Delete head breather and pcv?

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  • S2mike
    S2Forum Hobbyist
    • Dec 2017
    • 20
    • Country: United Kingdom

    #46
    Originally posted by diesel des
    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.

    Sent from my Moto G (5) using Tapatalk
    Des could you draw a diagram of this setup just so I can understand this setup please

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    • betterwith4
      S2Forum Maniac
      • Dec 2014
      • 568
      • Country: United Kingdom

      #47
      Yes would be good as I hear you have to move the n80 sensor to underneath the intake manifold??? Would be good to see what pipes go were and how to set it up

      Comment

      • diesel des
        S2Forum Possessed
        • Feb 2004
        • 3896

        #48
        Very basic sketch. Basically block all existing head vents. Block intake manifold point. Modify sump to have a return/breather port at the side near the front as per pictures above. Should be 19mm min. Take a line from there and t into drain line from a proper seperator, a provent unit or a good cyclone style seperator. Not a box stuffed with steel wool or fresh air. That drain should be 12mm at the minimum, aim for 19mm.

        Continue out of that t (the hose from the sump drain that has its leg going off to the cyclone drain) into the original crank breather. That requires another t. Ideally upgrade the darliks head (what folk call the original block breather) to a aftermarket one as sold on this site. Again take a 19mm to 25mm line from there upto the intake of the seperator. The vent on the seperator can go to a suitable breather filter if you like the smell of oil in the morning, or back to your main engine intake filter for a sealed smell free mot friendly system.

        The idea is to keep the oil lines large in diameter so that the sump cannot build up pressure. Also this encourages the oil to seperate from the gas and return as quickly as possible to the sump where it's needed. Oil lines from the head can encourage oil to stay in the head as the flow of gas into the head trying to get out the head breather opposes the flow of oil to the sump. By blocking the head breather you have whatever leakage past the valve stems and seals pushing the oil back down into the sump on its way out to the sump or block breather.

        You want oil in the sump, not the head or breather system. If your tracking the car seriously consider an accusump. You need the 2 breather points, eg original block plus the new sump point so that if one gets blocked with oil for a few seconds the other continues to work. On launch normally the original block breather spits out some oil even with sump plates, so the new sump drain/breather point comes into action. During hard brakeing the front sump breather can get blocked, but the original breather is fine. Fitting large catch cans arnt the answer as you just end up with lots of oil in the catch can and not in your sump. Small drain lines are also useless as the oil needs to drain back faster than it gets into the catch can/seperator.

        Sent from my Moto G (5) using Tapatalk


        Comment

        • diesel des
          S2Forum Possessed
          • Feb 2004
          • 3896

          #49
          https://store.034motorsport.com/catc...-c4-s4-s6.html

          This is the 034 kit which isn't ideal for many reasons, but what is good is that cyclone seperator. As you can see the inlet feeds in tangentialy and the outlet dips down in to the body some distance. This causes the oil which is heavier than the gas to strike the outside walls and slow down, run down the outside and collect at the bottom. The gas is light and more nimble, so it turns a few times and goes vertically up and out the top where it can be vented to atmosphere or back to the intake filter.

          The supplied drain system is worse than rubbish. I drilled the bottom of the cyclone and fitted a 19mm return. I'm not suggesting you buy the 034 item, but get one made that works on the same principles.

          Sent from my Moto G (5) using Tapatalk

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          • diesel des
            S2Forum Possessed
            • Feb 2004
            • 3896

            #50
            Similar looking setup from land rover





            And from BMW




            Not saying these will fit, as port sizes may be wrong but the principal is correct

            Sent from my Moto G (5) using Tapatalk

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            • Thuppu
              S2Forum Freak
              • Sep 2010
              • 4115
              • Country: Finland

              #51
              I'm going to test those. Will use two in parallel At least one works very well on a 4.4l V8 N/A engine.

              Last edited by Thuppu; 29 August 2018, 17:23.

              Audi UrS4 Avant 2.5 20vt - twincharged - Project
              Audi 80q B4 Sedan 2.2 20vt - Daily user
              BMW 320d Touring e91 M-Sport - Daily user
              BMW 740iA e38 - Project

              Comment

              • diesel des
                S2Forum Possessed
                • Feb 2004
                • 3896

                #52
                Definitely worth a try

                Sent from my Moto G (5) using Tapatalk

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                • Tom_
                  S2Forum Extremist
                  • Oct 2007
                  • 1302
                  • Country: Czech Republic

                  #53
                  Folks, those provent tanks aren't available anymore, does someone have anything similar to prevent? like that Febi crankcase vent?Any reviews? Looking for some vent for my stroker
                  Audi Coupe Quattro 2.3 20V

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                  • K Simmonds
                    S2Forum Zealot
                    • Dec 2007
                    • 7633
                    • Country: Wales

                    #54
                    I made my own custom catch tank from an old air-con condenser can with a baffle plate inside, worked great, it's amazing how much crud it catches, no more oily residue in the intake system.

                    You could get one of the better catch cans from eBay and modify it to suit.

                    Though don't have a return to the sump as once you've seen what's in a catch can you defiantly don't want it back in the engine. I emptied mine about 1K miles, in the summer it would be less than a fifth full, in the winter it catches loads of water from condensation and would be over half full with a disgusting emulsion of oil and water in the same amount of time.

                    You could of course just vent to atmosphere to keep the just stop oil tossers happy.
                    1990 B3 2.0 80 quattro.
                    1992 C4 2.8 Avant quattro
                    1994 MTM RS2.
                    1998 B5 TDI quattro Sport.
                    2000 B5 TQS.

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                    • Tom_
                      S2Forum Extremist
                      • Oct 2007
                      • 1302
                      • Country: Czech Republic

                      #55
                      I have available some old air con as well, but not sure how much needs to be modified inside. I will be venting to the atmosphere just don't want to have those condensated fumes back in my engine.
                      Those stock units above looks good and arent pricey at all...Maybe using two of them will be good enough
                      Audi Coupe Quattro 2.3 20V

                      Comment

                      • K Simmonds
                        S2Forum Zealot
                        • Dec 2007
                        • 7633
                        • Country: Wales

                        #56
                        To use an air-con can it need's to be carefully cut open around the seam, to make it so the two half's will slide together, the pipe inside needs to be shortened and the original fittings have to be cut off and AN ones welded on.

                        Very hard to describe without photo's, I did have some on my old 3B project thread but unfortunately they're no longer visible.

                        I simply used what I had to hand as I have a mate that can weld alloy so it cost nothing apart from about £15 for three AN fittings and few hours of my time.

                        It would be much, much easier to use something ready made.

                        I actually retained the connection between the outlet and the intake boot as it can get a little smelly in town with a hot engine venting to atmosphere and I wanted to retain positive crankcase ventilation. A good catch can set up should stop at least 90% of the condensation fumes as they will cool and condense inside the can, but if you live in a country with very cold winters I'd go for an atmospheric vent as you plan to.

                        I tried it both way's for long periods and's there is no difference in performance whatsoever.
                        1990 B3 2.0 80 quattro.
                        1992 C4 2.8 Avant quattro
                        1994 MTM RS2.
                        1998 B5 TDI quattro Sport.
                        2000 B5 TQS.

                        Comment

                        • Tom_
                          S2Forum Extremist
                          • Oct 2007
                          • 1302
                          • Country: Czech Republic

                          #57
                          Thinking of buying the ProVent as this one looks solid and has a good reviews or that one from LandRover, but its a quite small. Winter here is similar to UK, but the car isn't winter car anymore. Only spring/summer/autumn
                          Last edited by Tom_; 3 January 2025, 10:53.
                          Audi Coupe Quattro 2.3 20V

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