Is a PCV Oil Catch can necessary on LS engines?

[GeoffP]

I have noticed several people have installed catch cans in the PCV circuit on their LS engine. How necessary are these? I understand the purpose but don't want or need the expense if it's going to save me a bottle of oil every oil change. $80-100 is steep compared to a $6-7 qt bottle of Mobile 1. It takes a LOT of oil to pay for that expense.

[Chris02rex]

Its more for keeping the oil out of your intake. I believe they are more necessary on a turbo vehicle rather than on a na car. I may be wrong though haha.

[LS1-IROC]

Are they absolutely necessary...no..are they a good idea, you bet. If you have ever looked inside a LS intake that's been run without one, you'd wish you would have spent the money on one.

[GeoffP]

Thanks for the info guys!

[Rod]

Are they absolutely necessary...no..are they a good idea, you bet. If you have ever looked inside a LS intake that's been run without one, you'd wish you would have spent the money on one.

he is correct the LS intake fills with oil about an 1/16 to an 1/8 of a quart about every 3-4 weeks, most of it passes into the engine and is burned during combustion, injected or carbureted its about the same, the Gen 1 SBC does the same thing

[dontlifttoshift]

I really expected there to be more action on this thread.

Is the factory PCV system so aggressive that literally sucks the oil out of the valve covers and into the intake? Even with factory baffled covers? I ran lines from both covers to fresh air in the intake tube, does that help at all?

[GeoffP]

Rodney - I'm afraid I'm going to have to disagree with your statement about Gen 1 small blocks doing the same thing. I have had many of them over the years and never had one suck oil into the intake. Of course this statement comes with the caveat that they were in good running condition. Both SBC's I had that were in bad running condition burned so much oil that it was hard to tell where it was coming from and where it was going! The only other SBC I've owned that used oil was a new engine that used oil until it was broken in good (which is what I consider normal). It's the engine that's in my truck right now and doesn't use a drop of oil now that it has about 14,000 mi on it (new GM engine).

Having said all that I am curious why the Gen III's and Gen IV's are pulling oil into the intake so much that a catch can is recommended. I agree that they do use oil because my wife's Tahoe has always lost about a quart between oil changes and my co-worker's new 2010 truck uses anywhere from a quart to 3 quarts between oil changes. He suspects the PCV system so this thread, IMHO, confirms that suspicion. Apparently GM is aware there's a problem because a friend of his had a similar truck with a similar problem. GM replaced a "circulation valve" that stopped the excessive oil consumption completely.

However, I'm surprised there hasn't been more stink about this publicly because it's obviously a design problem that needs to be fixed (without a catch can). I may have to see if I can find out what the revised valve is so I can use one on my engine build - I hate the thought of a catch can in line with the PCV system. Plus, most of the ones I've seen a just plain ugly (and expensive).

[SparkyRnD]

sometimes they can look not so bad:

[Rod]

your right Geoff, lot of SBC motors hardly use a drop after break-in, I do know that the race engines we build(drag engines), some burn serious oil, but we change oil and plugs after only a few runs, my old daily driver/race motor was a 383 with .80 pistons and the bearing tolerances were very loose (clattered a little on start up) and it burned about a quart between oil changes, the plugs were at the edge of foul at every 3000 mile oil/plug change and after the first season of racing we built an oil-air separator with the help of a larger manufacture and the plugs could have ran double the life without foul, its not really a design flaw LS engine burn mostly on decel and works as a top end cylinder lubricant and adds longevity to the motors, (so I have been told)

[69cutlassrkt]

Are there any cons to deleting the pcv and running a breather?

[Rod]

Are there any cons to deleting the pcv and running a breather?

not really, there could be some blow-by through the breather from block pressure, could get the valve covers/ engine compartment a little dirty

[GeoffP]

Sparky - is that a can that you make?

[BuzzKillian]

Would sombody post some pictures of their tank installed.... this is first I have heard of this.

[martZ]

http://www.mikenorrismotorsports.com...atch_Cans.html

Lots of pictures. Sponsor of this site.

[BuddyP]

I've been kinda oblivious to the whole PCV setup until now, which sucks because basically my valve covers are pretty much worthless and now I have to spend a whole lot more $$ on a PCV system and fittings/valve covers.

What I really want to know is:
1. Can I just pull off one valve cover?
2. Does a tube need to be run between the throttle body and valve cover?
3. How would I plumb in the catch can? (Keep in mind I have a truck block so my valley cover has no PCV provision)

[parsonsj]

Are there any cons to deleting the pcv and running a breather?

Yes. The PCV system pulls dirty acidic vapor from the crankcase and burns it, while pulling fresh clean air to replace it. PCV systems are the main reason modern engines last so much longer than our old original engines. There's no good reason not to run one -- it doesn't cost any power, it reduces pressure on your gaskets and seals, and it improves your engine's lifespan.

[parsonsj]

Here's a good discussion of PCV:

http://forum.diyefi.org/viewtopic.php?f=24&t=357

[scherp69]

I've been kinda oblivious to the whole PCV setup until now, which sucks because basically my valve covers are pretty much worthless and now I have to spend a whole lot more $$ on a PCV system and fittings/valve covers.

What I really want to know is:
1. Can I just pull off one valve cover?
2. Does a tube need to be run between the throttle body and valve cover?
3. How would I plumb in the catch can? (Keep in mind I have a truck block so my valley cover has no PCV provision)

Buddy..I ended up buying a catch can from Mike Norris Motorsports http://www.mikenorrismotorsports.com...atch_Cans.html Mike's been very helpful in helping me answer how I'm going to run mine. Since my valley cover didn't have a PCV tube on it, I picked up one from ebay for $15.95 plus shipping. I'm going to run one tube to that tube and the other will go to the outlet on the intake just behind the throttle body. Hope that helps.

[SparkyRnD]

Sparky - is that a can that you make?

Yes, we make them for $90 for PT members ($100 retail). That is an overflow catch can, but we can build them for oil, water, et cetera, and can put whatever fittings someone wants (a slight up-charge depending on the fittings)

[BuddyP]

Buddy..I ended up buying a catch can from Mike Norris Motorsports http://www.mikenorrismotorsports.com...atch_Cans.html Mike's been very helpful in helping me answer how I'm going to run mine. Since my valley cover didn't have a PCV tube on it, I picked up one from ebay for $15.95 plus shipping. I'm going to run one tube to that tube and the other will go to the outlet on the intake just behind the throttle body. Hope that helps.

LS3 or LS6 cover? The LS3 cover doesn't have knock sensors. Don't know if I need them or not but my harness is hooked up ot them.