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Thread: M50 or M52 Cams?

  1. #1
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    M50 or M52 Cams?

    I see the part numbers are different but don't know any specs.
    I am using a M50tu head on my M52(in an E39) and have both sets of cams available.
    Which is preferred and why?
    Thanks

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  2. #2
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    09/90 E34 525i (M50)
    M50.
    The m52 made less power than the m50, probably smaller cams was one reason for it ( euro 2 emissions standards 1996 demanded a huge cut in CO). 141kw for m50b25, 125kw m52b25

    E: though maybe you won't get any benefit with an e39 DME?
    Last edited by fo3; 04-22-2019 at 10:42 AM.

  3. #3
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    Thanks, the M50 head is going on a M52b28. Lazy me is wanting to leave the M50 cams in place rather than swap the M52 ones. I'm always nervous when tightening down the caps for the cams.
    I was told once that the intake cams have same lift and duration but perhaps the profile was different.
    I have nothing on the exhaust cams, 11 31 1 738 371 in the M50tub25 and 1 703 892 in the M52b28

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  4. #4
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    09/90 E34 525i (M50)
    Not sure about exhaust, I thought they were all the same lift and duration for the whole Mxx series so it's weird you get different part numbers.

    "M52TU 228 inlet with 9.0mm lift 244 exhaust with 9.0mm lift, all engines" is what I found elsewhere but the m52b28 single vanos non TU is something I've never researched and always seems missing from any data.

    EG:
    M50B25NV – in 240º, 9.7mm; exh 228º, 8.8mm
    M50B25TU – in 228º, 9.0mm; exh 228º, 9.0mm
    M52B25TU – in 228º, 9.0mm; exh 244º, 9.0mm
    M52B28TU – in 228º, 9.0mm; exh 244º, 9.0mm
    M54B25 – in 228º, 9.0mm, exh 244º, 9.0mm

    Again, the m52 non tu is missing, but it can't be the same as m50b25TU since you've found different part numbers already. And it won't be the same grind as m52bxxTU as it isn't vanos.

    Edit:
    M50B20nv // int: 240º(9.7mm) // open:24º close:36º // exh: 228º(8.8mm) // open:38º close:10º
    M50B25nv // int: 240º(9.7mm) // open:19º close:41º // exh: 228º(8.8mm) // open:35º close:13º
    M50B20tu // int: 228º(9.0mm) // open:3º close:39º // exh: 228º (9.0mm) // open:39º close:9º
    M50B25tu // int: 228º(9.0mm) // open:4º close:44º // exh: 228º(9.0mm) // open:35º close:13º
    S50B30 // int: 260º(12.0mm) // // exh: 260º(12.0mm)
    S50B30US // int: 252º(10.2mm) // // exh: 244º(9.5mm)
    S50B32 // int: 256º(9.7mm) // // exh: 240º(9.0mm)
    M52B20 // int: 228º(9.0mm) // open:4º close:44º // exh: 228º(9.0mm) // open:39º close:9º
    M52B25 // int: 228º(9.0mm) // open:4º close:44º // exh: 228º(9.0mm) // open:39º close:9º
    M52B28 // int: 230º(9.0mm) // open:1º close:49º // exh: 228º(9.0mm) // open:39º close:9º
    S52 // int: 252º(10.2mm) // // exh: 244º(10.2mm)
    M52B20tu // int: 228º(9.0mm) // open:-6º close:54º // exh: 244º(9.0mm) // open:47º close:17º
    M52B25tu // int: 228º(9.0mm) // open:-6º close:54º // exh: 244º(9.0mm) // open:47º close:17º
    M52B28tu // int: 228º(9.0mm) // open:-6º close:54º // exh: 244º(9.0mm) // open:47º close:17º
    M54b25 // int: 228º(9.0mm) // // exh: 244º(9.0mm)
    M54b30 // int: 240º(9.7mm) // // exh: 244º(9.0mm)
    M54b30ZHP // int: 248º(9.7mm) // // exh: 248º(9.7mm)

    the m52b28 exhaust cam would be right at home in a 2L m50b20tu (Seriously though - I cross checked your part number in realoem and that's what they changed to for non vanos (exhaust) engines - even the m50b25TU - after 09/1994)
    Last edited by fo3; 04-23-2019 at 05:27 AM.

  5. #5
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    ^^ thanks! These are the intake specs?
    I think I'll use the b28 parts as they were intended for this application and the head casting is same # so all will be as intended. I was hoping not to mess with undoing the cams.
    C'est la vie.

    If you can leave two black stripes from the exit of one corner to the braking zone of the next, you have enough horsepower. - Mark Donohue

  6. #6
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    09/90 E34 525i (M50)
    These are full specs for everything, intake and exhaust specs as well as valve timing. Even though duration and lift are more or less always the same for these engines (m52b28 has 230* compared to m50b2tu 228* though), this shows overlap which is why there are different part numbers for cams even with the same lift and duration.
    Overlap is good for high rpm performance and power, but I think BMW were changing the overlap and valve timing for lower emissions and torque characteristics.

    eg m50b25tu inlet opens at 4* before TDC, closed at 39* after BDC; exhaust opens 35* before BDC, closes 13* after TDC means the exhaust and inlet are both slightly open for 17* overlap travel at the top.
    The m52b28 is 1* + 9* = 10* overlap

    E: In short if you don't want to mess with intake, DME or whatever I agree you should just fit the m52 cams. I just thought I'd research why you had different part numbers even though the NV exhaust cams should have been the same spec for all I knew before.
    Last edited by fo3; 04-23-2019 at 09:31 AM.

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