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JMortensen

Oil control mods for autox/road racing

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Had my Z out at an autox last weekend and after three high rpm runs my L33 5.3 started leaking oil out of the top of the engine, still not sure if it was valley cover or valve cover but it was all over the top of the engine. 

Question is for those of you who have road raced or autoxed: what mods have you done to get the oil out of the heads and back in the pan? What worked, what didn't, etc. 

Right now I have a baffled trapdoor pan and 3 qt Accusump and my PCV is just the hoses off the valve covers to a catch can with breather. I've been looking at drilling holes in the lifter trays, porting the oil return holes in the head, switching to later PCV (LS2 I think is the one with the baffle in the valley cover), seen return hoses added directly to the head and oil pan. 

Would like to solve the problem without pulling the motor if I can, but may not be possible.

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Well, still working it out. Now thinking I might not have the fresh air vent at all, and instead route the valve covers and valley cover to the can then to the intake.

EDIT--would have been one valve cover to the vented can, the other two PCV hoses T'd and attached to sealed catch can and to intake manifold.

Edited by JMortensen

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Theres a guy on youtube I saw a while back that says he road races his corvette. He had a nice setup, said it works well. All I can remember was he used this cap.

 http://www.eliteengineeringusa.com/clean-side-oil-separator/?fbclid=IwAR2WGZ9Lf5t0tKaDdAQg1YXPCqvKwETUDb7OfuIhG_4Or_PMXpM1ZetCEAk

If I can find the guys vidoes, I'll post it here. 

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The car has only been out twice since the V8 swap, and this course was much more favorable to the high hp rear drivers so there was a lot more high rpm/rev limiter stuff going on. But yes, this is the first time this has happened. Course was about even right to lefts, maybe a few more rights, but not a lot more. 

Edited by JMortensen
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My LS3 has three vent hoses from the factory outlets into a large well vented catch can, no PCV valve. I'm certain enough to believe that these engines accumulate oil in the heads, higher volume oil pumps only make this worse. Seeing that I don't have any problems this aspect has not been a priority but with the RB engines a oil scavenge pump under the valve cover and switched by the ECU worked well and made a significant difference to oil pressure data readings.

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Interesting. I did replace the oil pump when I installed the cam, but I just put a regular pump in it. The PCV setup on the LS3 includes a valley vent which I don't currently have, so maybe that just adding that vent will make the difference, don't know. I'm getting the parts in hopefully today or tomorrow. If I can get them delivered and installed I might hit the last autox of the season Sunday and that way I'll know if the problem is solved before the winter downtime. Other option was to do a dyno day, but that sucks funds away from my fiberglass project for the winter (wing).

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I autocrossed, hillclimbed and ran track days with a very well built SBC for years. Not an LS, but oil control problem is basically the same. I spent a lot of time re-designing the Valve cover and PCV system. Here's what I did.

 

1: Choice of valve cover is very important. Mainly in the baffling. The OEM Gen 1 and 2 had a good " Chimney " style baffle with angled baffle plates inside. These are much more effective at separating oil than many aftermarket styles . Some have no baffling at all, or just a flat plate positioned below the PCV hole. These ar next to useless.

 

2: I use the tallest valve covers I could find. GM Performance with the factory style " Chimney" baffle plates. The taller height of the Valve cover raise the Chimney, so if your get any pooling of oil in the head, it won't suck it up like a vacuum cleaner. 

 

3: Relocation of PCV valve. You should always run a PCV valve, but not from the Valve cover. I used a Chrysler style baffled Breather Cap where the PCV valve was originally located. These have additional baffling inside to act as an Oil separator. The cheaper ones are juts stuffed with steel wool. The better ones have both angled plates and steel wool. Both seen to be effective. 

 

4: I then made a Custom oil separator/ catch tank where the PCV valve was attached. I used a modified CSR aluminium Radiator overflow tank for this . The tank was about 3.5" in diameter by about 10" long. Here, bigger is better.  About halfway down ( a good 4 inches ) I welded a side nipple into the Can. The hose from the Chrysler breather cap attaches to this. I welded it at a tangent, so any incoming air/oil would spin in a Vortex. This helps separate the oil as it hits the side of the tank.

 

5: At the top of the tank I drilled a hole to fit the PCV grommet. The PCV valve was inserted at the top of the Tank and then went to the Carb PCV nipple ( Or manifold nipple on EFI ) . I did not install any extra baffling inside. The 4 " inlet below the OCV valve and the vortex spin was more than sufficient to separate any slight oil mist that got pat the GM " Chimney " baffles and the Chrysler Oil breather cap.  ( Extra baffling would certainly help in difficult cases though ) 

 

Worked extremely well for may years. Autocross is the most difficult test as you are constantly buzzing High RPM, then off the throttle ( High Vacuum ) , with braking and violent cornering maneuvers. This makes it very difficult for the upper end oil to drain off as it's being constantly thrown about and away from the drains. 

 

With this modification, The PCV system was still effective, but very little oil mist got into the Intake manifold.

 

You can see part of the CSR catch can ( Red bracket ) on the right side of the picture. Juts ahead of the W/Washer tank. PCV hose comes out of top and goes to Holley PCV nipple. You can just make out the Chrysler breather cap on the drivers side valve cover. Hose from breather cap ( 5?8" ) goes from Breather cap to side inlet of CSR catch can. Located well below PCV valve as noted. 

 

 

Air Box.JPG

Edited by Chickenman

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Another good option, is the Mann Pro-vent system. This is used on Corvettes and many European cars, including BMW.  They are a more sophisticated design of my homebuilt oil separator.   Stock GM PCV valve can go in line at outlet side. 

 

They work very well... but are kind of Butt ugly. The Pro-Vent 200 should suffice.

 

ProVent_en.pdf

 

418AP8QorxL.jpg51uvm-E40EL.jpg

Edited by Chickenman

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Well I changed out the valley cover for LS6 which has integrated baffled and restricted PCV. I plugged the valve covers and ran the valley cover PCV direct to the manifold. I have a catch can on order, but it didn't arrive in time for me to hit another autox. This one was wet and the car saw neither high rpms nor high g loads.

 

After the morning runs with Mark Haag as a co-driver, everything seemed fine but we pulled the hood, and there it was: oil all over. Brand new part torqued to spec and everything.

Borrowed a leak down tester from a friend. The motor still makes plenty of power, but thinking maybe blowby with load or something. Anyway will report back.

Fast car driving slowly: 

<iframe src="https://www.facebook.com/plugins/video.php?href=https%3A%2F%2Fwww.facebook.com%2FJon.E.Mortensen%2Fvideos%2F2059742714072074%2F&show_text=0&width=560" width="560" height="315" style="border:none;overflow:hidden" scrolling="no" frameborder="0" allowTransparency="true" allowFullScreen="true"></iframe>

 

Edited by JMortensen
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Some useful info there Chickenman, will look for alternative valve covers for the LS3 but exactly why should you always run a PCV valve on a competition engine? For one the air/fuel ratio is crucial, introducing pollutants to the mixture is crazy, it can only reduce performance or lead to engine damage with no advantage. The whole idea is to allow the engine to breathe and so relieve internal pressure, that pressure will always take the path of least resistance which should be to vent it into a remote can, by the time it gets there it's cooled down and the suspended 'oil' will precipicate (sp?) out and accumulate in the can. Last time mine was drained there was no oil as such, there was mixture of water and what looked to be a light weight fluid derived from petroleum, stuff that you would not want in your engine believe me. My engine runs as clean as, no doubt the Accusump set to open at 45 PSI has helped keep it in good nick, may this situation continue. 

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I'm probably just piling on info you already looked at but did you see these, (https://www.hotrod.com/articles/venting-to-cure-crankshaft-pressure/, https://www.yellowbullet.com/forum/showthread.php?t=609182&page=5)?  Is that how you plumbed things?  I saw a number of people claiming on road race LS motors you need half inch (-8 AN) or larger lines to deal with the problem. 

 

Before I did any of this I'd make sure you don't have excessive blowby/leakdown from a broken ring.  I should add that all this disappeared when we dry sumped Kipperman's engine.  His locost that had a wet sump LS2 had some vented breathers that ran to a catch can and it was always having some oil mist come out.  If you do want to think more about the dry sump I did my complete system using NASCAR take off parts for around $1300.  

 

Cary

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Did a leakdown test today, engine is fine. Hooray!

 

At first I just had the 3/8 lines from the valve covers to a vented catch can. Then I added the LS6 valley cover with the PCV. I haven't taken the stock valve covers off in years, so I don't remember if they are baffled or not, so in anticipation of this last autox I plugged them and ran the PCV from the valley cover to the intake and that was it. 

I bought a catch can but it showed up and only has 2 3/8" NPT ports, and I'm not convinced that I can vent all the pressure through a 3/8" hose. Thinking about returning the catch can and getting a different one and running -8 lines to it instead. Only problem is how do I get -8 to the valve cover and valley cover. Suppose I could drill and tap like I did the intake, but it's just another PITA.

After looking at it I'm also not inclined to do a vented catch can. Think a sealed can to some source of vacuum is the best answer, whether that be intake or a vacuum pump or something else... 

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A catch can with vacuum is obviously best, a vented catch can with adequate hose sizes is next best though. A properly set up catch can is really just an old school extension of how engines used to be before the anti pollution requirements complicated things and introduced considerations irrelevant for a race engine where polly lutions gives no f***k. Mine has same diameter hoses from all three available vents going to a distributor block from which runs I'd guess a -12 size hose (it's all out in the shed and I'm too comfortable to move) to the large vented catch can. It all works perfectly in a world where not everything does.

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I had so much oil in the catch can that it made me think part of the problem was just pumping too much oil up to the heads, so I bought a set of oil restricted pushrods with .040" orifices. Also picked up some valve covers with -10AN fittings off of ebay. Looked at my old catch can and it actually has 1/2 NPT fittings on it, so I'm going to buy some -10AN pushlok fittings and try straight venting again. If that doesn't work then I'll convert the can to vacuum and run a fitting back to the intake. Not sure what to do with the 3/8" line off of the valley cover. I've been told that I can run it to the intake but that basically creates a vacuum leak. Could T it into the -10 line and vent it, but it's a restricted orifice (not that easy to blow air through it) so not sure that it is worth it. Thinking T it into the vents and if I still have problems then I'll maybe remove it, drill a hole in the old valley cover and put a -10 fitting in there too.

Most people seem to think that the bigger vents should cover it, I'm hoping that is correct. Will have to install parts and wait for spring (or dyno tuning) to find out if it worked.

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The only fluid that ended up in my catch can was a mix of something like water and a smelly light fluid mix, just a bit though over a period of time. So properly and adequately plumbed they do work. But you have got me thinking about vacuuming the sump now, using a electric pump. Wonder if that would reduce oil aeration in the crank case which I understand is a problem but first thought is it would have to pick up from the sump and not the heads. As really any ideal vent system should.

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In my searching I've found 2 common vacuum pump setups. One is hardcore drag racer stuff where they use a big, powerful mechanical pump driven off the crank to put some serious vacuum to the crankcase. Runs about $1000. The other is to use a vacuum pump from one of the newer turbo cars that need it for power brakes. Newer Ford pumps seem to be the popular option, but they don't pull anywhere near as much vacuum.

 

I still like the old drag racing exhaust systems as there is no pump at all, but they're not legal in basically any road racing organization in the US. 

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