
[QUOTE=Dustin Butts]Try something tomorrow. With your engine running. Pull of the fresh air hose from your TB and then plug the TB hole. Anything change? This hose does not siphon off enough MAF metered air to amount to anything. This is simply a good logical place to draw clean filtered air into the engine for proper crankcase ventilation.
Exactly!! You said it yourself, then why mess with the location where the air is pulled from in the first place?
Well I run a breather and an LS6 PCV system. The factory fresh air ports on the TB and valve cover are plugged. I have no vacuum leak in the uncontrolled form in which you are referring. How is this explained?
You do have a vacuum leak weather you know it or not.
Well, except, I really don't want gunk in my engine
Then don't mess with the stock PCV system in the first place.
[QUOTE]
Exactly!! You said it yourself, then why mess with the location where the air is pulled from in the first place?
Well I run a breather and an LS6 PCV system. The factory fresh air ports on the TB and valve cover are plugged. I have no vacuum leak in the uncontrolled form in which you are referring. How is this explained?
You do have a vacuum leak weather you know it or not.
Well, except, I really don't want gunk in my engine
Then don't mess with the stock PCV system in the first place.
[QUOTE]
07-05-2005 | 12:47 PM
#26
TECH Enthusiast
Joined: Nov 2001
Posts: 696
Likes: 0
From: Rockland County, NY
Dustin
I have a Metco breather and I plugged the fresh air at the driver side valve cover and the TB. However, I left the PCV draw at the driver side intact, along with the passenger side. In other words, the PCV system is pretty much the way it was stock (except for adding a catch can). Why do I need to cap off the PCV on the drivers side since both sides are tee'd together?
I have a Metco breather and I plugged the fresh air at the driver side valve cover and the TB. However, I left the PCV draw at the driver side intact, along with the passenger side. In other words, the PCV system is pretty much the way it was stock (except for adding a catch can). Why do I need to cap off the PCV on the drivers side since both sides are tee'd together?
07-05-2005 | 12:51 PM
#27
Originally Posted by Phil99TA
Dustin
I have a Metco breather and I plugged the fresh air at the driver side valve cover and the TB. However, I left the PCV draw at the driver side intact, along with the passenger side. In other words, the PCV system is pretty much the way it was stock (except for adding a catch can). Why do I need to cap off the PCV on the drivers side since both sides are tee'd together?
I have a Metco breather and I plugged the fresh air at the driver side valve cover and the TB. However, I left the PCV draw at the driver side intact, along with the passenger side. In other words, the PCV system is pretty much the way it was stock (except for adding a catch can). Why do I need to cap off the PCV on the drivers side since both sides are tee'd together?
07-05-2005 | 04:50 PM
#28
Originally Posted by Phil99TA
Dustin
I have a Metco breather and I plugged the fresh air at the driver side valve cover and the TB. However, I left the PCV draw at the driver side intact, along with the passenger side. In other words, the PCV system is pretty much the way it was stock (except for adding a catch can). Why do I need to cap off the PCV on the drivers side since both sides are tee'd together?
I have a Metco breather and I plugged the fresh air at the driver side valve cover and the TB. However, I left the PCV draw at the driver side intact, along with the passenger side. In other words, the PCV system is pretty much the way it was stock (except for adding a catch can). Why do I need to cap off the PCV on the drivers side since both sides are tee'd together?
07-05-2005 | 05:03 PM
#29
TECH Enthusiast
Joined: Nov 2001
Posts: 696
Likes: 0
From: Rockland County, NY
Originally Posted by Dustin Butts
Good question Phil. The reason is because when the PCV vaccum is pulling on the passengers side(the side with the breather) it's really only pulling air on that side across the top of the head. It's pulling air straight from the breather across the top of the pass side head into the pcv vacuum hose. IMO not the best case scenario. If you block the pass(breather) side pcv vacuum hose, you'll be pulling air in through the breather, thru the engine crankcase and up into the drivers side pcv vacuum and back into the combustion process.
But it sounds like you understand what I meant 
07-05-2005 | 05:06 PM
#30
Exactly!! You said it yourself, then why mess with the location where the air is pulled from in the first place?
My engine is in no shape or form stock. I have larger bore, stroke, cam, heads, but perhaps most important ti this particular discussion: larger ring gaps. This means more crankcase pressure and blowby(by design). I've already stated I wanted more area to vent crankcase pressure. Running the breather and PCV the way I have stated cures this problem and does not affect engine performance negatively at idle, WOT or anywhere in between. The stock PCV system is not adequate for my application. It is barely adequate for stock. The PCV fresh air intake hose on my V6 truck is at least 2 times larger than the stock fresh air hose on my Camaro was.
You do have a vacuum leak weather you know it or not.
I believe I've already stated that I DO indeed have a vaccum leak only it's not an uncontrolled, erratic, untuned, performance disturbing leak. I think I've also tried to explain more than once that a PCV system is basicly a controlled, tuned, vacuum leak.
Then don't mess with the stock PCV system in the first place.
Well then let's just shut down this site and all leave our cars bone stock and be done with it.
My engine is in no shape or form stock. I have larger bore, stroke, cam, heads, but perhaps most important ti this particular discussion: larger ring gaps. This means more crankcase pressure and blowby(by design). I've already stated I wanted more area to vent crankcase pressure. Running the breather and PCV the way I have stated cures this problem and does not affect engine performance negatively at idle, WOT or anywhere in between. The stock PCV system is not adequate for my application. It is barely adequate for stock. The PCV fresh air intake hose on my V6 truck is at least 2 times larger than the stock fresh air hose on my Camaro was.
You do have a vacuum leak weather you know it or not.
I believe I've already stated that I DO indeed have a vaccum leak only it's not an uncontrolled, erratic, untuned, performance disturbing leak. I think I've also tried to explain more than once that a PCV system is basicly a controlled, tuned, vacuum leak.
Then don't mess with the stock PCV system in the first place.
Well then let's just shut down this site and all leave our cars bone stock and be done with it.
07-05-2005 | 09:46 PM
#32
My engine is in no shape or form stock. I have larger bore, stroke, cam, heads, but perhaps most important ti this particular discussion: larger ring gaps. This means more crankcase pressure and blowby(by design). I've already stated I wanted more area to vent crankcase pressure. Running the breather and PCV the way I have stated cures this problem and does not affect engine performance negatively at idle, WOT or anywhere in between. The stock PCV system is not adequate for my application. It is barely adequate for stock. The PCV fresh air intake hose on my V6 truck is at least 2 times larger than the stock fresh air hose on my Camaro was.
If you feel the PCV system is not up to snuff you have 2 good options IMO. Plug the entire PCV system all together and run just a breather, or run a vaccum pump. You stated that you don't want to run just a breather so the next best option would be a vaccum pump. The way you have it set up now has created an unmetered vaccum leak.
I believe I've already stated that I DO indeed have a vaccum leak only it's not an uncontrolled, erratic, untuned, performance disturbing leak. I think I've also tried to explain more than once that a PCV system is basicly a controlled, tuned, vacuum leak.
I'm sorry, but a correctly working PCV system is in no way, shape, or form, a vaccum leak. What you have now, however, is.
Well then let's just shut down this site and all leave our cars bone stock and be done with it.
Now, now, now. This is a great site for tech info, and it here to help members learn valuable info and maybe even prevent someone from doing something they shouldn't.
If you feel the PCV system is not up to snuff you have 2 good options IMO. Plug the entire PCV system all together and run just a breather, or run a vaccum pump. You stated that you don't want to run just a breather so the next best option would be a vaccum pump. The way you have it set up now has created an unmetered vaccum leak.
I believe I've already stated that I DO indeed have a vaccum leak only it's not an uncontrolled, erratic, untuned, performance disturbing leak. I think I've also tried to explain more than once that a PCV system is basicly a controlled, tuned, vacuum leak.
I'm sorry, but a correctly working PCV system is in no way, shape, or form, a vaccum leak. What you have now, however, is.
Well then let's just shut down this site and all leave our cars bone stock and be done with it.
Now, now, now. This is a great site for tech info, and it here to help members learn valuable info and maybe even prevent someone from doing something they shouldn't.
07-06-2005 | 12:01 PM
#34
If you feel the PCV system is not up to snuff you have 2 good options IMO. Plug the entire PCV system all together and run just a breather, or run a vaccum pump. You stated that you don't want to run just a breather so the next best option would be a vaccum pump. The way you have it set up now has created an unmetered vaccum leak.
You're right again it is a vacuum leak but it is definitely not unmetered. I quote directly from volume 3 of my GM service manual page 6-1893:
"The PRIMARY control(of PCV airflow) is through the crankcase ventilation valve(PCV valve) which METERS the flow at at rate depending on manifold vacuum". Nowhere in that article was the MAF sensor mentioned. Because the tiny bit of air at idle that is siphoned thru that ridiculously small 1/8" fresh air hose is practically irrelevant to the MAF sensor.
Secondly, If I wanted to run a vacuum pump I would. My car is not primarily a race car and the system I have works wonderfully. I may in the future add some type of vacuum pump system, but at this point it's not worth it to me in expense, hassle or engine compartment clutter.
I'm sorry, but a correctly working PCV system is in no way, shape, or form, a vaccum leak. What you have now, however, is.
This discussion is the sorry one. I'll let the GM service manual quote rest my case.
Now, now, now. This is a great site for tech info, and it here to help members learn valuable info and maybe even prevent someone from doing something they shouldn't.
Haahaha..Nice try but I am in no way advocating closure of this site. On the contrary I think maybe you and Santino should start "LS1Bonestock.com". Well I've enjoyed this friends, but I think I'll heed WILWAXU's hint and end this debate. Good day to you all.
You're right again it is a vacuum leak but it is definitely not unmetered. I quote directly from volume 3 of my GM service manual page 6-1893:
"The PRIMARY control(of PCV airflow) is through the crankcase ventilation valve(PCV valve) which METERS the flow at at rate depending on manifold vacuum". Nowhere in that article was the MAF sensor mentioned. Because the tiny bit of air at idle that is siphoned thru that ridiculously small 1/8" fresh air hose is practically irrelevant to the MAF sensor.
Secondly, If I wanted to run a vacuum pump I would. My car is not primarily a race car and the system I have works wonderfully. I may in the future add some type of vacuum pump system, but at this point it's not worth it to me in expense, hassle or engine compartment clutter.
I'm sorry, but a correctly working PCV system is in no way, shape, or form, a vaccum leak. What you have now, however, is.
This discussion is the sorry one. I'll let the GM service manual quote rest my case.
Now, now, now. This is a great site for tech info, and it here to help members learn valuable info and maybe even prevent someone from doing something they shouldn't.
Haahaha..Nice try but I am in no way advocating closure of this site. On the contrary I think maybe you and Santino should start "LS1Bonestock.com". Well I've enjoyed this friends, but I think I'll heed WILWAXU's hint and end this debate. Good day to you all.
