I have a C5 that is a dedicated track-car. It is set-up as follows:
LS6 with FAST intake and LS2 throttle body. It also has the 04 LS6 valley cover
Stock PCV system has been eliminated.
Valve covers are plumbed together to a single breather can.
Valley cover (04 Z06) is plumbed to it’s own breather can (smaller than valve cover can),

My issue started with the breather can for the valve covers filling-up with oil after 6-7 laps. After pulling intake to verify that is does have the 04 Z06 valley cover, I decided to block off both valve cover fittings. It then started pushing oil out from around dip stick tube.

I think I will plumb the valve covers back to breather can as it was originally set-up, but how do I keep the valve cover breather can from filling with oil on track?

 

Is there a vacuum source on either can? Or is blow-by the only thing forcing air/oil into the cans?

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NEVER block off everything. Every engine has blowby, which will pressurize the crankcase until it finds a way out via a gasket, seal, or even a dipstick. I had a catch can. STILL got oil in the intake. So, I went back in time and installed BREATHER HOSES!!! Works for me!! Worked for hundreds of millions of other engines throughout history, too. I have no oil under the car when parked, no oil in the intake, and no worries about it, either!! I'll probably get hammered for this , but the old saying "Nothing succeeds like success" comes to mind. Had the hoses on for years, maybe 15,000 miles. Again, works for me......

 

I assumed that having the 04 Z06 valley cover would handle the crankcase pressurization.

 

There is currently not a vacuum source to either can.

 

The LS6 valley cover system works off the vacuum/pressure of the intake manifold, it's not a free breather. I had similar issues for years, the more mods, richer tune, you'll get more blow-by and more oil accumulation. To start, try routing your vents out of one valve cover or the other depending on the direction of the track. More right turns, vent from the right, etc. Street drivers and drag racers wonder why we're having such issues, but they're not pulling 1.5Gs in corners all day. It's a very tricky thing to get it right for a track car, crankcase pressure will keep the oil from draining back to the block from the valve covers, then centrifuge pushes oil into the baffles and clogs the air line, and that oil goes into the can. When (and while) the can fills, your intake gets the overflow. I'm not complete yet but I added a GZ vacuum pump, a breather box and overflow tank. Breather box receives the blow-by gasses and some oil, the oil drains into a vertical holding tank to avoid contact with the breathers (the problem with breather cans, the oil goes everywhere when the can fills or oil sloshes around at high Gs). It can take a lot of oil without issue, and with a 3Q Accusump I'm not worried about starving the pickup in a 20-30 minute session. I had to add restrictive pushrods to reduce the amount of oil at the valve covers (I don't recommend this unless you have a HP Melling pump). Still have yet to complete a session due to other issues (fuel pressure), but I no longer have any oil in the intake, which means no smoke after decel.

If that all seems like too much, go check out Mighty Mouse cans - they're the best way to handle the oil problems in the traditional method.

 

 

I would second the Mighty Mouse catch can. You need to be drawing air out of the crankcase from the valley plate, and pulling fresh air into the valve covers. Are the covers factory with the baffles inside? If not, baffles will help control oil flow around the vents during cornering.

Here is my setup. The vacuum comes from the intake behind the throttle body to the side of the can. It pulls the air out of the valley plate from the fitting on the front of the can. The fresh air inlet to the valve cover comes off the side of the throttle body. The nice thing about the Mighty Mouse can is that is has a check valve under the filter so you can eliminate the PCV valve (per their instructions). If the system over pressurizes for some reason it will vent our the filter.

 

Kubs, I like the car! FWIW, I only started having oil control issues (smoking after deceleration, etc.) after I added long tubes, LS6 intake and a rich roadracing tune. With more air and fuel comes more blow-by. I look at that hose directly from the VC to the throttle body and I wince. I know guys that add a catch can on that connection and still get so much oil that it pools under the air filter. Think of what that's doing to the MAF. For modified engines, IMO you need two catch cans at least, one on dirty side, one on clean side.

 

I had similar issues, went to this setup.






2 -12 AN fittings welded into the valve covers and a -12 line venting each VC into the mighty mouse can

 

Looks like catch can will be the way to go at this point.

Thanks for all of the input.

 

Thanks!

I hear what you are saying, I had concerns also. The valve cover has a big baffle under the hose barb. That hose has stayed dry for me after about 5 event this year (just bought the car in December). I have a tune on the stock engine/exhaust and only got maybe a few ounces of oil in the can after all my events this year. My car also only has 35K miles. My buddies '02 Z has like 90K and smokes a bit on track, but he still doesnt get a lot of oil in his EE catch can.

 

I assumed the later valley cover would've worked, too. It may have helped, but oil still got by it AND a catch can......

 

@grinder11 - what I don't get is, if you had that much oil getting past the catch can from the valve covers, how do you not have oil spewing out a breather hose (if I understand your definition of a breather hose to mean a hose that ends in an element venting to atmosphere). Some of the messiest engines I've seen have been the result of oil filler cap breathers, catch can breathers, etc. that are just waiting to fill the engine compartment with oil spray. Every engine and driving style is different, just trying to learn.

 

Good question, for which I have no good answer. The only thing I can think of was the high vacuum was picking up more oil mist than it should have. Maybe the oil mist woulda stayed put and returned to the sump without a vacuum source. Maybe like sweeping the floor with a bagless vacuum cleaner that just isn't trapping all the dirt and dust, so it pukes some of it out where it shouldn't? I don't know. I do know the catch can would only get about 3/8" deep of oil in it, and then any oil mist would go right to the intake, sooooo.......

 

FWIW, I had issues with my catch can filling up in a single track day when I had manifold vacuum pulling on the catch can, and the catch can pulling from my (2002) valley cover.

At the suggestion of the Mighty Mouse guy (I forgot his name...) I put the stock PCV hose between the valley cover and manifold, and used pre-throttle body vacuum (very light vacuum) to pull on the catch can, with the can pulling from a valve cover, and had far less oil collecting in the catch can. No problem at all getting through a whole track day. The MM guy said the cam slings oil at the top of the valley, and the manifold vacuum is too strong, so they're a bad combination. The factory line has a restriction that makes them play nice together.

 

Right now I'm using the valley cover vent as a vacuum gauge port, so I'm not pulling at all from there. Funny that when I first put in the LS3, I got gobs of oil from the VCs but not much at all from the valley cover/catch-can/manifold plumbing. This all started because there was no port on the throttle body on the LS3 like there was in the LS1. I didn't know what to do with the VC vents so I just vented them to atmosphere through a catch can. Therein lies the start of the saga.

 

Happy to help with any specific questions!

 

Had similar issue/experience. Mine was valve covers, but same idea. Valve covers fill up with oil following a long high speed straight (lots of high rpm), then you go into really high manifold vacuum on braking, just sucks oil right out into the can. So I think a simple vented to atmosphere setup has some benefits for track day use. Then I can re-connect the vacuum source once again on the street.

Lots of good setups out there. I went way overboard and run a -10AN vent on each valve cover now.

 

In case anyone is watching this thread, I did a full track day yesterday with the GZ pump, pulling from one VC (I have it plumbed to both with ball valves to turn off the one that will see the most flooding based on the track direction), and it was a predictable - about a quart of oil in the can after every session. I have a setup with a gravity-fed secondary holding tank to get the oil away from the breather can and a drain with a solenoid valve on a switch that empties under the fender (no more unscrewing hot cans to empty). I tried vacuum on just the valley pan cover figuring it may ingest less, but got almost no vacuum registered on the gauge when reading the VC port. So, valley pan cover port works to gauge vacuum, but not for pulling vacuum. Maybe the PCV valve integrated in the cover is closing? With both VC ports open to vacuum I get max numbers, it stays up at 8-9 in (where the relief valve is set to purge) even under WOT. With one VC open, I get 5-6 in, and it comes down to 0 under WOT due to blow by. On high-rpm decel it comes back up to equalize the cylinder vacuum and prevent sucking oil past the rings. On midrange RPM decel it doesn't pull enough vacuum to equalize so I still get some oil burn, but that's a cool-down lap scenario. All in all I think it's manageable, and I don't think I'm getting any more oil than I was using a basic catch can that would fill up and explode out the breather after only a few laps.