DH -- what year is your Vette? I thought you already had the fixed orifice valley cover ... maybe I'm thinking of someone else.

If SDPC sees a big difference with the fixed orifice PCV unit then it's worth a try IMO. I'm going to try one with just my EE catch can in the dirty line and see what happens. How much was it? ... can't be more than $5 I would imagine.

 

If you want to go even further, add a Watts F501-02DH coalescing filter to catch the aerosols that the EE can will inevitably let pass. This is the filter assembly without the bracket, which is not needed if you were to connect it to the EE with a 1/4 MNPT pipe-to-pipe fitting.

Howie, I too, thought you had an 04; wouldn't that have the small orifice, already?

 

I do have 2004, but this thing has a tiny little hole in it that isn't present on my setup!!!!. I don't even know how it hooks up??????


DH

 

I would consider doing that ... do you have a photo of the filter so I can see what it looks like and hooks up?

 

I think the 2004+ cars have the 2.5 mm (0.10 inch) orifice built into the PCV nose nipple coming off the right front corner of the valley cover.

 

Here's what I'm running right now. The standard Watts zinc housing is the black one. The aluminum one (my own design) doubles the reservior capacity, even though it is not nearly as large as some of the traditional catch cans. I am currently asking for a quote for a larger aluminum "can" (just finished the drawing), but if its cost is significantly higher than the one you see in this pic, I may not go that route. If you want to try the standard Watts (no mounting bracket), I believe they go for about $48 or so. The version that includes the bracket and mounting holes goes for $55.



Dave

 

Ok,
First, I don't disagree with ZeeO on the need for some way to reduce oil consumption or oil in the combustion process. I am not attempting to belittle the discussion, just exploring this with you guys. However, I think the intent, from a GM perspective is to consider that the PCV has two functions; it relieves internal combustion gases (here-to-for with vaccum) and, important to the manufacturer, more specifically to reduce emissions. To the point of ring seal or combustion gases; a couple of vents on the top of the engine or even a crankcase evap like that which drag racers used to use with tubes from the valve covers to the header collectors is sufficient. What LS enthusiests need is a system to relieve internal combustion gases without introducing excessive oil into the intake process. GM has evolved this from a variable PCV to a small orifice, to then, what my wife's CTS-V has, no PCV (but still crankcase ventilation).....the CTS-V LS2 has a tube which loops from the valley cover to the intake (behind the TB); then there is a small tube from the passenger side valve cover to the low side of the intake prior to the TB. This is the stock set up and the car does burn oil; about a quart every 5-6000 miles. I have emulated this set-up on my 418 L92 with higher compression, big street cam, and mods; it works well enough and I have no PCV. I will however add a catch can (when I drive the car more) for its obvious effectiveness. One last point regarding those concerned about emissions (of which I am not one), The OBDII ECM, in concert with modern fuel injection, greatly reduces emissions and is one of the reasons LS engines (and similar engines from other manufacturers) make more power than the old muscle cars. It is the reason American OHV V-8s overcame the 'smog era'. I know folks who have no cats, all AIR/EGR off their engine combinations, and through the use of good tuning still pass smog tests. (Although where I live in AZ, a Sherman tank is acceptable as we have no emission tests.)

Prost; Thanks

 

What your wife's CTS-V has is the same exact PCV system that is on the 2004+ LSx series engines in the Vette. I've mentioned it before, that the fixed orifice on the 2004+ LSx engines has a 2.5 mm (0.100 inch) orifice built into the metal tube nipple that comes off the right front corner of the valley cover. The fixed orifice PCV unit emulates the 2004+ design, as it's GM's fix for excessive oil consumption on some of their V8s. You may think that there is no PCV system on you wife's CTS-V, but it is exactly the same as someone putting the fixed orifice PCV unit in their early LSx engine's.

If you ran the PCV system without that fixed orifice, there would be way too much flow in the system and it would probably burn tons more oil than with the orifice in place.

Cars ran on the street need some kind of PCV system just to keep the innards of the engine clean. On a race car you can get away without a good PCV system because they typically get tore down on a regular basis, so sludge etc is no concern and because there are no emissions regulations. Some areas of the country do a visual inspection for emissions components, so going to a full race PCV system isn’t going to work well for some on the streets.

 

I'm at 1 qt every 1K miles.....


DH

 

It was $7 ..... but I don't know how to install it !!!!!!

The barbed end goes into a 3/8" hose. But the other end looks like its 1/2 to 5/8" ???????? Where does this go????????


DH

 

You know.....I never tried to look inside the tubing coming off my valley cover. If indeed there is the 2.5mm oriface built in I wonder if it can be seen. The tube itself is not the same large diameter as the fitting I bought with is pictured in the beginning of the thread.

If indeed there is such a small oriface, this may explain why I get so much oil out the fresh air line (path of least resistance). So I could place a small restrictor in the fresh air line to match them up. But this fat, at one end piece isin't going to fit in any hose I have.


DH

 

It's supposed to replace the original PCV valve ... which fits inside this special rubber "boot". You can see it in this photo. Since your Vette has the built-in orifice in the valley cover it never had an external PCV valve.

 

Ouch ... how much of that can you say is caught by the catch can(s)?

 

I should start measuring!!!!!!!.....but not very much... maybe an inch in AMW can?


DH

 

I take it your 1 qt/1000 mile use rate is due to track time? Or is it consuming that much with street driving too?

Every time I check and clean my catch can I pour the oil out and measure the volume and record it so I can subtract that from what is used. I assume the difference is getting burned up past the rings … or not all oil in the PCV system is caught by the catch can.

 

Thanks

I guess I need to get one of these boot which I assume is 3/8 at the end if I want to try this in the fresh air line.

Have you ever seen a picture or schematic that actually shows this restriction oriface inside the valley cover.

I'd rather have the old PCV valve and my catchcans.

I'm really starting to think that this restrictive oriface is forcing the oil upstairs into the fresh air line. I know some C6Z06 which have the same fresh air line to the airbridge puke up oil !!!!!!!


DH

 

This is a good discussion and has inspired me to install a coalescing filter and monitor oil consumption on my '01 Z06. I haven't noticed any real consumption yet, but I haven't looked in the intake manifold, either. The fixed orifice PCV valve seems like a logical install at this point, also. I may install a compound gauge on the PCV line at some point to monitor pressure in the system (at idle and when revved in neutral, parked with hood up). Interesting concepts at work here, and zero oil consumption would be ideal, so the closer we can get our engines to it, the better.

 

No, I have not seen any photo or schematic of the 2004+ orifice setup, but I do remember researching this and finding out somewhere that the 2004+ engines had the 2.5 mm orifice and no external PCV valve. I would imagine that the valley cover p/n is probably different for the 2004+ LSx engines if this is the case. Could call the dealer parts department and verify. It's possible if you looked down the tube coming off the valley cover with a flashlight that you might see the orifice.

It does make sense that if the PCV's dirty line is more restrictive than the fresh air line that more oil vapors would backflow to the throttle body at WOT.

If you read the tech articles I linked to in Post #37, it makes it sound like the fixed orifice PCV unit was supposed to also help keep the backflow out of the fresh air line ... the articles say that backflow was causing the sticky throttle syndrome. Here's the links again.

http://www.mightyautoparts.com/pdf/articles/tt122.pdf
http://www.mightyautoparts.com/pdf/articles/tt118.pdf

DH - can you explain exactly what kind of setup you have on your dirty and fresh air lines when you were getting so much oil in the catch can.

 

Remember that some of the oil that makes up the level you check with the dipstick is water and other "contaminants". This is why even though it seems that your car isn't using any oil, in actuality, some is being "consumed" out the exhaust. A coalescing filter will prevent some of the water, as well as oil aerosols from reentering your engine via the intake.

 

After thinking about all this, I'm now wondering if the location of the PCV valve (fixed orifice or spring loaded) in relation to the catch can has a bearing on how much oil is sucked in to the intake manifold.

Think about it ... if the catch can is between the intake manifold and the PCV unit, then the guts of the catch will see very high vacuum levels when the throttle is closed. This could mean that oil caught in the catch can could possibly be sucked out by the high vacuum levels ... especially if at high RPM and then the throttle gets chopped all the way closed. Also, if liquid oil did get sucked out of the catch can, that would essentially block the line for a short time, which could also cause excessive backflow down the fresh air line. This could be happening to guys on the track where the catch cans fill up some and they do a lot of high RPM throttle closing as they come in to tight corners, etc.

The 2004+ LSx engines with the built in orifice in the valley cover nipple would put the high vacuum on a catch can placed between the valley cover and intake manifold.

If the PCV unit is between the catch can and intake manifold, then the catch can sees a much less vacuum levels just like the crankcase. The 2001 to 2003 LS6 still has the external PCV valve, and therefore the catch can is placed between the engine and PCV valve, and doesn't get the high vacuum level at times of closed throttle. I'm wondering if that makes a difference on those setups?

The 2003 and older LS1s setups would put the catch can between the PCV valve and intake manifold, which means the catch can would have high vacuum levels at times of closed throttle.

So to summarize, the only catch can setup that naturally keeps possible high vacuum levels off the guts of the catch can would be the 2001 to 2003 LS6.

Humm … something else to ponder.