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    Catch can setup

    I'm starting my S54 swap soon and have a couple questions about my catch can and vacuum setup.

    I'm gonna be RK-Tunes Alpha N tuned with 2M Autowerks velocity stacks so I'm planning to run a catch can with breather for the valve cover.

    On s54swap.com it says:

    ''Finally, the valve cover breather hose will need to be routed to the oil dipstick drain tube (must be added), or to a bung in the oil pan. The stock setup drains to a port on the rear sump of pan which is no longer present with the E34 oil pan.''

    Since I delete all my intake setup and adding a catch can. Should I still add a vacuum somewhere for the crankcase or I just bolt my M50 pan and that's it ?
    E30S54 - Scale Suspension / Unix Performance Coilovers - 17x8 and 17x9 BBS E50

    #2
    I can't specifically speak on the behalf of S54 swaps, but it's always better to have vacuum for the crankcase rather than not have it.

    You also don't have to drain the can to the pan or dipstick.
    Their wording is also very bad/lazy or possibly ignorant - a breather line from the valve cover straight to the dipstick or pan via bung will create crankcase pressure. How is it going to be relieved in this configuration?

    You can run a line from the valve cover to a can, then a line to one of the stacks as well. Maybe under it and hidden - the stack's succ will hopefully take care of any oil filming up your engine bay and create vac.

    1991 325iS turbo

    Comment


      #3
      That smells like the m54 way- the e46 drains the oil separator
      back to the dipstick.
      So if you run a separator, the m54 dipstick tube's an easy way to drain it.
      If your can doesn't accumulate oil, you don't need one.
      It always seemed a bit cheesy to me, the return system...

      t
      now, sometimes I just mess with people. It's more entertaining that way. george graves

      Comment


        #4
        The PCV system in the S54 is pretty advanced, it's basically 10 years in the making for BMW and the M5x line of engines.

        The wording on S54swap.com is wrong. The valve cover breather hose runs from the top of the valve cover to the intake manifold, from which vacuum is drawn. It's a black hose, looks to be plastic and is ribbed for some flexibility. You can't miss it.

        The stock setup drains to a port on the rear sump of the S54 oil pan. That is accurate, but it's a different line. It's a banjo fitting at the middle of the right edge of the valve cover, which runs down behind the exhaust manifold through a hard pipe which then transitions to a braided steel hose and into the oil pan via the port at the rear sump.

        I strongly encourage anyone on this subforum to check out the common approaches found on sites like e46fanatics.com, M3forum.net, bimmerforums.com etc.

        If you use an E34 oil pan and don't want to add a return port for the S54 drain line, you will want to put a catch can between a vacuum source and the valve cover in the area of the aforementioned black hose.

        An oil catch can is highly unnecessary for a naturally aspirated motor, because there's much less blow-by without turbo pressurization of the charge air. BMW put a pseudo-catch can on top of the valve cover and drained it into the oil pan, to me that's the right way to keep it. Put a bung on your E34 pan and plumb a vacuum source to the black hose on top of the motor and call it a day.

        Comment


          #5
          Originally posted by butters View Post
          Put a bung on your E34 pan and plumb a vacuum source to the black hose on top of the motor and call it a day.
          Ok, I put a bung in the pan to plug the head drain line and plug a vacuum on top of the valvecover. Now what should I do for the oil pan vacuum S54 have stock ?

          Blue arrow:

          Last edited by Jim Lepage; 04-17-2017, 12:36 PM.
          E30S54 - Scale Suspension / Unix Performance Coilovers - 17x8 and 17x9 BBS E50

          Comment


            #6
            Unfortunately, and confusingly, that's not the PCV drain port. The one for the valve cover drain is on the right side of the motor (passenger side in north America).

            Oil pan (crank case) vacuum is provided on the top of the motor. In the image below you'll see the hoses that someone used to run to a catch can like I mentioned before.



            Since you're running velocity stacks you'll need an alternative source of vacuum, I think there are options along the throttle bodies assembly. If I recall correctly, the larger metal tube above the throttles is called the "idle air plenum" and that might be enough vacuum for the crankcase if you can splice a connection into it. But that's wild hearsay so do some digging on what folks do for velocity stacks.

            Comment


              #7
              Thanks guys.

              I'm also gonna ask 2M Autowerks, as soon as my ECU made it to RK-Tunes.
              E30S54 - Scale Suspension / Unix Performance Coilovers - 17x8 and 17x9 BBS E50

              Comment


                #8
                Originally posted by butters View Post
                Unfortunately, and confusingly, that's not the PCV drain port. The one for the valve cover drain is on the right side of the motor (passenger side in north America).

                Oil pan (crank case) vacuum is provided on the top of the motor. In the image below you'll see the hoses that someone used to run to a catch can like I mentioned before.



                Since you're running velocity stacks you'll need an alternative source of vacuum, I think there are options along the throttle bodies assembly. If I recall correctly, the larger metal tube above the throttles is called the "idle air plenum" and that might be enough vacuum for the crankcase if you can splice a connection into it. But that's wild hearsay so do some digging on what folks do for velocity stacks.
                i doubt youd want to plumb into the idle system thats a lot of vacuum as it is post throttle. the normal place in the airbox is prethrottle which sees little vacuum if at all on the s54 especially with a carbon airbox as there is little to no pressure drop inside the box due to the enormous entry size offering no restriction except maybe WOT peak hp. if you dont have a box id be venting to atmosphere with filter somehwere near the wheel arch to keep fumes away
                Last edited by digger; 04-19-2017, 02:32 PM.
                89 E30 325is Lachs Silber - currently M20B31, M20B33 in the works, stroked to the hilt...

                new build thread http://www.r3vlimited.com/board/showthread.php?t=317505

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