does LS3 have a internal PCV?
02-01-2009, 09:23 AM
#2
TECH Fanatic
iTrader: (9)
Join Date: Feb 2002
Location: Morton IL
Posts: 1,126
Likes: 0
Received 0 Likes
on
0 Posts
When engineers talk about "oil control", they mean control, not only in the oil pan, to keep the oiling system from sucking air, and control by piston ring and ring groove design; they mean oil control through the crankcase ventilation system, too. There are two sides to any PCV system, the "fresh side", where air goes into the crankcase and the "foul side," where dirty air comes out. On Gen 4 engines, both sides have oil separators. The foul side separator is the most important because that's where there is oil in the crankcase ventilation flow virtually all the time. Blow-by goes in the crankcase, through the foul-side separator then is consumed in the engine.
LS3 has a new design for that separator. It shares the same location as the LS1's, but internally, it's quite different. Once again, computational fluid dynamics played a part in development, but this time, with the addition of some proprietary GM software code called “Rain Drop Analysis”. CFD with RDA is able model the flow of air in which oil is suspended as it goes through separator. The data gained from that helped engineers develop baffles which would better separate the oil from the air. This unique oil/air separator design is so effective that it was patented. At the time rain drop analysis was paired with CFD for the initial Gen 4 development in 2002, it was a revolutionary computer modeling tool. Even today, few companies utilize it because of the immense computer power necessary to run it.
Ideally, you want to separate all the oil and return it to the crankcase and only have the engine ingest air and blow-by gases. In practice, you burn some oil, but it needs to be as little as possible. It there's too much oil in the PCV flow, oil consumption will rise. With the LS1, when there was a lot of air moving through the PVC system at high speed but the engine was only lightly loaded; the system wasn't efficient at separating the oil from the air, so those engines suffered higher oil consumption than engineers and some 4 Gen Camaro owners would have liked.
Not only does the LS3 have significant improvement in its foul-side, oil/air separator, it also has less blow-by air flow under those conditions. Less blow-by under high-rpm/light-load conditions and a more effective separator means less oil consumption.
At high-rpm and wide-open-throttle, blow-by flow can reach the capacity of the foul side. That capacity cannot be so large that it would never be exceeded because it's undesirable to constantly consume large quantities of crankcase air through the intake side of the engine. You want to consume only enough that you're constantly purging the crankcase vapors adequately. At light load, there is an assist from manifold vacuum which insures constant crankcase purging. That reduces sludge formation and burns hydrocarbon pollution.
At WOT, there is no vacuum to help pull the air from the crankcase and, also, there is more blow-by; so you exceed the flow capacity of the foul side, which is sized for most normal light load operation.
Often there is enough blow-by at WOT that the clean-side air flow reverses. If that happens, it might force oil into the intake. That's why Gen 4 has oil/air separation on both the clean and the foul sides.
LS3 has a new design for that separator. It shares the same location as the LS1's, but internally, it's quite different. Once again, computational fluid dynamics played a part in development, but this time, with the addition of some proprietary GM software code called “Rain Drop Analysis”. CFD with RDA is able model the flow of air in which oil is suspended as it goes through separator. The data gained from that helped engineers develop baffles which would better separate the oil from the air. This unique oil/air separator design is so effective that it was patented. At the time rain drop analysis was paired with CFD for the initial Gen 4 development in 2002, it was a revolutionary computer modeling tool. Even today, few companies utilize it because of the immense computer power necessary to run it.
Ideally, you want to separate all the oil and return it to the crankcase and only have the engine ingest air and blow-by gases. In practice, you burn some oil, but it needs to be as little as possible. It there's too much oil in the PCV flow, oil consumption will rise. With the LS1, when there was a lot of air moving through the PVC system at high speed but the engine was only lightly loaded; the system wasn't efficient at separating the oil from the air, so those engines suffered higher oil consumption than engineers and some 4 Gen Camaro owners would have liked.
Not only does the LS3 have significant improvement in its foul-side, oil/air separator, it also has less blow-by air flow under those conditions. Less blow-by under high-rpm/light-load conditions and a more effective separator means less oil consumption.
At high-rpm and wide-open-throttle, blow-by flow can reach the capacity of the foul side. That capacity cannot be so large that it would never be exceeded because it's undesirable to constantly consume large quantities of crankcase air through the intake side of the engine. You want to consume only enough that you're constantly purging the crankcase vapors adequately. At light load, there is an assist from manifold vacuum which insures constant crankcase purging. That reduces sludge formation and burns hydrocarbon pollution.
At WOT, there is no vacuum to help pull the air from the crankcase and, also, there is more blow-by; so you exceed the flow capacity of the foul side, which is sized for most normal light load operation.
Often there is enough blow-by at WOT that the clean-side air flow reverses. If that happens, it might force oil into the intake. That's why Gen 4 has oil/air separation on both the clean and the foul sides.
02-01-2009, 09:35 AM
#3
When engineers talk about "oil control", they mean control, not only in the oil pan, to keep the oiling system from sucking air, and control by piston ring and ring groove design; they mean oil control through the crankcase ventilation system, too. There are two sides to any PCV system, the "fresh side", where air goes into the crankcase and the "foul side," where dirty air comes out. On Gen 4 engines, both sides have oil separators. The foul side separator is the most important because that's where there is oil in the crankcase ventilation flow virtually all the time. Blow-by goes in the crankcase, through the foul-side separator then is consumed in the engine.
LS3 has a new design for that separator. It shares the same location as the LS1's, but internally, it's quite different. Once again, computational fluid dynamics played a part in development, but this time, with the addition of some proprietary GM software code called “Rain Drop Analysis”. CFD with RDA is able model the flow of air in which oil is suspended as it goes through separator. The data gained from that helped engineers develop baffles which would better separate the oil from the air. This unique oil/air separator design is so effective that it was patented. At the time rain drop analysis was paired with CFD for the initial Gen 4 development in 2002, it was a revolutionary computer modeling tool. Even today, few companies utilize it because of the immense computer power necessary to run it.
Ideally, you want to separate all the oil and return it to the crankcase and only have the engine ingest air and blow-by gases. In practice, you burn some oil, but it needs to be as little as possible. It there's too much oil in the PCV flow, oil consumption will rise. With the LS1, when there was a lot of air moving through the PVC system at high speed but the engine was only lightly loaded; the system wasn't efficient at separating the oil from the air, so those engines suffered higher oil consumption than engineers and some 4 Gen Camaro owners would have liked.
Not only does the LS3 have significant improvement in its foul-side, oil/air separator, it also has less blow-by air flow under those conditions. Less blow-by under high-rpm/light-load conditions and a more effective separator means less oil consumption.
At high-rpm and wide-open-throttle, blow-by flow can reach the capacity of the foul side. That capacity cannot be so large that it would never be exceeded because it's undesirable to constantly consume large quantities of crankcase air through the intake side of the engine. You want to consume only enough that you're constantly purging the crankcase vapors adequately. At light load, there is an assist from manifold vacuum which insures constant crankcase purging. That reduces sludge formation and burns hydrocarbon pollution.
At WOT, there is no vacuum to help pull the air from the crankcase and, also, there is more blow-by; so you exceed the flow capacity of the foul side, which is sized for most normal light load operation.
Often there is enough blow-by at WOT that the clean-side air flow reverses. If that happens, it might force oil into the intake. That's why Gen 4 has oil/air separation on both the clean and the foul sides.
LS3 has a new design for that separator. It shares the same location as the LS1's, but internally, it's quite different. Once again, computational fluid dynamics played a part in development, but this time, with the addition of some proprietary GM software code called “Rain Drop Analysis”. CFD with RDA is able model the flow of air in which oil is suspended as it goes through separator. The data gained from that helped engineers develop baffles which would better separate the oil from the air. This unique oil/air separator design is so effective that it was patented. At the time rain drop analysis was paired with CFD for the initial Gen 4 development in 2002, it was a revolutionary computer modeling tool. Even today, few companies utilize it because of the immense computer power necessary to run it.
Ideally, you want to separate all the oil and return it to the crankcase and only have the engine ingest air and blow-by gases. In practice, you burn some oil, but it needs to be as little as possible. It there's too much oil in the PCV flow, oil consumption will rise. With the LS1, when there was a lot of air moving through the PVC system at high speed but the engine was only lightly loaded; the system wasn't efficient at separating the oil from the air, so those engines suffered higher oil consumption than engineers and some 4 Gen Camaro owners would have liked.
Not only does the LS3 have significant improvement in its foul-side, oil/air separator, it also has less blow-by air flow under those conditions. Less blow-by under high-rpm/light-load conditions and a more effective separator means less oil consumption.
At high-rpm and wide-open-throttle, blow-by flow can reach the capacity of the foul side. That capacity cannot be so large that it would never be exceeded because it's undesirable to constantly consume large quantities of crankcase air through the intake side of the engine. You want to consume only enough that you're constantly purging the crankcase vapors adequately. At light load, there is an assist from manifold vacuum which insures constant crankcase purging. That reduces sludge formation and burns hydrocarbon pollution.
At WOT, there is no vacuum to help pull the air from the crankcase and, also, there is more blow-by; so you exceed the flow capacity of the foul side, which is sized for most normal light load operation.
Often there is enough blow-by at WOT that the clean-side air flow reverses. If that happens, it might force oil into the intake. That's why Gen 4 has oil/air separation on both the clean and the foul sides.
02-01-2009, 09:41 AM
#4
TECH Fanatic
iTrader: (9)
Join Date: Feb 2002
Location: Morton IL
Posts: 1,126
Likes: 0
Received 0 Likes
on
0 Posts
http://i2.photobucket.com/albums/y20...coverunder.jpg
correct, not like the old school external pcv's of old.
correct, not like the old school external pcv's of old.
02-01-2009, 10:40 AM
#5
That looks similar to the LS6 valley cover. So, this separator uses a fixed orifice somewhere inside of it?
You say old school external, but these are still widely in use and fixed orifice systems limit flow when its needed most.
Do you have any pics of the separator disassembled? Where is the fixed orifice in the valley cover?
You say old school external, but these are still widely in use and fixed orifice systems limit flow when its needed most.
Do you have any pics of the separator disassembled? Where is the fixed orifice in the valley cover?
02-01-2009, 11:02 AM
#6
TECH Apprentice
Thread Starter
iTrader: (1)
Join Date: Nov 2007
Location: illinois
Posts: 388
Likes: 0
Received 0 Likes
on
0 Posts
this is why I asked, I thought the LS6 had the same valley. Greg knows his stuff, so I do not doubt him..but it was odd to have Scoggin Dickey to tell me to add a valve in the plumbing. They said that maybe was the cause of my rings not seating
Trending Topics
02-05-2009, 03:49 PM
#9
http://i2.photobucket.com/albums/y20...coverunder.jpg
correct, not like the old school external pcv's of old.
correct, not like the old school external pcv's of old.
Where does the LS3 injest air from on the "fresh side"?? The LS1 has a short line running from the top side of the TB to the valve cover, is that good enough for a fresh side vent or should I be using a line somewhere else??
BTW, excellent info you have there.
02-05-2009, 04:15 PM
#10
On The Tree
iTrader: (5)
Join Date: Jun 2004
Location: Knoxville, TN
Posts: 195
Likes: 0
Received 0 Likes
on
0 Posts
Does the LS3 have the same setup as an L92 w/ VVT but w/o displacement on demand? What kind of PCV setup do I need to use with an L76 intake? Any difference if I use an LS3? Thanks.
02-05-2009, 07:28 PM
#12
10 Second Club
iTrader: (15)
Join Date: Nov 2001
Location: St. Michael, MN.
Posts: 4,519
Likes: 0
Received 0 Likes
on
0 Posts
That looks exactly like the LS2 valley cover which I believe is also used on the LS7. This cover has no provisions for knock sensors, so I'm pretty sure it won't work on a Gen III motor because of the baffle.
02-05-2009, 07:31 PM
#13
TECH Fanatic
iTrader: (9)
Join Date: Feb 2002
Location: Morton IL
Posts: 1,126
Likes: 0
Received 0 Likes
on
0 Posts
i'm almost certain they all share the same valley cover now. ie ls2/3/7.
not sure how the 'factory' installs are for the gen 4's. however
http://eliteengineeringusa.com/Insta...uctions_CC.pdf
on page 7 it shows how to hook it up with use of a catch can
not sure how the 'factory' installs are for the gen 4's. however
http://eliteengineeringusa.com/Insta...uctions_CC.pdf
on page 7 it shows how to hook it up with use of a catch can
