Catch Cans with Breathers

[G.T]

i've seen this topic beaten to death, with mixed responses on whether catch cans with breathers would work (without vacuum effectively "sucking" the oil/vapors out of the crank case) but i think i'd like to give it a shot after every oil separator solution eventually did let some oil (no matter how little) by.

i'm thinking, how about one catch can plumbed up to both the driver and passenger PCVs at once, with a breather?

something like this

 

[dysan]

This is the one I have and I have both sides plumbed to it.

http://www.jegs.com/i/JEGS+Performance+Products/555/52202/10002/-1

 

[Barricade]

Without vacume how could it work?

 

[dysan]

It's just there to allow crank case pressure out. I have taken out my PCV valve from inside my valve cover so whenever I'm in boost any excess pressure can vent into the catch can unrestricted.

During the cold weather is when you can see the oil/water mix in the can but right now I don't get much at all in it which is good.

 

[1 Alibi 2]

Had an air/oil seperator on the pvc side till I did my blower upgrade.
The shop doing the work, JDM Engineering, Freehold N.J., told me the blower needs the lube because of the lobe clearances. In the long run, not having the lube will hurt the blower..

 

[dysan]

Had an air/oil seperator on the pvc side till I did my blower upgrade.
The shop doing the work, JDM Engineering, Freehold N.J., told me the blower needs the lube because of the lobe clearances. In the long run, not having the lube will hurt the blower..

A bit odd since this is something JDM posted on here about them...

Originally Posted by JDM's owner
There is no right or wrong with oil seperators. We just choose not to use them because to make it work properly you have to have a sealed system. What I mean by sealed system is no breather caps or any other evacuation device hooked to the engine. Some of the oil buildup in the supercharged cars is from reversion on decel. These motors are extremely tight and on hard decel you can pull 30 inches of vaccuum, which will allow oil to be sucked back through the guides. With a sealed system that will still occur. With an oil breather cap, that will not occur. If a car is running enough power, say 500whp+, we will stick a breather cap on it. This helps two things. 1 is to control the oil being sucked through the guides on a hard decel and 2 pressure or boost that seeps past the rings will get blown out the breather cap. Once oil goes past the guides, it actually goes back up through the intake tract and gets sucked up into the supercharger. On a sealed system, under hard accel, as soon as you shut the throttle body, the motor is going to do everything it can to pull air from somewhere. The path of least resistance is the crankcase - it will pull it past the rings, from the PCV system, and even from the rear main seal - with the breather cap, you're giving it a path of least resistance. It is useless to use an oil breather cap and an oil seperator device because the oil seperator device only works properly on a sealed system. We just chose to use a breather cap so that when the motor needs to pull air, it does it from the atmosphere instead.

We have run tests here on the dyno that shows an oil breather cap cuts nearly 80% of the oil ingestion on a high horsepower supercharged vehicle.

Hope this helps,
Jim @ JDM

 

[G.T]

so i'm back to square one here..
i always assumed i needed some vacuum for the PCV to work, but i even checked with a few reputable tuners and was told it's alright to cap the PCV inlets on the manifold/intake, and just put a breather catch can!

as for the oil lubricating the blower lobes, i don't mind keeping the driver side PCV for that purpose..
it's the passenger side PCV gunking up my throttlebody that i wanna get rid of.

that said, i think i'll scratch the plan.. and attach both the driver and passenger side PCVs to a large separator that plumbs into the port on the intake manifold (behind the throttlebody)

that way, both PCV ports still have vacuum, and both will feed into the intake manifold without affecting the throttle body.. and whatever blow-by gets past the separator would lube up the blower (if that's necessary at all)

 

[SteveP]

A basic one with a filter from anywhere will work fine. The one you posted a pic with is for a pro mod type car. lol

 

[G.T]

The one you posted a pic with is for a pro mod type car. lol

does it matter?
i see it as two lines going into a canister with breathers on top! seems to fit the requirement!

eitherway, as i said above, i think i'll plumb both lines from the driver and passenger side into one (large enough) air/oil separator, and connect that to the intake manifold port behind the throttle-body

 

[1 Alibi 2]

A bit odd since this is something JDM posted on here about them...

.
Don't know when Jim posted to the other thread, only can relay what he told me on 04/29/2011..

 

[19COBRA93]

On a high hp engine, any oil getting into the intake and subsequently burned in the cylinder is a bad thing. It lowers octane and "can" lead to piston failure. I really question JDM's theory on "needing" oil to lube the supercharger (because they don't need it), and equally question their theory on oil being pulled from the valve guides and getting back up into the intake, and again question their theory that a separator isn't needed with a breather cap. I understand that they're saying about needing to pull air on decel (not quite to the degree of pulling crankcase vacuum like described), but it's the 6000 rpm wide open throttle full boost situation when the motor is pushing out a great deal of crank case pressure which is nearly saturated with oil particles, and those need to be separated from the outgoing air before it vents out of the breather.

 

[G.T]

now that i think about it, i too think that the supercharger has oil where it needs it.. the lobes shouldn't need any lubrication.

my main concern wasn't oil blow-by burning up inside the cylinder, as much as gunking up the TB and the intercooler core

 

[jodadejss06gt]

my main concern wasn't oil blow-by burning up inside the cylinder, as much as gunking up the TB and the intercooler core

You aren't concerned with reducing your octane number being supercharged?????


I've done this over and over. I had a steeda separator on my car na and it did its job, went turbo and got rid of it.

Started getting stuff into my turbo with no separator so I got a JLT separator. I was collecting nasty stuff in that at the end of winter(only plumbed to the driver side), but the passenger side had a little bit going to the turbo. I didn't like that happening so now I have both lines t'd together going into the separator and then to the inlet to the air filter elbow. I haven't gotten anything in the catch can in a while and have been to the track 2 times plus have been dd'ing the car. I don't know why I wouldn't see anything in it now???

I have K&N filters coming in today and am not sure if I should sell the jlt or just plumb the passenger side to the can and k&n on the other side of the catch can.

 

[69Mach1-409]

Edited: I need more coffee..




I capped both intake ports, run two K&N breathers on the cam covers, and have the CFM oil cap breather. No oily residue and that's with almost 1k miles and five 1/4 runs.

 

[Fallenauthority]

It won't let in unmetered air if the catch can is a sealed unit and not vented.

 

[69Mach1-409]

Sorry, I miss read it.. I'll edit the previous post.

 

[19COBRA93]

That will let in unmetered air.. (Air will be pulled from the breather, through the separator, and into your intake after the MAF) You'll have to get your tune adjusted for it from what I'm told.

I capped both intake ports, run two K&N breathers on the cam covers, and have the CFM oil cap breather. No oily residue and that's with almost 1k miles and five 1/4 runs.

The only time it has the potential to pull unmetered air would be under a hard decel. Otherwise it will always be venting air outward.

If you're getting zero oil residue on your breathers you've got a nice tight motor and/or they're not venting properly. I get a fair amount of blowby (what I would consider normal), and breathers right on my valve covers wouldn't work because I get oil dripping from from them from time to time.

 

[LBSRACING]

Edited: I need more coffee..




I capped both intake ports, run two K&N breathers on the cam covers, and have the CFM oil cap breather. No oily residue and that's with almost 1k miles and five 1/4 runs.

This is the method I am thinking of going with on my new engine. For me its more of I dont want all the hoses.

 

[jodadejss06gt]

The only time it has the potential to pull unmetered air would be under a hard decel. Otherwise it will always be venting air outward.

How would a sealed catch can allow any unmetered air in? The original message quoted by Mach was when G.T. said both pcv valve into can into intake behind throttle body.

Edit: I've heard that people with the oil fill breather + pcv valve breather get far less oil than just the single pass side breather.

 

[retfr8flyr]

does it matter?
i see it as two lines going into a canister with breathers on top! seems to fit the requirement!

eitherway, as i said above, i think i'll plumb both lines from the driver and passenger side into one (large enough) air/oil separator, and connect that to the intake manifold port behind the throttle-body

If you want to do that you have to run a closed catch can style. You can't run an open breather style with a vacuum source, as stated you would be adding unmetered air into the engine.


Earl