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Thread: S54 crank interchangeability

  1. #1
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    S54 crank interchangeability

    I've been brainstorming about my next project and I've ran into a bit of an issue. Im pretty sure my next project will have an S54 but the piston speeds are way too high for what I want to do with it.

    Is there another crank with lower stroke that is swappable with the S54 crank? I haven't seen any definite answers on this. The other option is to have the S54 crank offset ground to destroke it but I'd hate to modify a crank if there are drop ins available.

  2. #2
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    Try someone like member PEI330ci. He might have some ideas. I have a very vague recollection of someone swapping an M50/52/S50/52 crank into an S54, but do not remember the details or reasoning.

  3. #3
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    I just used a S54 crank, rods and pistons. Machine shop had to shave a little here and there to fit it all but nothing major or more than 2mm. I have M50B25 non-vanos.

    - - - Updated - - -

    Apologies I wrongly interpreted your post. I actually used the M54 (B30) crank which is interchangable with the M50B25 crank. With that I know the M50B25 crank could fit =75mm stroke, and i believe the M52B28 crank could also fit =84mm, for M54B30, which has a stroke of 89.6mm, maybe the latter (M54 crank) can work for the S54.

    Good luck with the project!

    M50B25 crank = 75mm
    M52B28 crank = 84mm
    M54B30 crank = 89.6mm
    S54B32 crank = 91mm

  4. #4
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    i thought VAC used to sell a destroked crank for S54, but it will be spendy made by arrow in UK i gather

    i know MM used to use S54 cranks offset ground to 93mm stroke and put them into a S52 engine perhaps you could could do the reverse and use a M52b28 crank or similar and modify the snout or pulley but could be risky with harmonic issues that area is a weak point especially given you sound like you want to spin the engine up really high....

    are you sure you cant deal with the stock s54 crank?

    maybe check out the S50B30euro version?
    Last edited by digger; 12-28-2016 at 09:51 PM.

  5. #5
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    There is a crank snout adapter floating around here (some member was making/selling them) that permitted an M50/M52/S50/S52 crank to be used in the S54. I'll try and find it.

  6. #6
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    Quote Originally Posted by digger View Post
    i thought VAC used to sell a destroked crank for S54, but it will be spendy made by arrow in UK i gather

    i know MM used to use S54 cranks offset ground to 93mm stroke and put them into a S52 engine perhaps you could could do the reverse and use a M52b28 crank or similar and modify the snout or pulley but could be risky with harmonic issues that area is a weak point especially given you sound like you want to spin the engine up really high....

    are you sure you cant deal with the stock s54 crank?

    maybe check out the S50B30euro version?
    I've seen the VAC setup. It would be awesome to have a custom billet crank but I imagine that would cost about as much as the vehicle. I've had cranks for other engines I've built welded and offset ground for under $1000 and those were V8s.

    I've built quite a few high performance engines and I have certain thresholds in my mind when starting projects and the piston speeds on the S54 are an immediate red flag. This project will be a big number FI setup so priority number one will be bullet proofing. Everything else in the engine will be built including custom rods and pistons, vanos delete, solid lifters titanium valve train, etc. It would be nice to undo the shit decision BMW made when they stroked out the s54 to be able to put bigger numbers on their window stickers.

    In my mind I'll trade the 50hp difference in stroke for it to stay together at an additional 300hp.

    - - - Updated - - -

    Quote Originally Posted by jakermac View Post
    There is a crank snout adapter floating around here (some member was making/selling them) that permitted an M50/M52/S50/S52 crank to be used in the S54. I'll try and find it.
    I remember seeing that but I can't remember how I got to it. If I remember correctly its production wasn't certain. I have access to full machining capabilities so if nothing else I wouldn't mind getting some dimensions.
    Last edited by SilverBurner; 12-29-2016 at 05:33 AM.

  7. #7
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    What is your target rwhp with the FI S54?

  8. #8
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    Quote Originally Posted by SilverBurner View Post
    I remember seeing that but I can't remember how I got to it. If I remember correctly its production wasn't certain. I have access to full machining capabilities so if nothing else I wouldn't mind getting some dimensions.
    I did some searching but didn't find it. If I recall correctly, contacting the seller was a bit troublesome as well.

  9. #9
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  10. #10
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    Quote Originally Posted by pbonsalb View Post
    What is your target rwhp with the FI S54?
    You know I'm not really sure at this point. I haven't taken the time to run the numbers on turbine efficiency yet with end displacement not for sure. I imagine somewhere around 700-800hp.

  11. #11
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    Why do you need a shorter stroke with 700-800 rwhp when no one else does? I was thinking maybe you were building a 1000 rwhp monster.

  12. #12
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    If you are boosting it and are afraid of piston speeds, why not just limit the revs to a lower number?
    E36 M3 S50B32 daily - E36 M3 S54 trackcar

    They Say Money Talks, All Mine Ever Says Is Goodbye

  13. #13
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    The application will require this modification.

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