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Weird User
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35 Posts
Discussion Starter · #1 · (Edited)
Hello,

I want to know if I need to plumb the Catch can back to the intake pipe.

My reason to ask is because I notice at idle it holds a vacuum. where is that air coming from? is it being taken from the intake pipes via the combustion process?? thereby using some air from the air flow meter?

NOW I have both cam covers going to the can, and the can's other pipe is vented with a little motorbike filter.
would this be confusing the AFM?

Is this a common style of pluming? or for smooth driving and best performance while using a Air Flow Meter should be it be plumed back to the Air Filter pipe..

thank-you
Shaun

Additional info.
Cam covers are bridged via the black middle hose (Rb25 by the way)
1 pipe to the catch can from cam covers.
the oneway valve on the intake side of the engine goes to the Intake plenum via a nipple thing. (Hose Joint)
Catch Can's 2nd hose is vented to atmosphere and a filter.

EDIT sorry, I know this been spoken about so many times before. but I have confusion as to where the one way valve should go if I was to plum back to intake pipe...
 

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tdi power
Joined
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13,297 Posts
some people say its right BUT

someone that used to work for nissan on the skylines did actually tell my mate while he was on a mapping course that they do need to be plus all the high power cars in japan and some here have a return to the afm pipe to suck the air back through after the vapour has settled and the oil collected at the bottom
 

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hippy
Joined
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7,682 Posts
at idle it draws vaccum from the one way valve thats between the inlet manifold and left hand cam cover,then under boost the one way valve seals and the vapours are drawn through the intake instead.
block up the takeoff on the inlet manifold for the one way valve when you fit the catchcan
 

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Weird User
Joined
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35 Posts
Discussion Starter · #4 · (Edited)
at idle it draws vaccum from the one way valve thats between the inlet manifold and left hand cam cover,then under boost the one way valve seals and the vapours are drawn through the intake instead.
block up the takeoff on the inlet manifold for the one way valve when you fit the catchcan
"The TAKEOFF" your referring to the actual one way valve (Black thingy) I should totally block it up?

thansk for the comments guys...

Ok, so I will do it like so,
both cam covers to 1 inlet of the CATCH CAN.
the outlet of catchcan to the intake pipe..
correct?
thanks

EDIT.. Added a photo of my engine.. as I donrt have stock intake plenum
 

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hippy
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7,682 Posts
the whole point of fitting a catch can is to stop oil vapours being drawn into the engine so no i wouldnt pipe it back into the intake
 

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Weird User
Joined
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35 Posts
Discussion Starter · #6 ·
I actually think the Catch Can is to protect against the event of a bad failure, and to minimize the vapor. as the internals usually have a steel wool type material which captures the oil and clearer air is outputted?!
 
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