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Thread: Turbo motor debate

  1. #1
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    Turbo motor debate

    Hello all!
    So with my turbo 2.7 build sort of wrapping up with my e30 I’ve decided to start looking into other motor options. I’ve come to the conclusion I think I’d like to purchase another motor with the intent of building a higher hp turbo motor on the back burner for a later swap. However the last few weeks I’ve done so much research I feel like it’s all leading me around in circles as to which motor is the best option. I’ve read countless threads on here, revlimited, bimmerfest, and more and it seems like the more I read the less I know. For me and most it seems to be between the m50nv, the m52, or the s5x platforms with me leaning more towards the m5x group. S54 will prolly be out of my price range for a while so I’d like to kind of take stepping stones with different “cheaper” BMW motors and their hp potentials if that makes sense that way I’m decently well rounded on forced induction as well as a few of the motors most people seem to do it with. So here it goes. I was pretty set on doing a turbo m50nv from a 91-92 e36 or e34. Start out simple and do a mls and studs with hx35 and see how far I get. However the more I read the more I see people going with the m52 because of the forged crank. I’ve also read that while the m52 may have a forged crank, the m50 has better rods. Also have read that m52 has a higher potential hp when built (not sure how truthful that is with a few on here making close to 800hp on a more or less stock bottom end m50nv). As for the m5x vs s5x debate, I think I’ve sold myself on the m5x platform based off the thicker cylinder walls that everyone is telling me about on every forum. However, that now loops me back to the m5x debate. Which would be your choice for a more longer term motor build where you’d shell out as much money as possible here and there and progressively build it over the years? M50nv or m52? I apologize in advance for a very repetitive thread that’s been covered countless times but I’m an eager mechanic who’s looking to broaden their turbo Bmw skills by trial and error over a few years with the help off everyone on here. Hope someone can point me in the right direction so I don’t lose my mind with research and just do a 2jz or ls swap like everyone else. Thanks very much.

  2. #2
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    Any motor you put together from the m5x platform will be really reliable as long as you aren’t running 40 psi on half mile runs.

    So pick your poison and enjoy.


    Sent from my iPhone using Tapatalk
    1989 535i - sold
    1999 M3 Tiag/Dove - sold
    1998 M3 Turbo Arctic/black - current
    2004 Built motor TiAg/Black - Sold
    2008 E61 19T Turbo-Wagon - current
    2011 E82 135i - S85 Swap - current
    1998 M3 Cosmos S54 swapped Sedan - current

    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  3. #3
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    The main reason people do M52's is they are cheap and they have an extra .3 liters of displacment which make a big difference. I have never seen or heard of a failure of the cast cranks in the m50's, but most people don't waste money in building them past just a junkyard build since if your getting forged pistons made it only makes sense to put a cheap m52 or m54 crank in it to get some displacement. The only real difference between the M50, M52, S50, and S52 is valve springs, bore and stroke, and vanos. They are all the same basic head and block casting. They all have strong and weak points but they are pretty moot points at the 600 whp and under kind of power levels. The strongest combination of stock parts is a mix of M50nv and M52 parts. The cutring gaskets have also made the larger bore motors reliable until you get into the extreme power levels where they start to crack cylinders.

    If you could give us a better idea on what kind of power numbers you want to make and how much you want to spend we can tell you exactly what to do. We have this pretty well figured out.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  4. #4
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    Thanks for all the info guys! Well my 2.7 should be in the 3-400 hp range ( closer to 400) so I was hoping to slowly build something to be in the 450-550hp range but also have room to grow if I ever get to that point and get tired of it yaknow. Most of my friends seem to be into the 2jz boat because it’s got endless capability but I feel as tho why waste all the money when I could spend it internally on a bmw motor and make near the same power goals. I’ve spotted a few m50nv in my area for reasonably priced but the more I read the more I turned away from it unfortunately cause I feel there’s so many different opinions on which is better.

  5. #5
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    Oh if thats all your looking for either an M50 or (vanos or non vanos) or an M52 from the junkyard will make that without even taking the oil pan off. Just get a stock m52 and get a cutring gasket (and spacer if you want to run pump gas) and a set of head studs and your done. You don't need to make life complicated until your looking for like 600+ whp.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  6. #6
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    Quote Originally Posted by MosesE30 View Post
    Thanks for all the info guys! Well my 2.7 should be in the 3-400 hp range ( closer to 400) so I was hoping to slowly build something to be in the 450-550hp range but also have room to grow if I ever get to that point and get tired of it yaknow. Most of my friends seem to be into the 2jz boat because it’s got endless capability but I feel as tho why waste all the money when I could spend it internally on a bmw motor and make near the same power goals. I’ve spotted a few m50nv in my area for reasonably priced but the more I read the more I turned away from it unfortunately cause I feel there’s so many different opinions on which is better.
    I think this platform has more potential than the 2jz.


    Sent from my iPhone using Tapatalk
    1989 535i - sold
    1999 M3 Tiag/Dove - sold
    1998 M3 Turbo Arctic/black - current
    2004 Built motor TiAg/Black - Sold
    2008 E61 19T Turbo-Wagon - current
    2011 E82 135i - S85 Swap - current
    1998 M3 Cosmos S54 swapped Sedan - current

    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  7. #7
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    The m50nv has more potential than the 2j? Or the m52

  8. #8
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    M52 w/ S52 cams is a fantastic low $ combo that will easily make a lot of power with just a compression lowering gasket and ARP head studs

  9. #9
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    Quote Originally Posted by MosesE30 View Post
    The m50nv has more potential than the 2j? Or the m52
    The bmw cylinder head with vanos has more potential.

    The blocks are very sturdy.

    Honestly if the platform had the attention I think it would be in a whole different place.


    Sent from my iPhone using Tapatalk
    1989 535i - sold
    1999 M3 Tiag/Dove - sold
    1998 M3 Turbo Arctic/black - current
    2004 Built motor TiAg/Black - Sold
    2008 E61 19T Turbo-Wagon - current
    2011 E82 135i - S85 Swap - current
    1998 M3 Cosmos S54 swapped Sedan - current

    1998 Turbo: PTE6870 | 1.15 ar | Hp Cover, Custom Divided T4 bottom-mount, 3.5" SS exhaust, Dual Turbosmart Compgates, Turbosmart Raceport BOV, 3.5" Treadstone Intercooler, 3.5" Vibrant resonator and muffler, Arp 2k Headstuds | Arp 2k Main studs | 87mm Je pistons | Eagle rods | 9.2:1 static compression, Ces 87mm cutring, Custom solid rear subframe bushings, Akg 85d diff bushings, 4 clutch 3.15 diff, , Poly engine mounts, UUC trans mounts W/ enforcers, 22RPD OBD2 Stock ECU id1700 E85 tune, 22RPD Big power Transmission swap w/ GS6-53

  10. #10
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    The m5x does have a better head stock vs stock, but neither are great and ported will flow pretty equally, upper 200’s. If you get really crazy porting on the m5x you run into the water jackets before you get to a really good port shape. The bottom end on a 2jz is in another league. Much heavier block and crank with bigger journals and the deck height is like an inch taller. The 2jz is closer in size to an s38.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  11. #11
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    Gotcha. Thanks for all the info. So basically what I’m gathering is that whether I choose m50nv or m52 I’ll have a good result and most likely make my power goals with a cometic hg and stud and good tune

  12. #12
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    No cometic, cutring.

    For what your wanting to do an m52 is the better choice. More displacement and vanos, it will make more power at every rpm and the tuning options are better.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  13. #13
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    That was another circle I got stuck in because I read the m5x Vanos motors were harder to tune or something along those lines because you had to use a VEMS unit or something similar which is what caused people to go the m50nv. Not sure how truthful that is but I was thinking by that time I could possibly recycle my ms2 from my current build for the motor but not sure if ms2 accommodates for Vamos applications. (Frankly haven’t started researching that yet to be honest).

  14. #14
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    That is not at all true. Yes you can run either motor off an ms2 including controlling vanos. There are some hardware modifications that need to be done to the Megasquirt board but it’s not a big deal. Lots of options for stock m52 ecu tuning as well. And there are plug and play ecus from megasquirt, vems, and link


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  15. #15
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    Gotcha! Guess I’m on the hunt for an m52 now! Thanks for all the insight and knowledge and for getting some of my research straight for me. Pretty defeating when everyone says research research research yet that research leads me in circles after doing so much. Anyways thanks so much for all the advice and I guess if I run into any research issues or questions I’ll be sure to revamp this thread up again.

  16. #16
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    Last question after some more research... I’m assuming the best m52 to turbo would be the m52b28? Seen people do the b25 but based off research I seem to come across countless more b28 builds. Am I correct in assuming that the b28 is the way to go with turbo applications? Read that compression was slightly lower on the b28’s and the stroke was slightly longer (84mm I believe in the b28’s). Thanks again and I believe that’s my final question now before I keep on researching myself to death.

  17. #17
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    Yes get a b28. Extra displacement and they are actually more common. 96 to 98 328i or 96 to 98 528i. You will also need and e34 525i oil pan and oil pump pickup to fit in your e30.


    86 325es, 2.8L m50, S476sxe, ProEFI 128 ecu, e85, solid rear axle, TH400 trans, 28x10.5w slicks, zip ties, popsicle sticks, tape
    best time 9.06 @ 151.8 mph, best 60 foot 1.30

  18. #18
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    Gotcha! Thanks again for all the info I believe all my questions have been answered now.

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