CamT's build thread

The valve covers should be connected together and joined to the intake tube between the MAF and T-Body. The top of the catch can gets connected at the back of the manifold to the tube coming from the valley cover (as shown in post #3 of the link you mentioned).
I have my system setup like the LS6 configuration, per the image on my blog link (sorry can't link images right now).

I believe this is also in accordance with the LS engine installation instructions from GM (right side of pg2): https://www.chevrolet.com/content/dam/chevrolet/na/us/english/index/performance/resources/installation-guides/crate-engines/01-images/ls-engine-controller-kits-all-naturally-aspirated-non-e-rod-except-lc9.pdf

"There are two ports on the engine that make up the PCV system" ... "Left rear valve cover" ... "Top center of the inlet manifold" .. "the tubes have a small orifice within them that is used in place of a PCV valve" ...

"there is one fresh air port which is on the front of the right valve cover" ... "This port should be connected to filtered clean air... must be between the MAF and engine's throttle body" ...

Perhaps the difference is the image you're referencing is for an engine delivered in a vehicle vs a crate motor? (the GM instructions I linked are applicable to crate LS7s as well, at least the specific PN listed on pg1).
 

Ken Roberts

Supporter
The instructions from Elite for the LS1"late"/LS6"late"/LS2/LS3/LS7 configuration show the top barb on the catch can connecting with the valley cover port only. The diagram you referenced was drawn by some random guy on the internet.....not one of the Catch can manufacturers. Most OEM LS engines have the left side valve cover port blanked off. The only car I know that uses the left side port is the LS7 and LS9 engines. Those two have both right and left valve cover ports tied together and then joining with the intake tube after the MAF. Both valve cover ports are fresh air "in". They more than likely use the two entry points for fresh metered air due to the extra blow by created in severe duty. I would say the crate motor instructions are wrong. I would follow the instructions of the catch can manufacturer and OEM over the crate motor instructions.

The crate motor instructions also tell you to mount the maf a minimum of 10" from the t body. Most OEM installations are much closer.
 
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The instructions from Elite for the LS1/LS2/LS3/LS7 configuration show the top barb on the catch can connecting with the valley cover port only. The diagram you referenced was drawn by some guy on the internet.....not one of the Catch can manufacturers. Most OEM LS engines have the right side valve cover port blanked off. The only car I know that uses the right side port is the LS7 and LS9 engines. Those two have both right and left valve cover ports tied together and then joining with the intake tube after the MAF. Both valve cover ports are fresh air "in". I would say the crate motor instructions are wrong. I would follow the instructions of the catch can manufacturer and OEM over the crate motor instructions.

The crate motor instructions also tell you to mount the maf a minimum of 10" from the t body. Most OEM installations are much closer.
Uuuh ... the diagram I referenced was drawn by the same guy you referenced ... :confused: Aaron M Anderson - "some guy on the internet"

I don't know who Elite Engineering is, and how they're tied in with GM, but I suspect GM knows more about their engines than Elite does. I'd say the instructions from Elite are generic whereas the GM instructions are specific, so to choose one over the other when there's a discrepancy, the choice for me would be to side with the specific. I suppose if Elite's instructions also included "we know GM's crate motor instructions are WRONG, follow these instructions or your engine will blow up" then I'd pay more heed.

With respect to the crate motor instructions and the MAF - the crate motor instructions here are the generic, they're telling you that not knowing what the rest of the intake system's going to look like. With GM vehicle-specific applications, the air boxes/intake tracts are designed with plenty of CFD and testing to ensure the MAF is getting clean stabilized airflow before and after the sensor (or their tables are built with some compensation factor). I'm not sure that's a valid argument for tossing GM's instructions.

Agree to disagree I guess.
 

Dan Carter

Supporter
Cam and or Joel

Do either of you have a schematic for the intended LS setup you can share. Now I’m curious if mine is correct.

Thanks
 

Ken Roberts

Supporter
I used his drawing for the LS7 engine because it was correct and easy to understand. I would trust GM OEM installation in millions of cars over GM crate motor instructions. As a side note I have found many many errors in factory OEM GM service manuals over the years. The worst ones are where they mix up inch pounds and foot pounds.

In your configuration the bulk of the dirty air will be pulled from the one valve cover area. Not much will be pulled from the valley cover as GM intended due to it being much farther down the line. The valley cover orifice tube is chosen due to it's central location and a larger cavity. The bottom of the valley cover also has a specially made trap for oil vapors.

In addition this is part of the idle air that is metered and bypassing the throttle body blade when closed. Poor low speed performance could be affected. Just a heads up if you have idle or stalling issues in the future.
 

Roger Reid

Supporter
My engine builder (Late Model Engines) told me to connect both valve cover vents with a T and connect to the catch can. No connection from the valley cover to the catch can. I can see an OEM connecting the gasses to the intake as not to have a catch can. Most drivers don't want the hassle of draining the catch can as a regular service item.
 

Ken Roberts

Supporter
This drawing is correct although it is showing a LS1 throttle body. The colored line looks like it is entering behind the throttle body but on that style of throttle body the line travels through a passage in the throttle body and is actually in front of the throttle body blade (like a LS3). You can connect both valve covers together as in the drawing or just the one on the left side of the picture. The other one cannot be left open. It must be sealed.

Perhaps we should start a new thread instead of mucking up Cams build log.
LS7 Wet Sump-No_CC.jpg
 
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I used his drawing for the LS7 engine because it was correct and easy to understand. I would trust GM OEM installation in millions of cars over GM crate motor instructions. As a side note I have found many many errors in factory OEM GM service manuals over the years. The worst ones are where they mix up inch pounds and foot pounds.

In your configuration the bulk of the dirty air will be pulled from the one valve cover area. Not much will be pulled from the valley cover as GM intended due to it being much farther down the line. The valley cover orifice tube is chosen due to it's central location and a larger cavity. The bottom of the valley cover also has a specially made trap for oil vapors.

In addition this is part of the idle air that is metered and bypassing the throttle body blade when closed. Poor low speed performance could be affected. Just a heads up if you have idle or stalling issues in the future.
Yeah, appreciate your input but we'll just have to agree to disagree on this point. Both the valley and valve cover ports are orificed, it's very specific in the instructions on this matter. Without knowing precisely what the orifice sizes are and what the pressure is in their respective cavities, you can't really say which port is going to flow more.

Similarly, the diagram I used was for convenience, not because it's any more right or wrong than the one you've posted. However, the schematic I posted in my blog corresponds to the correct routing per GM's crate motor instructions. GM OEM installation in millions of cars has nothing to do with how they setup their crate motors so I don't see how you'd use that to discount their very explicit instructions. All LS3 crate motors are shipped with the Camaro style oil pan - does that mean every LS3 engine shipped with cars uses the same oil pan? Seems a bit silly when I try to use that same logic going in the other direction.

Dan - here's the schematic I followed:



Roger - generally you want an IN and OUT flow of air for your PCV, otherwise you may subject your crankcase to excessive vacuum (assuming your catch can is a closed loop system and not just vented to atmosphere). Regardless, I'd go with whatever your engine builder recommended you do as they're most familiar with how that engine is built.
 

Ken Roberts

Supporter
Just read what it said about the PCV system in the crate motor instructions. Do you realize they are describing the LS truck manifold PCV system.....lol:rolleyes:

The first give away is the left rear valve cover location and the second give away is the top center of inlet manifold. Here is a picture of what they are describing.

0996b43f81b05d8b.gif
 
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lol, I admire your tenacity Ken!

GM probably sells more truck based LS motors than they do car based LS motors. So it stands to reason that their truck valve covers are probably less expensive than their car valve covers from a volume discount perspective.

Let me draw out 2 scenarios for you and you can tell me what you think:

Scenario 1:
Engineer: Hey Boss! We need to decide which valve covers we're going to use on all our crate motors, what do you think?
Boss: Dummy, use the truck valve covers, they're cheaper.
Engineer: You got it boss! Hey, the Instructions Guys want us to say something about the PCV system, what should I say?
Boss: It's a truck valve cover right? Use what the truck guys use!
Engineer: You got it boss!

Scenario 2:
Engineer: Hey Boss! We need to decide which valve covers we're going to use on all our crate motors, what do you think?
Boss: I don't care, I'm drinking my coffee - you decide!
Engineer: You got it boss! Hey, the Instructions Guys want us to say something about the PCV system, what should I say?
Boss: We sell a lot of trucks right? Use what the truck guys use!
Engineer: But boss, those instructions reference PCV being at the top of the intake manifold and the left valve cover - none of our crate motors have PCV ports at these locations!
Boss: Dummy, no one reads these instructions anyway! Now go away, I'm trying to enjoy my coffee!
Engineer: You got it boss!

Now of those 2 scenarios, which of the 2 takes the smaller leap to best match up with what we're discussing today?

This is your rationale for why you think your routing is "correct":

"I would trust GM OEM installation in millions of cars over GM crate motor instructions. As a side note I have found many many errors in factory OEM GM service manuals over the years. The worst ones are where they mix up inch pounds and foot pounds."

I just don't think there's enough weight behind what you've said to convince me the instructions are wrong (despite finding what you did about the truck intake). I don't think you've actually reviewed millions of OEM installations, you've looked at a handful of engines in cars and they were all the same - no PCV out on the valve cover. It's a pretty big leap then to say that all PCV systems are designed the same - in part because you've already found evidence to the contrary. So unless you've pulled the valley and valve covers off an LS3 motor and measured the diameters at each location to show that indeed, the left and right valve covers have identical passage sizing and only the valley has an orifice ... I gotta go with GM on this one.

1 - we know with absolute certainty that the port sticking up from the valley should be PCV outlet.
2 - you've now established that there absolutely are valve cover designs that are part of the PCV system and that they should be connected to PCV out
3 - It's just PCV dude, let's just agree to disagree. You can go around telling everyone there's this crazy guy named CamT who has his PCV setup totally wrong and that they should ignore the crate motor instructions.

Incidentally, the valve cover in that pic you've found of the truck setup looks exactly like the valve cover on my engine, FWIW.

Last bit regarding what you said about idle quality as I failed to acknowledge it earlier - these LS motors in our cars are notorious for poor idle quality, PCV setup correctly or not. The MAF measures incoming air ingestion at all conditions, idle included. The circuit I have setup pulls air from a location behind the MAF and therefore any air being ingested by the engine at idle has already been measured by the MAF. It's no different in your proposed circuit vs what I'm running. I will say that the little bit of driving I was able to do after moving my MAF sensor closer to the throttle body did seem to improve my idle quality - but I think that has more to do with pushing that sensor further from the air filter than I do bringing it closer to the throttle body (as my tuner suggested). So yes, crate motor instructions be damned!
 

Johan

GT40s Supporter
I used his drawing for the LS7 engine because it was correct and easy to understand. I would trust GM OEM installation in millions of cars over GM crate motor instructions. As a side note I have found many many errors in factory OEM GM service manuals over the years. The worst ones are where they mix up inch pounds and foot pounds.

In your configuration the bulk of the dirty air will be pulled from the one valve cover area. Not much will be pulled from the valley cover as GM intended due to it being much farther down the line. The valley cover orifice tube is chosen due to it's central location and a larger cavity. The bottom of the valley cover also has a specially made trap for oil vapors.

In addition this is part of the idle air that is metered and bypassing the throttle body blade when closed. Poor low speed performance could be affected. Just a heads up if you have idle or stalling issues in the future.

Ken, thanks a lot for this post. I finally figured out my poor idle quality. Since I have the Dailey dry sump system I blocked off all the PCV outlets and just running a vaccuum regulator on pax side valve cover. (Set to 12 inches)
I’ll try a 2,5 mm orifice at the TB inlet.
 

Ken Roberts

Supporter
Yes the valve covers are the same ...no issue with that. That is port number #1. Forget about concentrating on that aspect! Focus on the statement about the second port described in the crate motor instructions. They say it is located at the top center of the inlet manifold. They don't say it is metered/orifice! You assume it is a orifice and you also wrongly assume it is the valley cover. How do you account for that? That is not the valley cover. The port in the valley cover is at the front, not in the middle and not at the top. Rationalize that issue please! You have made a second "metered air" port where there is none.

Truck intakes have two PCV ports-
1- metered/orifice dirty air output from the crankcase (valve cover location).
2-Same metered air input to the intake manifold (top center of the intake manifold)

Car intakes have two PCV ports-
1- metered/orifice dirty air output from the crankcase (valley cover port).
2- metered air input to the intake manifold (front lower side of the intake manifold just behind the t body flange).

Cams' intake mysteriously has three PCV ports.
1- metered/orifice dirty air output from the crankcase (valley cover port).
2- metered/orifice dirty air output from crankcase (valve cover location).
3-Both of these are tee'd together to the metered air input to the intake manifold (front lower side of the intake manifold just behind the t body).

All three setups have a separate "fresh air" in at the other valve cover (metered by the maf).

Conclusion: The stock PCV system (truck, car or crate motor) does not use two metered/orifices. Give me one explanation why a crate motor would be any different and please try not to make me look like a moron? Too much "dirty air" is being needlessly removed from the crankcase and rerouted back into the intake air stream. Yes....this air is being metered by the MAF (needlessly). Could it lead to other issues.....possibly (especially low speed/idle operation) The MAF sensor is not some magical wand that will make it alright. The orifice is a precise size (2.5mm) for a reason. I'm holding one in my hand in the attached picture.

You keep referring to the "precise" instructions for the crate motor. All the instructions mention is there are two PCV ports and one fresh air port and not to modify the metered ports (silver tubes).

IMG_2525.JPG
 
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Ken - you're obviously pretty fired up so let me try to defuse things a little. I try to inject humor into most of the posts I make and perhaps the wording of my scenarios has struck a nerve with you - I certainly didn't intend to insult you in any way with my post. If that's the way you interpreted it then I am absolutely sorry that's how it came across.

I wanted to get that out first in case you feel I've insulted you.

Where we fundamentally disagree is you believe the crate motor instructions are wrong and I believe they are right. I think it's safe to say that's fact.

Here's a screen grab from the instructions in question:



My interpretation of these instructions is it does state there are 3 ports that are part of the PCV system. 2 are referenced in the first part of the instructions. The last sentence in the upper paragraph states "The TUBES have a small orifice within THEM that is used in place of a PCV valve of earlier designs." So my interpretation of that statement is that someone from GM explicitly states/believes there's more than one orifice in the particular system they are writing about.

The last paragraph goes on to mention that there is a THIRD tube that is part of the PCV system, and that this port is the source for fresh air (and should be connected after the MAF).

So that's how my engine ended up with 3 ports as part of the PCV system - the instructions told me so.

I know, you believe they're wrong and I believe they're right.

As far as rationalizing how the instructions got it wrong, I'm not - they got it wrong. They referred to the top of the intake manifold when they should have referred to the port in the valley. I kind of inferred that in my earlier post but maybe it was clear in my head and not in writing.

I think the horse died. :oops:
 

Ken Roberts

Supporter
Why doesn't it mention the PCV port in the front side of the intake manifold just behind the throttle body? Is that a second error you have chosen to overlook in their instructions?

I think it would be safe to say that others who read this exchange should call their help line to get to the bottom of it if they are confused by which is the correct way to hook up the PCV system.
 
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Roger Reid

Supporter
Not to beat a dead horse but as Harry Nielson says in the coconut song, "now let me get this straight". Manifold vacuum is the power source that causes all the air to move through the PCV circuit. This vacuum draws filtered air from a port after the MAF sensor but before the throttle body to one valve cover port. This air slowly flows through the crankcase picking up contamination caused by piston ring blow by and exits through ports in the valley cover and the other valve cover. This contaminated air flows from both the valley port and the other valve cover port to a tee combining both lines and then on to the catch can. The question is where is/are the 2.5 mm orifices. Before or after the tee. If there is only one line (from valley cover only) as per the dwg in post 329, there is only one 2.5 mm orifice. If there are two lines (from valve cover and valley cover) as per the dwg in post 330 there could be 2 orifices if before the tee or just one if after the tee. If there is just one 2.5 mm orifice after the tee or even after the catch can then both dwgs are in effect the same. If the 2.5 mm orifice is at the manifold there is just one which makes sense.
I appreciate this forum as I learn more about how things work. Not only that but because of repetition and spell check I learned how to spell orifice.
 
Why doesn't it mention the PCV port in the front side of the intake manifold just behind the throttle body? Is that a second error you have chosen to overlook in their instructions?

I think it would be safe to say that others who read this exchange should call their help line to get to the bottom of it if they are confused by which is the correct way to hook up the PCV system.
Apparently I fail at the art of de-escalation.

You got me Ken, I just assumed the port just behind the throttle body is where the PCV out was supposed to be plumbed. I guess if we're going to get technical then there are really 5 ports that comprise the entirety of the PCV system (on my crate engine); the instructions are explicit about 4 (it mentions the clean source air should be plumbed from a location of filtered air between the TB and MAF but doesn't use the term "port") but does fail to specify where the 2 orificed ports should be routed to, error #2. I don't think I'm glossing over or overlooking all that much with their instructions; I've acknowledged that they reference the top of the intake manifold when I really believe what they meant was the port located above the valley - we both agree that's an orificed PCV out location so no debate there. Otherwise I believe their instructions to be correct for my particular engine.

As I said before, I try to inject humor into my posts and if you interpreted it as anything otherwise I've already apologized. That's 2 apologies, next one comes with a big wet kiss (you know where).

I followed the instructions per my interpretation. I posted the instructions written by GM and I also walked through my thought process on how I arrived at that interpretation. You're countering based on experiential knowledge. I suppose you think I'm spreading misinformation but I don't think I am, and I've provided the supporting evidence for it. Anyone reading this thread can make up their mind as to what the proper routing should be - thank you for your input and for highlighting your concerns. I've said it a few times before, let's just agree to disagree.

And yes I agree, this exchange has gotten pretty muddled and if someone reading this is confused about how they should setup their PCV system, then absolutely, they should contact a specialist familiar with their engine. In all situations, not just PCV, if someone is unsure about what they should do with their car my advice would be to consult an actual expert, my Holiday Inn Express points mean nothing here.

Official disclaimer: For anyone reading this thread, please use your judgement on anything I've posted, I'm just some guy who knows a little bit about a little bit. I'm in no way an expert on most things related to building a car - this is my first project of this type and scope.

... must be one of those White Walker horses from Game of Thrones, just when you think it's dead it eats you! o_O (**this is purely meant for humor and to express my excitement about the coming GOT finale. This post has been written and thoroughly reviewed to ensure it is barb-free.)
 
I'm using a Mighty Mouse catch can. I hooked it up as per David Childress from Mighty Mouse. But I refuse to disclose the top secret hose routing he had me use on my LS3.
 
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