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Anyone know the flow rate of M20 oil pump?

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    Anyone know the flow rate of M20 oil pump?

    gpm or gph. Not finding any BMW inline 6 data points online.

    Found this graph for an S65 V8. Throttle % on left axis, gpm on right.

    Click image for larger version

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    I'll be talking to VAC later. Just checking here
    "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

    Das Beast build thread

    #2
    The numbers are around here somewhere, but I don't have them in front of me. Factory pump is pretty capable but IIRC you are going to want to make some changes probably before 350-400 HP, less if E85. Are you logging fuel pressure?

    For the record it is not too bad swapping to a big pump (I ended up with the DW400). At least on the early model it is a tight fit but you can get it into the tank. If you are running a fuel cell (can't recall, been a while since I went through your entire thread) it should be an even easier installation.

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      #3
      Oil pump gpm ... not fuel pump :-)
      "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

      Das Beast build thread

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        #4
        Originally posted by dvallis View Post
        Oil pump gpm ... not fuel pump :-)
        Man I am braindead... that is what I get for getting on R3V before the morning coffee...

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          #5
          I know they flow more than enough to provide 100psi+ of pressure at 7200rpm when the springs are shimmed lol.

          The vanos engines probably have more oil flow analysis done since they use the pressures for cam timing. The sXX engines have insanely high pressures.
          john@m20guru.com
          Links:
          Transaction feedback: Here, here and here. Thanks :D

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            #6
            LoL for sure.

            I'm considering dry sumping this thing. Worked with a engineer at Peterson Fluid Systems and put together the plan. Still chasing data points like gpm. Might just flow test the pump myself, since its on the bench now.
            "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

            Das Beast build thread

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              #7
              Sooo, all BMW pumps are pressure limited, and the earlier ones at about 60 psi, hot.

              An engine that's in the final stages of spinning a bearing still makes that at 2500 rpm.

              You can pretty easily figure the volume of the stock pump per rev
              (just cc it)
              and then multiply that by rpm, and derate maybe 25% for all losses.

              As to dry sumping, pretty much any dry sump pump out there is going to flow plenty-
              regulate it at 60 psi, make sure it makes 10 at idle, and then start using
              larger and larger pulleys until it doesn't!

              Then if it doesn't scavenge well enough, add more scavenge sections/volume.

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

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                #8
                Math reality check

                RPM x Displacement(in3) / 231 = gpm

                16.3871 cc/in3 so

                RPM x Displacement(cc) / 3785 = gpm

                I don't have a pump on front of me but the gear housing is about the size of a coke can in diameter, maybe an inch tall. Ballpark height 1/4 of 12 Oz coke can, say 3 Oz. That's about 90 cc. But most of the internal space is taken up by gears so say 3 cc.

                6500 x 3 / 3758 = 5 gpm x 0.75 = 3.75 gpm

                We're in the ballpark since an S65 flows 4 gpm.

                The Peterson pumps have a built in pressure regulator. We can dial that in to 60. They like to spin at 4500 rpm, so there will be a 21 tooth belt drive on the crank and 32 tooth on the pump. They use a belt like our timing belt.

                Will be a cool project.

                "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                Das Beast build thread

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