LS2 PCV Delete???
10-18-2006, 03:16 PM
#1
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LS2 PCV Delete??? Has anyone done or reccomends a PCV delete on a LS2?
I was thinking about putting a breather on the passenger valve cover and capping everything else...
I am worried about the crank case though.... Right now I have a catch can setup in between the crank case hose and intake and oil is collected in the can... If there is no longer a vaccum on the crankcase is that a bad thing?
Would it be ok to put a PCV valve on the crancase? That way pressure can get out but air can not be sucked in? Thanks guys!
I was thinking about putting a breather on the passenger valve cover and capping everything else...
I am worried about the crank case though.... Right now I have a catch can setup in between the crank case hose and intake and oil is collected in the can... If there is no longer a vaccum on the crankcase is that a bad thing?
Would it be ok to put a PCV valve on the crancase? That way pressure can get out but air can not be sucked in? Thanks guys!
10-19-2006, 01:35 AM
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Completely blocking off the LS2's PCV system isn't smart as you want the air inside the motor cleaned out every now and then as it helps remove condesnation and other material.
What about putting a reducer in the connection at the intake tube side.
This should reduce the vacuum level inside the vacuum hose itself.
In other words: by having the hose's inside diamater larger then the opening in the intake tube the vacuum level should be reduced.
It would be reversed if the opening was normal size and the hose's inside diamater were reduce it would cause an increase in the vacuum level.
What about putting a reducer in the connection at the intake tube side.
This should reduce the vacuum level inside the vacuum hose itself.
In other words: by having the hose's inside diamater larger then the opening in the intake tube the vacuum level should be reduced.
It would be reversed if the opening was normal size and the hose's inside diamater were reduce it would cause an increase in the vacuum level.
10-19-2006, 08:07 AM
#3
This is a much debated issue.
Getting the right mix of evacuation without sucking into the intake is the challange.
The LS2 valley (which has restriction) to intake tube will suck oil under heavy decell. The latest factory LS2s have a PCV valve between valve cover and air bridge.
I have tried every variation with LS1/6/2 and have not found the right combination.
Getting the right mix of evacuation without sucking into the intake is the challange.
The LS2 valley (which has restriction) to intake tube will suck oil under heavy decell. The latest factory LS2s have a PCV valve between valve cover and air bridge.
I have tried every variation with LS1/6/2 and have not found the right combination.
10-19-2006, 08:56 AM
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Originally Posted by See5
This is a much debated issue.
Getting the right mix of evacuation without sucking into the intake is the challange.
The LS2 valley (which has restriction) to intake tube will suck oil under heavy decell. The latest factory LS2s have a PCV valve between valve cover and air bridge.
I have tried every variation with LS1/6/2 and have not found the right combination.
Getting the right mix of evacuation without sucking into the intake is the challange.
The LS2 valley (which has restriction) to intake tube will suck oil under heavy decell. The latest factory LS2s have a PCV valve between valve cover and air bridge.
I have tried every variation with LS1/6/2 and have not found the right combination.
Question: I understand the intake is ALWAYS pulling a vacuum on the crank case...
Well is the crank case under any pressure? If it is under some amount of pressure you would think that you could put a PCV valve and breather on the valley cover opening and it would vent itself... (That way air would only exit the crank case and not be introduced.)
But you said there already is a PCV valve in the valley cover? Interesting... I will have to give it the "blow" test when I get home.
If I am not able to blow air into the intake (this meaning it does already have a PCV valve) then what do you think about just putting a 3/8" hose with a breather attached to the end of it on the valley cover?
10-19-2006, 09:50 AM
#5
The vacumn is increased from the valley on decell because it sucks from behind the ~closed TB. Not as true for the valve cover to TB line.
The newer than ~01 PCV valves are not check valves just restrictors.
The LS6 valley cover had wide open vent while the LS2 is significantly restricted and has rather intricate baffles on underside.
There have been numerous factory setups since 97 some with PCV valves some not. The later seem to rely on the valley cover and vent the crankcase via valve covers.
A catch can is really essential in my oppinion. This needs to go between valley and intake. It will catch a significant amount of oil headed for the intake. Not sure how to stop it rather than catch it.
The newer than ~01 PCV valves are not check valves just restrictors.
The LS6 valley cover had wide open vent while the LS2 is significantly restricted and has rather intricate baffles on underside.
There have been numerous factory setups since 97 some with PCV valves some not. The later seem to rely on the valley cover and vent the crankcase via valve covers.
A catch can is really essential in my oppinion. This needs to go between valley and intake. It will catch a significant amount of oil headed for the intake. Not sure how to stop it rather than catch it.
10-19-2006, 10:01 AM
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Originally Posted by See5
The vacumn is increased from the valley on decell because it sucks from behind the ~closed TB. Not as true for the valve cover to TB line.
The newer than ~01 PCV valves are not check valves just restrictors.
The LS6 valley cover had wide open vent while the LS2 is significantly restricted and has rather intricate baffles on underside.
There have been numerous factory setups since 97 some with PCV valves some not. The later seem to rely on the valley cover and vent the crankcase via valve covers.
A catch can is really essential in my oppinion. This needs to go between valley and intake. It will catch a significant amount of oil headed for the intake. Not sure how to stop it rather than catch it.
The newer than ~01 PCV valves are not check valves just restrictors.
The LS6 valley cover had wide open vent while the LS2 is significantly restricted and has rather intricate baffles on underside.
There have been numerous factory setups since 97 some with PCV valves some not. The later seem to rely on the valley cover and vent the crankcase via valve covers.
A catch can is really essential in my oppinion. This needs to go between valley and intake. It will catch a significant amount of oil headed for the intake. Not sure how to stop it rather than catch it.
I currently have a catchcan, but they are not 100% efficient...
Oil still gets in the intake and ends up in the heads...
I am just trying to figure out if a vacuum on the valley cover is necessary.
If I could leave the valley cover PCV open to atmosphere that would stop oild from getting in the intake and still be able to vent the crankcase?
10-19-2006, 10:21 AM
#7
Originally Posted by AppleMac
I currently have a catchcan, but they are not 100% efficient...
Oil still gets in the intake and ends up in the heads... Yes
I am just trying to figure out if a vacuum on the valley cover is necessary. Not sure but I bet there is more than the PCV resticted valve cover line can handle.
If I could leave the valley cover PCV open to atmosphere that would stop oild from getting in the intake and still be able to vent the crankcase?
Once you open ths system to atmosphere you loose control of the pressure/vac balance within the block. I tried a breather on the oil fill and it puked oil out under braking (I think) and it ran down over the headers so as to really upset those behind me. Gave up on that.
Oil still gets in the intake and ends up in the heads... Yes
I am just trying to figure out if a vacuum on the valley cover is necessary. Not sure but I bet there is more than the PCV resticted valve cover line can handle.
If I could leave the valley cover PCV open to atmosphere that would stop oild from getting in the intake and still be able to vent the crankcase?
Once you open ths system to atmosphere you loose control of the pressure/vac balance within the block. I tried a breather on the oil fill and it puked oil out under braking (I think) and it ran down over the headers so as to really upset those behind me. Gave up on that.
Last edited by See5; 10-19-2006 at 10:41 AM.
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10-19-2006, 03:52 PM
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Originally Posted by See5
Most recently SDPC told me to close off the valley cover and run a PCV valve off the left valve cover to the TB. When I questioned the logic of that I did not get a warm feeling. I suspect you would have a pressurized crankcase. Particularly with a stroker and in light of more people using an actual vac pump. I will likely try it though.
I was thinking about that... Is the pump powered by electricity or belt?
Where can you get one? And will it hold up to the oil? (I would guess you would still put a catch can in front of it... but some might still get through)
10-20-2006, 05:17 PM
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The larger the engine the more crankcase pressure you will have. The reason most of the LS1 cars get oil in the intake is because the port on the pcv valve is huge and basically tries to suck the engine dry. GM released a new pcv valve that has a small fixed orifice so it will not pull oil into the intake. This valve is for the older design valve covers with the valve on the drivers side rear. If you have LS2 valve covers, they have a fixed pcv fitting in the drivers side cover. You can use this in conjunction with the vent in the valley or just by itself. The more evacuation you have, the better off you will be. If you use the breather setup with no evac system it will most likely just blow all of the oil out of the breathers as the pressure builds.
FYI, the pcv part # is 12572717
FYI, the pcv part # is 12572717
10-20-2006, 06:28 PM
#11
Originally Posted by bg-sdpc
The larger the engine the more crankcase pressure you will have. The reason most of the LS1 cars get oil in the intake is because the port on the pcv valve is huge and basically tries to suck the engine dry. GM released a new pcv valve that has a small fixed orifice so it will not pull oil into the intake. This valve is for the older design valve covers with the valve on the drivers side rear. If you have LS2 valve covers, they have a fixed pcv fitting in the drivers side cover. You can use this in conjunction with the vent in the valley or just by itself. The more evacuation you have, the better off you will be. If you use the breather setup with no evac system it will most likely just blow all of the oil out of the breathers as the pressure builds.
FYI, the pcv part # is 12572717
FYI, the pcv part # is 12572717
The valley vent is now heavily restricted as is the PCV, so less evacuation does not relieve more pressure? Does it?
10-20-2006, 07:10 PM
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Originally Posted by See5
Well if there is more crankcase pressure with a 402>366>346 (agreed) for a couple reasons, wouldn't you need more need more evacuation than stock?
The valley vent is now heavily restricted as is the PCV, so less evacuation does not relieve more pressure? Does it?
The valley vent is now heavily restricted as is the PCV, so less evacuation does not relieve more pressure? Does it?
10-20-2006, 07:32 PM
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Originally Posted by See5
One breather on the valve cover will do it but it will probably be messy.
The automakers have to run a closed system.
The automakers have to run a closed system.
Yah, I understand that b/c of emissions.
Not too worried about a mess... I could always run a hose from the valve cover too underneath the motor and let it dump out down there...
10-21-2006, 11:09 AM
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The diesel engine in the Dodge Trucks used to have theirs setup that way. The hose run from the valve cover to underneath the motor. Only problem with that would be the underside of your car would be filthy. The dry sump of the LS7 is probably the best setup as it puts a vaccum on the engine as it is trying to suck the oil out. I am not positive but it probably has its downfalls as well. just my .02
10-21-2006, 07:20 PM
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Originally Posted by Dragaholic
Routing the oil to the underside of the car also plays a hazard for a drag car because if the oil falls in the path of the rear tires, it could lose traction and that wouldn't be a pretty site.
10-21-2006, 11:22 PM
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Originally Posted by Dragaholic
I know there's not much oil that would be passed down as I used to have a catch can on my old setup and even after several passes down the track, there would only be a few drops of oil caught in the can.It was a good point though... There is always a downdie to everything... Just gotta weigh the good vs bad...
04-17-2013, 09:38 PM
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On my c5, heads, can, hedders and intake. I deleted my PVC. Just plugged all the lines and put a breather in place of the oil cap. Heady drag use, 145,000 miles, lots with the cam. Etc. Never had any issues, not even a mess. The crankcase just couldn't build any pressure with the breather in place. Never blew out oil or anything like that.
I'm about to do this to my c6 also.
When I installed my cam, there was heavy carbon on the pistons from oil thru the stock PVC system. Intake was caked, heads. That's alot of detonation, which is controlled by knock sensors. A well known tuner told me that much carbon can take 10% power away. I'm not going to let my ls2 get all nasty inside like that. I'll change my oil every 3000 miles instead of every 5000 miles. No biggie
I'm about to do this to my c6 also.
When I installed my cam, there was heavy carbon on the pistons from oil thru the stock PVC system. Intake was caked, heads. That's alot of detonation, which is controlled by knock sensors. A well known tuner told me that much carbon can take 10% power away. I'm not going to let my ls2 get all nasty inside like that. I'll change my oil every 3000 miles instead of every 5000 miles. No biggie
