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  1. #1
    Member Array
    Join Date
    Jan 2010
    Car:
    AccordCB7 Turbo

    PCV & Oil Catch Can

    So i've been having some dilemmas with my Catch-Can setup on my Boosted F22A.

    I started off with two Breather Hoses from the Valve Cover (one with a PCV ofcourse) going into the catch can.. And then venting to atmosphere.
    Never had any issues, but i really need to legalise it.

    So i ran another hose from the Catch Can into the Intake between the Air Box and Turbo.

    From all the searching i've done.. It seems that this should work.
    However it caused a bit of pressure buildup in the crank case and a small amount of blue smoke while idling aswell as driving.

    When you would remove the Oil Cap and block the Breather Hoses from the Valve Cover quite a lot of gas is expelled out the hole (Not uncommon for a Honda, and my Cylinder Leakage Tests confirm there is no issue)
    But when the Cap is replaced, and the Breather Hoses reconnected.. I instead remove the Catch Can Cap.
    And the amount of gas being expelled from the Catch Can is easily half as forceful as to what was coming directly from the Valve Cover.. Does this indicate a restriction problem?
    And another question.. With the setup described, does a PCV or Check Valve even need to be present? Surely because both hoses are now entering the Cold/Upressurised side of the Turbo i no longer need them.
    (Infact i could probably get away with blocking the PCV port off entirely, and running one line.. But i think i'll need two to prevent further restriction)

    I am now about to bore the holes in the Valve Cover large enough to fit a -10AN fitting.
    Which have about twice the internal diameter of the stock holes in the Valve Cover/PCV.
    And will run the same size hose (I think it's 5/8"?) as i was before.
    I will NOT run a PCV Valve, and will upgrade all fittings in the Catch Can and Intake Pipe to -10AN also.

    Can anyone see the new recircuated set up causing an issue?
    Any better ideas?
    From everything i can find on the Internet it 'SEEMS' that the -10AN fittings and hoses will be more than adequite but that makes me wonder why the stock lines are so tiny and there is no issues caused from them when your Motor is standard.
    But, i just want to confirm it before i wreck a Valve Cover.

    I have also read about a 'Bypass' system where the gasses are vented straight into the exhaust.
    But i have no idea whether or not this is legal and can not find any information from the RTA.

    Cheers!
    Last edited by Jccck; 25-10-2012 at 11:47 AM.
    It's not 4x4 status, think of it as "Winter Mode".

  2. #2
    Member Array
    Join Date
    Oct 2006
    Location
    Hunter Valley NSW
    Car:
    lownslowsedan
    Got a restriction problem for sure.

    on my SR20det it has a PVC with oil separator that goes back into the inlet manifold, and on the other side of the head a T that comes out of the block, one side goes back down to a recirculation box, and feeds back into the sump, and the other side goes to my catch can, which then has a hose back to the intake before the turbo.
    to see all of my build, checkout


  3. #3
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    Join Date
    Oct 2006
    Location
    Hunter Valley NSW
    Car:
    lownslowsedan
    I would do this.

    Dual breather lines direct from rocker cover to catch can, with no PCV, and then line from catch can to intake before turbo.

    You wont need a PCV valve because when youre on boost the negative pressure between the airfilter and turbo will suck air from the catch can/out of the rocker cover.
    to see all of my build, checkout


  4. #4
    Member Array
    Join Date
    Aug 2005
    Location
    Wollongong
    Car:
    Turbo 85 Civic
    Yeah, Trism is right, you dont need a PCV valve in you set up and the stock one will be causing a major restriction and there is no vacuum to open it.

    On my set up i have removed the PCV and put in a 1/2" barb and run a 3/8" line from the stock valve cover to the can.

    Keeping the black box on the rear of the engine as one of the lines is a good idea as it seperates alot of the oil out of the air before it gets u the catch can, unlike if you add a fitting into the valve cover.

  5. #5
    Member Array
    Join Date
    Jan 2010
    Car:
    AccordCB7 Turbo
    Quote Originally Posted by fat_85_civic View Post
    Yeah, Trism is right, you dont need a PCV valve in you set up and the stock one will be causing a major restriction and there is no vacuum to open it.

    On my set up i have removed the PCV and put in a 1/2" barb and run a 3/8" line from the stock valve cover to the can.

    Keeping the black box on the rear of the engine as one of the lines is a good idea as it seperates alot of the oil out of the air before it gets u the catch can, unlike if you add a fitting into the valve cover.
    There is no 'black box' on an F22A, or any of the larger Honda 4cyls to my knowledge.

    I have drilled the PCV and Valve Cover Breather ports out to 5/8" and welded a modified -10AN fitting in their place.
    Now the smallest part of the entire breather set up is 10mm (Previously/normal PCV is around 4mm)
    Can't see there being any problems now!

    PCV would work if still connected to the Intake Manifold via a seperate catch can, because vacuum at idle is still there.
    But there's no point in doing that, they now both run through the same catch can and then into the piping between the Airbox and the Turbo.

    Cheers guys!
    It's not 4x4 status, think of it as "Winter Mode".

  6. #6
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    Join Date
    Sep 2007
    Location
    Australia
    Car:
    your mum
    why do you wanna connect the catch can back to the turbo intake if it was fine before you do that?

  7. #7
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    Join Date
    Jan 2010
    Car:
    AccordCB7 Turbo
    Quote Originally Posted by connorling View Post
    why do you wanna connect the catch can back to the turbo intake if it was fine before you do that?
    ..Because it's legal that way.

    And if you'd seen my build thread/list of mods you'd understand that achieving a legal setup is very important to me =P
    It's not 4x4 status, think of it as "Winter Mode".

  8. #8
    Member Array
    Join Date
    Mar 2008
    Location
    under a bridge
    Car:
    Jdm EG6
    can u send a pic of how you have connected the catch can line to the intake? a couple instaces the angle that the pipe is in relations to the incomming flow of air through the airbox actually creates enough pressure to stuff the whose system up, usually if the catch can line is 80 degrees or less in relation of the incomming flow of air the system work alot more efficently and dosnt create a back pressure in the catch can system
    Quote Originally Posted by bennjamin View Post
    hmm id tap it. Even in mid air like that. Possibly with the pee pee flying out too.
    Quote Originally Posted by bennjamin View Post
    you guys remember squirtqueen.com ? I spent many a hr in computer studies in yr 10 looking that up.

  9. #9
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    Join Date
    Jan 2010
    Car:
    AccordCB7 Turbo
    Quote Originally Posted by rpm boy View Post
    can u send a pic of how you have connected the catch can line to the intake? a couple instaces the angle that the pipe is in relations to the incomming flow of air through the airbox actually creates enough pressure to stuff the whose system up, usually if the catch can line is 80 degrees or less in relation of the incomming flow of air the system work alot more efficently and dosnt create a back pressure in the catch can system
    Well the fitting is welded in on a slight lean towards the Airbox, so probably is around 80 degrees.
    Hmm, never thought there could be an issue caused by this.
    I'll see how it goes, it's not like it's hard to cut it out and weld another one in at a larger angle if need be.
    Cheers!
    It's not 4x4 status, think of it as "Winter Mode".

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