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M50 stroker help

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    M50 stroker help

    Hello everyone,
    So I just got a M50tu and an m52b28 crankshaft for pretty much free and would like to build a 2.8 stroker. I’ve been seeing tons of write ups on the m54 rotating assembly but not too much on the 2.8 setup unless it’s on the non Vanos motor which I believe has different cams and pistons. Can someone please help me figure out what combination of rods, pistons, and cams to use for something that will still run fine on pump gas. Motor will be going into my hennarot 318 ��

    #2
    I recently got my E30 back on the road after a complete refresh of the car and M50 stoker build/rebuild/swap. My setup used exactly the same parts as what you have now. You can look on my profile to see the threads I've started for more information. The basic recipe uses M52B28 crank and rods + M50TUB25 pistons. The block and head are normal single vanos M50 parts and I ended up doing a full rebuild with S52 Cams. The end result is a 2.8L with a 11.2~11.3:1 compression ratio.

    What you want are 135mm rods (M52B28 and other engines). The 84mm bore is shared between multiple engines, but the bump in compression over a stock M52B28 rotating assembly comes down to the wrist pin height in relation to the top of the piston. The M50TUB25 piston has the largest distance between the wrist pin and top of the piston.

    This website will be useful:
    https://www.e30zone.net/e30wiki/index.php?title=M5x
    Originally posted by Melon
    Engine work takes patience and finesse.

    Suspension work takes anger, a big fucking hammer, and a torch.

    Comment


      #3
      Thanks for the help. I’ve read a little bit about that setup before. How do you like it overall? Oh and lastly how do you think stock cams will feel on that setup. Cheers!

      Comment


        #4
        I can't really say I have enough experience to come to a definite conclusion since I have less than 200 miles on it, I've yet to go full throttle, and I haven't revved it past 5500 rpm. I'm just trying to break it in with the tune I have now before I get it on the dyno in the spring.
        However, it has plenty of torque down low, even at quarter throttle. It has more low end torque than a standard 2.5, which isn't a surprise with a longer stroke and higher compression. With the cams, it pulls harder and harder as the revs climb. Regarding using the stock cams, I don't think it'll be a problem since the cam profiles are the same for 2.5s and 2.8s. You may have less top end power, and more low end power than m3 cams, but that's just the standard effects of stock cams vs. upgraded cams. Again, I have custom software, but I think the dyno time in the spring may net me more low end power. I would recommend getting some sort of custom software regardless.

        All in all, if you have the parts lying around and you're rebuilding a M50 anyway, I see no reason why you shouldn't do it. A lot of people say "jUsT dO a S50 sWaP," but this is arguably cooler and you have a fresh engine for much less than the price of a S50 with 150k miles.
        Originally posted by Melon
        Engine work takes patience and finesse.

        Suspension work takes anger, a big fucking hammer, and a torch.

        Comment

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