Is My Catch Can Set Up Right?

[ClutchBurndout-:(]

hey all, installed a catch can over the weekend, just want to make sure its right, because when i was driving home the other day my car seemed to nearly stall for a second and i thought that i have installed the can wrong. for the record i got a catch can with the air filter, so the engine can breath.

[ClutchBurndout-:(]

forgot to mention its an RB25DET

[ClutchBurndout-:(]

after some research last night i changed my setup, how does this look now?

[blind_elk]

after some research last night i changed my setup, how does this look now?

It's supposed to be a "closed" system. The first option is open to atmosphere, which contributes to the "almost stalling" you encountered.

The second option is the way I have installed mine. But unblock the PCV hose (between valley and plenum).

[ClutchBurndout-:(]

It's supposed to be a "closed" system. The first option is open to atmosphere, which contributes to the "almost stalling" you encountered.

The second option is the way I have installed mine. But unblock the PCV hose (between valley and plenum).

how come i need to unblock the hose? wouldnt this ruin the whole setup? as the fumes would still get into the intake?

[blind_elk]

The PCV valve in the plenum only opens under high vacuum, positive pressure jams it shut. The PCV valve is basically only open during "closed throttle", and the minimal amount of oil vapour that might be ingested isn't a problem for the engine.

The problem is when oil fumes are taken from the rocker covers and circulated back through the inlet side of the turbo. The oil (vapour) mixing with the fuel and air severely lowers the effective octane rating of the "fuel", which can cause the mixture to detonate. It won't detonate at effectively idle (throttle closed). The catch can is designed to condense the vapours so they don't reach the inlet side of the turbo.

[ClutchBurndout-:(]

The PCV valve in the plenum only opens under high vacuum, positive pressure jams it shut. The PCV valve is basically only open during "closed throttle", and the minimal amount of oil vapour that might be ingested isn't a problem for the engine.

The problem is when oil fumes are taken from the rocker covers and circulated back through the inlet side of the turbo. The oil (vapour) mixing with the fuel and air severely lowers the effective octane rating of the "fuel", which can cause the mixture to detonate. It won't detonate at effectively idle (throttle closed). The catch can is designed to condense the vapours so they don't reach the inlet side of the turbo.

so if i keep it blocked, whats the cons of that? cos id like to keep even the small amount of fumes out of there... or is there something very wrong with having it blocked?

ta

[pipster11]

nissan did lots of research and put the pvc valve there

as did lots of other manufacturers

2nd setup looks right, but unblock the pcv, it does things at idle and light throttle but sfa on boost when your getting the most blowby

get some steel wool and put it in your catch can (making sure that non is gonna come off and go into the turbo)

the fine wool will catch the fine oil droplets, thus making the catch can more effective

[ClutchBurndout-:(]

nissan did lots of research and put the pvc valve there

as did lots of other manufacturers

2nd setup looks right, but unblock the pcv, it does things at idle and light throttle but sfa on boost when your getting the most blowby

get some steel wool and put it in your catch can (making sure that non is gonna come off and go into the turbo)

the fine wool will catch the fine oil droplets, thus making the catch can more effective

ok cheers, will look into the steel wool, and unblock the pipe, im gonna have to get some new pipe though since theres no way i getting the ball out lol

[gotRICE?]

To me it looks like the 2nd pic that you have actually completely sealed off the cam covers from breathing at all.

Without the PCV or the breather to the intake pipe wouldnt the crank case pressure get rather high? As it has nowhere to go.

[blind_elk]

To me it looks like the 2nd pic that you have actually completely sealed off the cam covers from breathing at all.

Not at all. The piece marked "PVC line" is the pipe back down to the turbo intake.

Basically all that has happenbed that a can has been inserted between the LHS rocker cover and the turbo intake.

[gotRICE?]

Ahhhh i see! Makes sense now, it just looked like it had a block in it with that grey circle If the intake pipe was there, then i would have understood!

And i would have called it differently, as people generally relate "PCV" to the line between the intake cam cover and the IM that actually has the valve in it. The turbo breather hose just has a little brass restrictor

Makes complete sense now!

Im thinking of modding my setup due to other issues i encountered, like below. (3rd line closest to radiator is "MS Paint'ed" on.)

Deleted breather filter, and PCV as per factory.

Edited July 30, 2010 by gotRICE?

[08yannch]

i have heard about ppl putting a compressor water separator between the plenum and the rocker cover to filter out oil on that side and a catch can set up (like above) to filter out oil vapor on the other side. maybe something to look into ?

but the second set up look good just remove the ball bearing

[ClutchBurndout-:(]

why is everyone saying my setup is only venting the LHS valley cover? i have both valleys connected to one hose, then to the catch can, is this correct? both my valleys are going to the catch can correctly?