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Thread: M50 manifold on an M52 2.5l?

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    M50 manifold on an M52 2.5l?

    I noticed that I have an M50 manifold from my parts car, and since I'm doing a transmission swap, I was thinking of taking the opportunity to replace my manifold with the M50. I think taking it off should make getting to the top transmission housing bolt easier if I take my manifold off anyway. So the question is will the M50 bolt right up to my head? I have a Super Sprint exhaust and K&N filter, and am putting in a set of Denso Iridium plugs. If the M50 will fit, I imagine the ECU should be able to adjust the fuel mixture, and should result in a few extra ponies...

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    yes, the m50 mani upgrade is good for 2.5, 2.8 m52 engines.
    1998 323is - m50 intake manifold / 328is exhaust / Shark Injector


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    Thanks Mr. Ilia.

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    BMW thought it worked great on the 2.5L M50 motor from 1992-1995 as well as the 3.0L M3 in 1995. I think the change to a small manifold was partly for emissions and partly because BMW thought lazy American drivers who short shift would be happier trading top end power for bottom end power.

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    Quote Originally Posted by pbonsalb View Post
    BMW thought it worked great on the 2.5L M50 motor from 1992-1995 as well as the 3.0L M3 in 1995. I think the change to a small manifold was partly for emissions and partly because BMW thought lazy American drivers who short shift would be happier trading top end power for bottom end power.
    Are you saying the M52 does better on the bottom end than the M50? I would find that surprising... usually more air flow allows for more power in the bottom end at the cost of fuel economy.

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    The M50 manifold is a popular upgrade for M52 and S52 powered E36s because the larger runners of the M50 intake manifold promote better high-RPM power, while sacrificing a negligible amount of low-end torque. It's best to pair the manifold with a tune at the bear minimum, and a larger throttle body and MAF to realize it's full potential.


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  7. #7
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    Quote Originally Posted by tock172 View Post
    The M50 manifold is a popular upgrade for M52 and S52 powered E36s because the larger runners of the M50 intake manifold promote better high-RPM power, while sacrificing a negligible amount of low-end torque. It's best to pair the manifold with a tune at the bear minimum, and a larger throttle body and MAF to realize it's full potential.
    What are your recommendations for a larger throttle body and MAF? Are those parts that can be pilfered from other cars as well, or do I have to go aftermarket?

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    Quote Originally Posted by navvid View Post
    I noticed that I have an M50 manifold from my parts car, and since I'm doing a transmission swap, I was thinking of taking the opportunity to replace my manifold with the M50. I think taking it off should make getting to the top transmission housing bolt easier if I take my manifold off anyway. So the question is will the M50 bolt right up to my head? I have a Super Sprint exhaust and K&N filter, and am putting in a set of Denso Iridium plugs. If the M50 will fit, I imagine the ECU should be able to adjust the fuel mixture, and should result in a few extra ponies...
    You have an m52tub25, not exactly the same as the m50b25. You have an e46 motor, so a better alternative is using the m54b30 intake manifold.

    Suspension: Bilstein Sports, GC Coilover conversion, IE Subframe Bushings, IE RTABs, M roadster sways, M roadster front control arms, M roadster Front calipers/hubs.
    Engine/Driveline: M54B30 intake Manifold, Dinan CAI, ZHP Cams, Headers, Underdrive pulleys, Conforti Software, 3.46 diff.

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    That is a very good point. I don't know much about the M52TU and M54 motors. We had an M52TU in our 99 528i, but it was 2.8L and I left that car stock. If an M54 3.0L will bolt in and you can swap ECU or tune yours for it, that would be the way to go if you are up for a project and can find a used 3.0L cheap. A 2.5L in a 3000+ lb car will never be quick unless it is turbocharged and I have read that studs can pull out of turbocharged aluminum blocks like the M52TU and M54 blocks.

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    Unfortunately, I don't have the time or resources for a motor swap right now. Given my circumstances, I have to go with the most economical solution which will get me rolling. I just happened to have a M50 intake laying around. But what about throttle bodies and MAF's? What's the biggest, highest airflow throttle body and MAF I can easily and affordably acquire? How about those parts from the 325? Do those also provide higher airflow than the ones that came on my M52TUB? TB/MAF from another car? Aftermarket?
    Last edited by navvid; 04-21-2015 at 11:10 AM.

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    Quote Originally Posted by pbonsalb View Post
    That is a very good point. I don't know much about the M52TU and M54 motors. We had an M52TU in our 99 528i, but it was 2.8L and I left that car stock. If an M54 3.0L will bolt in and you can swap ECU or tune yours for it, that would be the way to go if you are up for a project and can find a used 3.0L cheap. A 2.5L in a 3000+ lb car will never be quick unless it is turbocharged and I have read that studs can pull out of turbocharged aluminum blocks like the M52TU and M54 blocks.
    An m54 swap is not hard, but there are some tricks to it. I am not talking entire motor (I have an m52tub25 in my z3). It shares a lot of parts with the m54, same block, head etc. So all internals are interchangeable, cams, and the intake manifold as well. The 3.0 intake manifold from a 330 is a cheap upgeade. Mine was 50 bucks for the manifold. I am also running zhp cams, which makes a nice difference. The biggest difference is the throttle, both are drive by wire (in a way) but very different assemblies and throttle bodies. So an adapter plate is needed for the manifold swap (turner motor sports makes one).

    I think it is a worthwhile mod.

    Suspension: Bilstein Sports, GC Coilover conversion, IE Subframe Bushings, IE RTABs, M roadster sways, M roadster front control arms, M roadster Front calipers/hubs.
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    Quote Originally Posted by navvid View Post
    What are your recommendations for a larger throttle body and MAF? Are those parts that can be pilfered from other cars as well, or do I have to go aftermarket?
    Factory intake with an M50 manifold and a Riot Racing big bore throttle body, which outperforms the more expensive Dinan unit. Porsche 3.5" HFM. TRM tune to ensure everything operates in harmony.

    No matter how you slice it, it isn't cheap. The M50 manifold is around $50, the tune is $400, MAF is $400 and the throttle body is $265.


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    Quote Originally Posted by tock172 View Post

    Factory intake with an M50 manifold and a Riot Racing big bore throttle body, which outperforms the more expensive Dinan unit. Porsche 3.5" HFM. TRM tune to ensure everything operates in harmony.

    No matter how you slice it, it isn't cheap. The M50 manifold is around $50, the tune is $400, MAF is $400 and the throttle body is $265.
    He has an m52tu not a normal m52, 1999 323is had an e46 motor, so an M50 conversion while possible, will not exactly be the same easy labor. The throttle body will not work at all, as his throttle is drive by wire (cable +dbw at the throttle body).

    The only thing he can do for a larger throttle body is bore it out, or the very expensive conversions to m54 or possibly all out cable conversion, but not cheap.

    Suspension: Bilstein Sports, GC Coilover conversion, IE Subframe Bushings, IE RTABs, M roadster sways, M roadster front control arms, M roadster Front calipers/hubs.
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    - - - Updated - - -

    Quote Originally Posted by Luftwaffe1O1 View Post
    You have an m52tub25, not exactly the same as the m50b25. You have an e46 motor, so a better alternative is using the m54b30 intake manifold.
    No, this is incorrect.

    The M54 manifold will not fit his 99' E36 equipped with a M52B25. The 323is M52s are unique to the E36 chassis and are not similar to the E46 cars which have Dual VANOS.

    The M50 manifold WILL fit and will provide gains as others have stated.

    Furthermore, the 99' 323is does not use drive by wire.

    M50 installed on my 1999 323is with stock TB, etc:


    For Reference:
    Link: http://forum.e46fanatics.com/showthread.php?t=341490

    1992 325 - M50b25
    1993-1995 325 M50b25tu (I think, 1992 had no vanos, 93-95 had single vanos)
    1992-1995 318 M42b18

    1996 got OBD-II

    1996-1998 328 M52b28
    1996-1998 318 M44b19

    Nows the tricky part, the E46 sedan came out for the 1999 model year, so-
    1999 328i has an M52b28tu
    1999 323i has an M52b25tu
    but
    1999 328is (coupe) is M52b28
    1999 323is is an M52b25

    Then for E46's, the 323 and 328 were made 1999 and 2000
    Those were both M52b28tu's or M52b25tu's.
    Last edited by BuddaLun; 04-21-2015 at 11:47 PM.

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    Quote Originally Posted by BuddaLun View Post
    - - - Updated - - -

    No, this is incorrect.

    The M54 manifold will not fit his 99' E36 equipped with a M52B25. The 323is M52s are unique to the E36 chassis and are not similar to the E46 cars which have Dual VANOS.

    The M50 manifold WILL fit and will provide gains as others have stated.

    Furthermore, the 99' 323is does not use drive by wire.

    Reference:
    Link: http://forum.e46fanatics.com/showthread.php?t=341490

    1992 325 - M50b25
    1993-1995 325 M50b25tu (I think, 1992 had no vanos, 93-95 had single vanos)
    1992-1995 318 M42b18

    1996 got OBD-II

    1996-1998 328 M52b28
    1996-1998 318 M44b19

    Nows the tricky part, the E46 sedan came out for the 1999 model year, so-
    1999 328i has an M52b28tu
    1999 323i has an M52b25tu
    but
    1999 328is (coupe) is M52b28
    1999 323is is an M52b25

    Then for E46's, the 323 and 328 were made 1999 and 2000
    Those were both M52b28tu's or M52b25tu's.
    My apologies, I figured they wouldn't bother creating two separate engines with similar naming in the same year. Sorry for the incorrect info.

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  16. #16
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    One question is how much of a choke point is the small stock manifold on the late 2.5L? We know swapping adds power on larger displacement motors, but those motors need more air. Same goes for the throttle body. And the exhaust. If you do decide to go ahead with these parts, also consider moving to the S52 cams, which have shown gains on the 2.8L motors. Dyno when you are done. I am curious what the 2.5L will do.

  17. #17
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    Quote Originally Posted by Luftwaffe1O1 View Post
    My apologies, I figured they wouldn't bother creating two separate engines with similar naming in the same year. Sorry for the incorrect info.
    No worries. The 323is is confusing in many regards. BTW, did you see how clean my engine bay is for a 16 year old car? This is what I really wanted people to notice but sadly, no one did.


    - - - Updated - - -

    Quote Originally Posted by pbonsalb View Post
    One question is how much of a choke point is the small stock manifold on the late 2.5L? We know swapping adds power on larger displacement motors, but those motors need more air. Same goes for the throttle body. And the exhaust. If you do decide to go ahead with these parts, also consider moving to the S52 cams, which have shown gains on the 2.8L motors. Dyno when you are done. I am curious what the 2.5L will do.
    Well if you look at the pic I posted above you can compare the M50 intake manifold runner size to the M52; the M50 manifold clearly has MUCH larger runners. I do not think the throttle body is much of a choke point since it is the same TB as used on the 3.2L USDM S52. The exhaust however on the 323is is problematic. The exhaust midsection on the 323is (which houses cats, etc) is the same used on the 4 cyl. E36s of the time (318,etc). However, the exhaust manifold (headers) coming off the engine are the same as the 3.2L USDM S52. So, in my mind, this is a choke point. A common mod for 323is guys is to run the 3.2L or 2.8L (97+ E36 M3 or 97+ E36 328i/is) midsection with an M3, 328, or aftermarket exhaust. Cams is another step further down the rabbit hole and would likely require tuning to get the most out of them, but here you have really moved out of the realm of "bolt on" mods.

    My 323is has:

    M50 Intake manifold
    98 3.2L M3 Exhaust Midsection
    M52 2.8L (328is) Exhaust
    3.23 E36 M3 LSD
    M Roadster Intake Boot (removes ASC and is a smooth bend)

    I REALLY wish I would have done below and after dynos to see how the power truly shifted and what the A/F is doing. However, I can say that the car is quicker, smoother, pulls all they way to redline (rather than dying at about 6k as it did in stock form) and the MPG has increased (assuming I drive conservatively).
    Last edited by BuddaLun; 04-22-2015 at 11:13 AM.

  18. #18
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    FWIW only the 98 M roadster intake boot is an ASC delete. The other years had ASC/DSC

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    Quote Originally Posted by BimmerBreaker View Post
    FWIW only the 98 M roadster intake boot is an ASC delete. The other years had ASC/DSC
    Yes, this is exactly right. OE part no:
    13541703588

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    Wow, this suddenly took off and became a great thread. Keep the info and suggestions coming. All are much appreciated, and will receive due consideration.

    It looks like a lot of my target parts are going to come from 96-98 M3/328. Did these models have all the air flow plastics in common?

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    Quote Originally Posted by navvid View Post
    Wow, this suddenly took off and became a great thread. Keep the info and suggestions coming. All are much appreciated, and will receive due consideration.

    It looks like a lot of my target parts are going to come from 96-98 M3/328. Did these models have all the air flow plastics in common?
    Some parts will come from the OBDII M3/328 except the M50 manifold and M Roadster intake boot.

    The OBDII M3/328 and your 323is share the same intake path in OE form. The OBDII M3/328 exhaust midsections are the same. M3 has different exhaust as compared to 328.
    Last edited by BuddaLun; 04-22-2015 at 04:39 PM.

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    Quote Originally Posted by navvid View Post
    Are you saying the M52 does better on the bottom end than the M50? I would find that surprising... usually more air flow allows for more power in the bottom end at the cost of fuel economy.
    Increased displacement almost always produces more HP/Torque.

    At lower engine speeds, the engine requires less air volume. Lower volume of air flows better in a smaller port, generally creating better volumetric efficiency with a smaller volume flowing faster in a small port. An over simplification, but that is the idea.
    Last edited by bluptgm3; 04-22-2015 at 04:24 PM.

  23. #23
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    Cams bolt on. A couple of hours if you know what you are doing. You want cams if running an M50 manifold. Otherwise you are losing bottom end power and your cams are falling off before rpm get high enough so you need the better breathing of the M50 manifold.

    I swapped the M50 onto my 99M3 in 2005, added headers, Shrick cams, midpipe, rear exhaust, tune, supercharger, LTW flywheel with HD clutch, etc., and then changed to turbo in 2010. I was over 600 rwhp last year and am looking for more this year. When I started, I figured 300 would make me happy.

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    Quote Originally Posted by bluptgm3 View Post
    Increased displacement almost always produces more HP/Torque.

    At lower engine speeds, the engine requires less air volume. Lower volume of air flows better in a smaller port, generally creating better volumetric efficiency with a smaller volume flowing faster in a small port. An over simplification, but that is the idea.
    I think it was a very apt explanation. I studied physics, and I don't think I could have said it any better. Cheers.

    - - - Updated - - -

    Quote Originally Posted by BuddaLun View Post
    Some parts will come from the OBDII M3/328 except the M50 manifold and M Roadster intake boot.

    The OBDII M3/328 and your 323is share the same intake path in OE form. The OBDII M3/328 exhaust midsections are the same. M3 has different exhaust as compared to 328.
    Was I correct about the year range? Are there any other cars that have compatible, desirable intake/exhaust parts? I am trying to widen the scope of my search.

  25. #25
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    Quote Originally Posted by navvid View Post



    Was I correct about the year range? Are there any other cars that have compatible, desirable intake/exhaust parts? I am trying to widen the scope of my search.
    96-99: M3
    96-98: 328
    99: 328is

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