Boosted One

iTrader: (6)

As some of you guys know I'm in the middle of a twin turbo build. I'm attempting to plan for incidentals so I figured I had better ask about catch cans. Do all FI cars need them, or just some?

What are your guys thoughts about running a couple vaccum lines from the valley cover to the suction side of each turbo?

Thanks for the input,
Frank

99Z28LS1

iTrader: (4)

I would like clarification on this as well, I started to think the catch can were only needed if the turbo was below the level of gravity and needed the oil to be pumped out vs having the turbo above the level and not needing a catch can

BlwnLs1GTO

iTrader: (12)

Whenever an engine is making more power, it creates more blowby. Or crankcase pressure. These are gasses that slip by the piston rings. Especially with FI and N20 applications. The purpose of a PCV (Positive crankcase ventilation) is to keep these harmful gasses from entering the atmosphere and by routing them back into the intake manifold. (Routing into the suction side of the turbo would serve the same purpose).

Some people eliminate the PCV all together and mount a filter only onto 1 or both valve covers to allow ventilation, rather than having the engine consume the gasses. As you may know, these gasses contain Oil vapors and in extreme cases can cause all kinds of issues when consumed by the engine. Detonation under WOT, loss of oil, Oil filled intercooler and intake pipes etc...
A catch can is a must if you decide to re-route PCV back into your engine. It's sole purpose is to remove and store the Oil vapors from Blowby before entering back into your intake tract.

Now I'll answer your question directly. Yes, you will need a catch can if you decide to keep your PCV system.

XtremeDime

iTrader: (16)

What are the options if we want to get rid of the PCV system altogether? Im told putting filters on the valve covers will allow unmetered air in and could cause issues. I was also considering putting a filter on the driver side cover and running an evacuation type setup on the passenger side valve cover to the exhaust so it will pull vacuum from there allowing the crankcase to draw air across the engine from the filter on the driver side, capping off all other ports of course. I want to know all options that exist without a catch can being present.

TransAmatt99

iTrader: (24)

My engine bad is so cramped I wouldnt know where to put one. I just have the little K&N's on the valve covers. They work fine.

siguy

same here one breather on the valve cover and i kept the stock pcv system on the driver side in tacked (i have an LT1) (procharger 12 pounds 383 motor)

Nasty N8

iTrader: (33)

We make a catchcan with a breather on it ideal for boost setups and for our valve covers. Keeps oil mess off the covers and vents the motor sufficiently. Working on a billet version too

Black_98Z

iTrader: (13)

The filters on the valve covers will not let unmetered air into the intake track. They just let pressure it and out of the crankcase. Now if you didn't plug the lines from the PCV that you removed now that would allow unmetered air in.

XtremeDime

iTrader: (16)

At the expense of sounding like an *******, this post did nothing to help anyone in this thread. I realize that you want to show your products but some of the sponsors on this site are ridiculous with doing nothing to actually help people, they just say "I have [insert product]" Were simply trying to find out what alternatives that we have to the stock PCV system. I can think of a dozen places to get a catch can setup but some of us are looking for actual input on what, why and how.

Tally TransAm

iTrader: (17)

you have to have some way to vent the additional crankcase pressure, whether it be breathers, catch can, pcv system whatever. otherwise you will have issues with oil drain back from the turbo as well as the high probability of blowing out a lot of seals and gaskets

i personally went with a vented catch can with a line running to each valve cover. clean, looks good, cheap. only have about 500 miles on the setup but working great so far

Boosted One

iTrader: (6)

Thank you everyone for the replys so far. This has been very helpful to me!

I do have a couple more questions though.

1- Is it ok to vent from the valley cover instead of the valve covers?

2- Would I be better off using a baffled catch can and pulling some vaccum from the turbo inlets?

Thanks,
Frank

Photochop

iTrader: (74)

On the 3 ls cars I've had that had aftermarket heads/cam and or turbo, I've used the open method. Run a metco or speed inc passengers side large breather on the stock fill location, a single mini filter/breather on the stock pcv nipple/port back of the drivers side valvecover and a single mini filter/breather on the ls6 valley cover front nipple/port (if applicable). Removed the rest of the pcv junk. Cheapest and easiest way - if you don't mind a lil oil smell in the cabin from time to time depending on how your hvac vents are configured. I've noticed no other side effects besides less using of oil between changes. Guess I've had pretty 'tight' motors because it hasn't ever been substantial enough to cause dirtying of the engine bay from misting out of the breathers.

Boosted One

iTrader: (6)

Great info! For as little as I drive the car oil smell will not bother me in the least. Do you get any oil stains/residue around where your filters are?

Photochop

iTrader: (74)

Yeah, a lot of other guys I know did the same and have pretty good success, just depends on how tight your motor is built - that will factor in with stains/residue. I don't notice anything with mine, but mine is no show car. If you've got lots of bling (shiny chrome/polished aluminum) under the hood then you may wanna think about doing something different because the smoke that comes out of the breathers may start to dull those finishes. But, if it does have the shiny stuff you'll more than likely be cleaning it more frequently anyway.

73 nova guy

iTrader: (8)

i was thinking of using a pcv in the one valve cover for light throttle applications then two -12 an's off the valve covers to an evac setup in the down pipe in boost? the low pressure in the down pipe would make a good suction for the breather system..

what do ya think of that ?

cjg454ss

iTrader: (27)

i ran a setup like that for the past two years, worked great, sometimes at the end of a pass it would pull oil out and burn it in the down pipe. got a lot of blue smoke and everyone thought the motor was blown everytime

Nasty N8

iTrader: (33)

Sorry trying to offer another option as getting the venting away from the covers and a catch can to collect any oil. Exactly like the post after with a picture of the vented can venting both covers is adequate.

You can vent from the valley but it usually does not have enough volume through the factory tube if you added a larger fitting there it could work.