PCV Delete Guys - Problems Running Just Breathers?
I'm posting my point of view on things with facts about how these motors were designed to support my pov. You guys just say we're pushing parts and can't read but put no substance behind your methods other than your internet credibility.
Once I get the sled back together, I'm looking to run 8.50 index stuff anywhere I can, if Atco's got it I'll be there, especially if their race days is saturday or sunday, that's alot easier for me to make.
Believe me, I'd love to just leave the exhuast off the car. I have to redo it again I think with oval pipe this time to get it around some of the under car bars that will be there I think... makes for a pita.
Doesn't matter in the long run for this topic as I'm going to put a pump on the car. Probably be the only thing running off the crank pulley other then the external ignition wheel, maybe a dry sump.. if I can come up with the extra 3500
Believe me, I'd love to just leave the exhuast off the car. I have to redo it again I think with oval pipe this time to get it around some of the under car bars that will be there I think... makes for a pita.
Doesn't matter in the long run for this topic as I'm going to put a pump on the car. Probably be the only thing running off the crank pulley other then the external ignition wheel, maybe a dry sump.. if I can come up with the extra 3500
One breather is fine. As stated before, with bay to bay breathing, it is more than enough. Here is what I used for my 02 SS:
Metco breather to replace passenger side oil cap (TR sells them)
plug for drivers side grommet, GM part # 12568011
three 11/32 caps for the passenger side valve cover and throttle body
1 cap (can't remember size) for the intake manifold
Metco breather to replace passenger side oil cap (TR sells them)
plug for drivers side grommet, GM part # 12568011
three 11/32 caps for the passenger side valve cover and throttle body
1 cap (can't remember size) for the intake manifold
yeah that'd be nice. i also got a oil filler cap and filter so i can drill into the into the cap and push in the filter. so i dont have to pay for the 40 dollar metco filter.
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This sounds a lot like what a catch can does....
You're posting conflicting concepts. At one point you're saying breathers are fine because the pcv system is crap and then you're saying a vacuum pump is the best. PCV uses vacuum to evacuate pressure so I don't get it. I get that you don't want to hook any system up to your intake to avoid oil getting into the intake but you're making arguements about how and why things work, yet you're contradicting your own arguements about what's better.
Again conflicting statements.
You guys are comparing tearing down purpose built race motors to factory street motors and you can't really do that in this case. Race motors by nature are going to be much cleaner than a street motor because the race motor sees much higher cylinder pressures, heat, etc. than the street motor putting around under 3k rpm and sitting in traffic allowing carbon and everything else to build up. You also need to remember that ls1's are built with small, low tension rings which by design need a pcv system to help them seal better and not get beat up. You want more pressure above the ring than below it because with the low tension rings that pressure above will help them seal, think almost like a diesel. So when you're putting around at low rpm, drawing vacuum you're helping the rings do their jobs and live longer. This is why pcv is important. As far as cutting oil down going into the intake, I have seen quality catch cans significantly cut down or eliminate this. Feel free to look at my website, I don't have catch cans listed there so I'm not sitting here "pushing catch cans" but I AM PUSHING PCV SYSTEMS and running the motor the way the engineers at gm designed it to.
You're posting conflicting concepts. At one point you're saying breathers are fine because the pcv system is crap and then you're saying a vacuum pump is the best. PCV uses vacuum to evacuate pressure so I don't get it. I get that you don't want to hook any system up to your intake to avoid oil getting into the intake but you're making arguements about how and why things work, yet you're contradicting your own arguements about what's better.
Again conflicting statements.
You guys are comparing tearing down purpose built race motors to factory street motors and you can't really do that in this case. Race motors by nature are going to be much cleaner than a street motor because the race motor sees much higher cylinder pressures, heat, etc. than the street motor putting around under 3k rpm and sitting in traffic allowing carbon and everything else to build up. You also need to remember that ls1's are built with small, low tension rings which by design need a pcv system to help them seal better and not get beat up. You want more pressure above the ring than below it because with the low tension rings that pressure above will help them seal, think almost like a diesel. So when you're putting around at low rpm, drawing vacuum you're helping the rings do their jobs and live longer. This is why pcv is important. As far as cutting oil down going into the intake, I have seen quality catch cans significantly cut down or eliminate this. Feel free to look at my website, I don't have catch cans listed there so I'm not sitting here "pushing catch cans" but I AM PUSHING PCV SYSTEMS and running the motor the way the engineers at gm designed it to.
TECH Regular
Joined: Jul 2011
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Only way to know for sure would be to put a vacuum gauge tap in to the crankcase and test.
Of course, once the throttle is opened up more and more, the crankcase produces more pressure from increased blow-by and the manifold vacuum level drops, so the crankcase pressure then increases.
The only thing that it really does is evac what could be released into the atmosphere, but instead of doing it into the air it does it into the intake and therefore gunking up the top end of your motor, which is bad no matter how you look at it.
There is some suction/vacuum effect by hooking it up to the intake manifold, but not enough to make the pcv work anywhere near like a vacuum pump will.
I'll vent into the atmosphere all day long and feel good doing that vs putting all that into the intake manifold and into the ports, back side of the intake valves, etc.
I should have taken pictures of the top end of my old 402 after being raced for 2 years, and vented to the atmosphere. The intake ports were spotless, intake was spotless as well. You'd think the engine was just started up a couple times. Had I left a PCV on there, it would have for sure been a mess like eery street car I've ever taken apart for the first time.
As for the ring seal, I 100% agree that a vacuum pump helps this. But, the limited vacuum that a pcv creates, is not enough to make it's bad side effects, worth while.
There is some suction/vacuum effect by hooking it up to the intake manifold, but not enough to make the pcv work anywhere near like a vacuum pump will.
I'll vent into the atmosphere all day long and feel good doing that vs putting all that into the intake manifold and into the ports, back side of the intake valves, etc.
I should have taken pictures of the top end of my old 402 after being raced for 2 years, and vented to the atmosphere. The intake ports were spotless, intake was spotless as well. You'd think the engine was just started up a couple times. Had I left a PCV on there, it would have for sure been a mess like eery street car I've ever taken apart for the first time.
As for the ring seal, I 100% agree that a vacuum pump helps this. But, the limited vacuum that a pcv creates, is not enough to make it's bad side effects, worth while.
The only time the stock PCV system could possibly cause a slight vacuum in the crankcase is during idle or very low throttle openings ... which causes the highest vacuum level on the manifold, which is sucking on the crankcase. It also depends on how much blow-by is going on under this condition.
Only way to know for sure would be to put a vacuum gauge tap in to the crankcase and test.
Of course, once the throttle is opened up more and more, the crankcase produces more pressure from increased blow-by and the manifold vacuum level drops, so the crankcase pressure then increases.
Only way to know for sure would be to put a vacuum gauge tap in to the crankcase and test.
Of course, once the throttle is opened up more and more, the crankcase produces more pressure from increased blow-by and the manifold vacuum level drops, so the crankcase pressure then increases.
I tried the vacuum ga. hooked up to the crankcase on a car once.. at idle, and under 25% throttle it had minimal vacuum... very minimal vacuum. As soon as you put your foot into it at all the ga read pressure. And the vacuum that it did have at low engine speeds, was very limited, no way it was enough to ensure all the contaminents were leaving the crankcase. But, I do guarintee that it was enough to dirty up the intake, as we pulled the intake on that car after about 10K of driving (new intake on the car) and sure enough, it was in the process of becoming a mess.
TECH Regular
Joined: Jul 2011
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This is exactly why a race engine doesn't need a PCV, it's only idling, and essentially seeing a WOT situation. With the WOT being as much or more of the time.. the pressure is forcing the comtaminents out. Hence, why a vented crankcase is a better deal then a pcv on a drag engine... no contaminents being pumped into the intake by the crankcase pressure, dirtying up the air/fuel charge.
After 5 years this is still going on wow I remember reading this back in 2006...Read this on PCV then make your own informed decisions.
http://en.wikipedia.org/wiki/Crankca...ilation_system
All I have to say is that if the government didn't require U.S car companies to have a PCV system, do you really think they would go out of their way to have them? If you answer yes to that I will give you my paypal account and you can give me some money too...
http://en.wikipedia.org/wiki/Crankca...ilation_system
All I have to say is that if the government didn't require U.S car companies to have a PCV system, do you really think they would go out of their way to have them? If you answer yes to that I will give you my paypal account and you can give me some money too...
TECH Regular
Joined: Jul 2011
Posts: 452
Likes: 2
Car manufactures didn't design the PCV system for lots of WOT action, and apparently don't care if the intake system gets flooded with oil or not. So as need4fun said above, most of them are flawed in that respect. People try to prevent oil from contamination the intake system, which is the major result of the design flaw.
The only time the stock PCV system could possibly cause a slight vacuum in the crankcase is during idle or very low throttle openings ... which causes the highest vacuum level on the manifold, which is sucking on the crankcase. It also depends on how much blow-by is going on under this condition.
Only way to know for sure would be to put a vacuum gauge tap in to the crankcase and test.
Of course, once the throttle is opened up more and more, the crankcase produces more pressure from increased blow-by and the manifold vacuum level drops, so the crankcase pressure then increases.
Only way to know for sure would be to put a vacuum gauge tap in to the crankcase and test.
Of course, once the throttle is opened up more and more, the crankcase produces more pressure from increased blow-by and the manifold vacuum level drops, so the crankcase pressure then increases.
Staging Lane
Joined: Apr 2007
Posts: 78
Likes: 0
Glad I found this thread as I had my own little one started.
So is there a vented cap made that is ONE WAY so it vents under pressure but seals up under crankcase vacuum? Leaving the pcv system in place.
Thanks.
So is there a vented cap made that is ONE WAY so it vents under pressure but seals up under crankcase vacuum? Leaving the pcv system in place.
Thanks.
You will never have a crankase vacuum situation unless you put a vacuum pump on the engine. That being said, there is no vented cap that will only allow pressure to be released that I have seen.
Staging Lane
Joined: Apr 2007
Posts: 78
Likes: 0
This is on a STOCK LS6 type motor.
You are clearly saying this is not the case.
Back to square one.
But thanks much for the post.
