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Catch can setup for M20 - Valve cover vent

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    Catch can setup for M20 - Valve cover vent

    I can't find many threads that show catch can setups being run on an m20 (many are swapped cars).

    Please share your setup and how you vent your valve cover on your M20.

    #2
    I've got a turbo car, so I can't keep the stock setup. In the past I've run atmospheric vent, which is smelly and messy. Last setup was a catch can made of PVC pipe and caps, with some steel wool or something stuck in it, still atmospheric vent. Not sure how much it helped clean things up (probably didn't do much to get rid of the smell), but it did catch a little bit of oil, but not as much as expected.
    I've been redoing almost everything non-internal on the engine lately, and the next setup will be a cheap catch can from Amazon routed to the turbo compressor inlet, after the air filter. I won't pressurize the crankcase, and hopefully I can pull a slight vacuum to help move things along. Stuffed some copper scouring pads in it because it didn't have much baffling (though it was made nicely enough). Not sure how well it will work, but should get rid of the smelliness and dirtiness of atmospheric venting.
    3/4" hose fits nicely on the valve cover nipple.

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      #3
      3/4” heater hose to a the underside of the car. A “road draft tube.” But then again, my engine doesn’t have much blowby.

      IG @turbovarg
      '91 318is, M20 turbo
      [CoTM: 4-18]
      '94 525iT slicktop, 3L M50 + BW S366 project

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        #4
        I'm currently in process of experimenting with oil catch can set-ups in attempt to limit oil carry over issue into intake.
        I have stock M20 engine with BorgWarner EFR 7163 turbo.
        $26 "Ruien" Amazon catch can is mounted in pic below. After much deliberation this seemed to be the best spot for mounting.
        5/8" hose running from valve cover to catch can inlet. 5/8" hose running from catch can outlet to pre-turbo inlet.
        I currently still have oil carry over issues, but I believe that is more related to less-than-ideal turbo oil drain which I'm fixing now.
        Hope that helps!
        1989 325i Bronzit Coupe with manual conversion

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          #5
          Looks very similar to my setup on a turbo M20, I think I got the same catch can. No signs of oil entering the turbo inlet, haven't tried to dump the catch can yet. Car is MUCH less smelly than it used to be, but I also don't have a completely shot turbo now! (it used to jump pump oil past compressor seals into the intake).

          Comment


            #6
            I literally just routed the pcv circuit to the compressor inlet and called it a day. Blocked off the inlet on the throttle body. Drove the car for 20k miles like that. Intake tubes are a little oily and smelly, but I would say pretty average for a 36 year old car.

            I'm redoing the whole system now and am considering adding a catch can between the valve cover tube and compressor inlet.

            I wouldn't vent to atmosphere because I like keeping all the relevant emissions controls in place and routing to the compressor inlet was very easy.

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              #7
              I made a baffled can with a hose to the compressor inlet. Hose matches the size from the valve cover right through. 22mm (7/8'') if I remember right.

              It will make the engine more prone to det if it's pulling oil in.

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                #8
                Originally posted by 14thirty View Post
                I made a baffled can with a hose to the compressor inlet. Hose matches the size from the valve cover right through. 22mm (7/8'') if I remember right.

                It will make the engine more prone to det if it's pulling oil in.
                Engine bay looking good! I like how you plumbed it. Mine currently is super ugly just going over the valve cover, this looks more stock-ish, running alongside the radiator hose / along the charge pipe.

                I feel like I heard that before, about the oil/detonation issue... So, yep, I'll have to come up with a solution to aid oil separation. Looks like there's a lot of off the shelf options - why did you fab your own?

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                  #9
                  Thanks. I found a lot of off the shelf ones either don't have any baffles inside, and/or the ports are too small. Also I was limited by space.

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                    #10
                    Just get a long heater hose from Oreilly that fits the valve cover nipple.
                    grab your favorite can of beer 🍺 drink it. Open up the top with a knife put the hose half way in there zip tie it all together nice with 23 zip ties like MJ then open another beer sit down and just look at it
                    sigpic

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                      #11
                      https://www.ecstuning.com/b-mishimot...fiber/mmocccf/

                      88' Seta 2.7i

                      https://www.r3vlimited.com/board/for...430-my-88-seta

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                        #12
                        Don't spend $135 on that, search "carbon fiber catch can" on ebay and sort by lowest price. I bet the same thing is available for a lot cheaper since mishimoto is just chinabay stuff with a brand name attached.

                        IG @turbovarg
                        '91 318is, M20 turbo
                        [CoTM: 4-18]
                        '94 525iT slicktop, 3L M50 + BW S366 project

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                          #13
                          I also think that catch can, like most/all cheap catch cans, come with fittings that are way too small.
                          Originally posted by priapism
                          My girl don't know shit, but she bakes a mean cupcake.
                          Originally posted by shameson
                          Usually it's best not to know how much money you have into your e30

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                            #14
                            I am running two of the larger nuke catch cans - one for blowby and one for coolant. They are expensive and look fancy, and they do work well... but at the end of the day they are just a catch can, you can save a lot for the same functionality if you don't want the eye candy. The blowby one will eventually be plumbed, probably, to the exhaust post turbo but for now is back into my intake. Had it to atmosphere for a bit but people kept thinking my car was on fire when I was stopped at lights and whatnot. I located them just behind the headlights. These are the best pictures I have taken recently..


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