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Catch Cans - Again

maccattack

By maccattack,
in Engines & Forced Induction

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Bliksem Veteran

Bliksem

Posted
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To run an atmo can, you need to block the PCV valve and block the return to the intake pipe. You can then run both breathers from the cam covers to a vented catch can.

Yup thats that ive done. Filter is on the catch can which is in the airbox ....all hidden and contains any oil vapour.

bubba Grand Master

bubba

Posted
Posted
Yup thats that ive done. Filter is on the catch can which is in the airbox ....all hidden and contains any oil vapour.

Yeah it's the same as I run mine too. Wouldn't having the catchcan filter in the airbox almost defeat the purpose of removing oil/vapour from the intake stream?

Bliksem Veteran

Bliksem

Posted
Posted

Yeah, what I have is a pod in a cold air box and the filter on a length of hose directed away from the pod. When I get a chance i'll probably run the hose back out of the air box and out of the engine bay. Just waiting for some weld on AN fittings and it will all be done in braided line.

Neejay Explorer

Neejay

Posted
Posted
woops sorry i forgot to post the pic

this is the filter i was talking about

post-a43193-Catch-20can-20assembly.jpg

That works...but depending on how much blow-by you get, seems like you'd have to change it quite a bit right?

Yeah it's the same as I run mine too. Wouldn't having the catchcan filter in the airbox almost defeat the purpose of removing oil/vapour from the intake stream?
Yeah, what I have is a pod in a cold air box and the filter on a length of hose directed away from the pod. When I get a chance i'll probably run the hose back out of the air box and out of the engine bay. Just waiting for some weld on AN fittings and it will all be done in braided line.

Be careful with that filter on the end. I've read where numerous people have reported that the oil vapors will eventually clog inside the tiny filter and cause a blockage. Why not just run the atmosphere hose down below the chassis without the filter?

Neejay Explorer

Neejay

Posted
Posted
Can someone please tell me what hose they use to connect the catch can? And where you can get it.

Catch cans typically come with one hose already (at least from the 2 I've bought). I took it to a store that sells everything for houses and went to the plumbing section, and matched the hose that came with the catch can.

I would probably go to an auto parts store and buy some stronger rubber hoses though, as heat can make the original hose flex and possibly melt (these hoses are plastic; the clear ones with fiber threading)

bubba Grand Master

bubba

Posted
Posted
Be careful with that filter on the end. I've read where numerous people have reported that the oil vapors will eventually clog inside the tiny filter and cause a blockage. Why not just run the atmosphere hose down below the chassis without the filter?

That's how I run mine, it's tucked out of the way and you can't really tell it's atmo unless you noticed the blocked PCV valve.

MoogLe Community Regular

MoogLe

Posted
Posted (edited)

well since you wont be using the lines as actual OIL lines i dont think you need real high quality stuff for it

i wouldnt spend that much money on the hoses personally....

and about the filter i posted uptop, the clear bottom part can be unscrewed and emptied out.

Can someone please just confirm that running the catch can atmospherically that it wont be causing any vacuum leaks and explain to me why blocking the PCV is necessary to run it atmospherically? wouldn't my idea achieve the same thing? maybe if someone explained to me what the purpose of the PCV is in the first place i could understand....

Edited by MoogLe
Smity42 Grand Master

Smity42

Posted
Posted

Hi Guys,

I want to run a "100% plum back" setup for my new RB25, but the most fittings I can seem to find on a catch can is 3 (seems to always be 1 down low and 2 up high). Would the following set up work?

RB25%20catch%20can.jpg

Basically block the hole where the PCV valve goes into the cam cover, then both cam covers run to the catch can by a single hose (regardless of under boost or not).

Then one outlet runs back to the plenum (with the PCV Valve put in line) for when the engine is not under boost, and one outlet back to the intake pipe for when it is under boost.

I dont see the point in running an extra line from the hole where the PCV value goes into the cover to the catch can, as the air can get back to the catch can via the other line anyway...

Cheers,

Martin

bubba Grand Master

bubba

Posted
Posted

I would just put the catchcan inline with the return from exhaust cam cover. Don't screw with the rest (bad breathing can create lots of headaches) and all you really want to do is remove oil/vapour from the intake stream.

Essentially you want an "oil/air separator" not a "catch can". This means making sure your can is baffled and stuffed with something like stainless steel wool that's not going to disintegrate and end up in the motor.

If it's not being plumbed back, I wouldn't bother with the baffling or wool.

Neejay Explorer

Neejay

Posted
Posted (edited)
Can someone please just confirm that running the catch can atmospherically that it wont be causing any vacuum leaks and explain to me why blocking the PCV is necessary to run it atmospherically? wouldn't my idea achieve the same thing? maybe if someone explained to me what the purpose of the PCV is in the first place i could understand....

You'd have to get an inline PCV valve and put it in between that filter device and the intake manifold...otherwise the glass filter thing will see boost and burst. So it'd be [intake manifold -> inline pcv valve -> glass filter -> valve cover where old pcv valve was]

You can do either or, or do both. The glass filter deal would filter out gunk going into the intake manfiold, and having a catch can in between the valve cover and intake pipe would filter out gunk from getting into the intake piping.

I'm not going to mess with the PCV valve side for now...I replaced my PCV valve with a new one. Old one was clogged, causing smoke. I'm just going to set one up like I described a few posts back (both valve covers -> T fitting right before catch can nipple 1 -> catch can nipple 2 -> intake piping

Hi Guys,

I want to run a "100% plum back" setup for my new RB25, but the most fittings I can seem to find on a catch can is 3 (seems to always be 1 down low and 2 up high). Would the following set up work?

RB25%20catch%20can.jpg

Basically block the hole where the PCV valve goes into the cam cover, then both cam covers run to the catch can by a single hose (regardless of under boost or not).

Then one outlet runs back to the plenum (with the PCV Valve put in line) for when the engine is not under boost, and one outlet back to the intake pipe for when it is under boost.

I dont see the point in running an extra line from the hole where the PCV value goes into the cover to the catch can, as the air can get back to the catch can via the other line anyway...

Cheers,

Martin

With the ports like that, it will clog. When it catches the oil, it will block the lower ports.

Edited by Neejay

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