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Delete head breather and pcv?

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  • #31
    Originally posted by Thuppu
    Drain back should be under the oil level so you have it right.
    It depends on what you want to do. The idea of the drain back at the front of the sump above oil level is so the drain actually becomes a vent under hard acceleration. It seems to work very well this way.

    Sent from my Moto G (5) using Tapatalk

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    • #32
      I was under the impression that during boost with oil pressure being 5bar the oil down there is everywhere so I'm not sure how much of a vent it may do.

      In my setup I still get the odd weep from the top rubber gasket

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      • #33
        You don't have 5 bar oil pressure in the sump. At least I hope not! It should be close to zero, only being at any pressure due to the restrictions in the breather system. So make the breather system pipework large in diameter and take as many points as possible from the crank case. Just don't take any from the head as it encourages oil to stay there and not return to the sump.

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        • #34
          Originally posted by diesel des
          You don't have 5 bar oil pressure in the sump. At least I hope not! It should be close to zero, only being at any pressure due to the restrictions in the breather system. So make the breather system pipework large in diameter and take as many points as possible from the crank case. Just don't take any from the head as it encourages oil to stay there and not return to the sump.

          Sent from my Moto G (5) using Tapatalk
          My thoughts exactly!
          Mine drains back in through the puck where the original breather exits. Which is above oil level and i contribute this as the reason no oil is in the catch can as it encourages it to drain straight back under no pressure.

          Having only 2 x Crank case breathing works very well for me and my setup.
          Current:
          1993 Audi S2 Kingfisher Blue - GTX3582r w/ E85 = 430kw atw

          Past:
          2002 Audi S4 Nogaro Blue Stage 3+ - 250kw+ atw
          2001 Audi S3 Silver - 169kw+ atw

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          • #35
            Sorry I didn't mean it that way, ie having 5 bar of pressure in the sump,
            I meant that during high rev/boost when oil pressure is at 5bar the oil being picked up in the sump as well as the moving parts within that area would be splashing the oil everywhere therefore I'm not sure how much sense it makes to have an oil return above the oil line, as there may not be an 'oil line' at these moments

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            • #36
              The setup I have is using the original pipework up to the point of the one way valve, only now crankcase breather and head breather goes to a swirl pot, which drains back to the sump, and the swirl pot is also connected to a secondary tank that eventually feeds back in front of the turbo.

              The internal tube on the top head cover is also converted to be a breather which heads to the pot.

              I added an additional hose from the head to the swirl pot recently which reduced problems of leakage from the rubber gasket.

              Essentially there are 2 exits to the swirl pot from the head and one to the bottom end(original).

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              • #37
                Have you done any track driving with this setup? Using head breathes only on track is how I managed to destroy a bottom end as all the oil got into the head and catch cans and not in the sump. Breathers from the head just encourage oil to places it's not needed. 90% plus of the gases that need vented come from the piston blow by so vent them where they originated, eg the crank case.

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                • #38
                  The original large crank case vent is operational and heading to the swirl pot via the OEM metal tubing. Isn't that large enough to suffice? I have deleted the plastic pcv valve due to the existence of the swirl pot.

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                  • #39
                    The original crank breather is ok, but could do with some assistance from a second breather on the crankcase. Once that is in place the head breathers can be blocked.

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                    • #40
                      So you suggest another hole on the block for that?

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                      • #41
                        Another hole in the block would be good but difficult to do, that's why we use the pipe in the sump as shown in the pictures. So to sum up the system I use is like this.

                        Modified block breather using the billet one available for this forum. The output of this is 19mm and it tees into the 19mm one from the sump. The 19mm one from the sump tees off at low level to connect to the drain from the seperator. The 2 breathers combined then changes to a single 25mm one feeding the provet 200 or 400 seperator I use. 400 on urq, 200 on urs4.

                        The provet 200 is on the small side and it's original paper seperator is a little restrictive so I have replaced it with a stainless steel mesh which is less efficient but flows better. The 400 is fine with the original paper seperator, but it's physically too big to fit in my urs4 easily. Fine in the urq. I tried another catch can cyclone seperator after the provet but only collected water so I removed it.

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                        • #42
                          Hello,

                          I could do this on the stroker, only I should be able to route the hose on the metal tube that goes into my swirl pot bypassing the one way valve. OR do you think better not to bypass the valve and just keep the use of the one way valve and increase the outflow of the crankcase?

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                          • #43
                            I don't use the 1 way valve setup so I can't comment on that. I can see its advantages though and might try that at some point.

                            Sent from my Moto G (5) using Tapatalk

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                            • #44
                              the main problem with the stock location sump breather is that on hard acceleration, all the oil moves to the rear of the sump exactly where the breather is.
                              Hence this forces oil up through the breather and check valve.
                              I was filling up my catch can, and making a mess of my engine bay after only 2 solid WOT.

                              I now deleted my head breather, ran the pipe like diesel des has, and have had zero oil problems.

                              i dont even run a check valve either.

                              Current:
                              1993 Audi S2 Kingfisher Blue - GTX3582r w/ E85 = 430kw atw

                              Past:
                              2002 Audi S4 Nogaro Blue Stage 3+ - 250kw+ atw
                              2001 Audi S3 Silver - 169kw+ atw

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                              • #45
                                Is there a definitive guide on this with diagrams to better explain WTF is happening ?
                                I would also like to see it compared with breather systems that incorporate a swirl pot.
                                Paul Nugent
                                Webmaster http://S2central.net
                                Administrator http://S2forum.com

                                1994 S2 Coupe ABY - aka Project Lazarus
                                2001 A6 allroad 2.5TDi - family tank
                                2003 S4 Avant 4.2 V8 - daily burble

                                Purveyor of HomeFries and Exclusive agent for Samco hose kits (S2/RS2)

                                There are only 10 kinds of people that understand binary - those that do, and those that don't

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