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Trent's S54 Rebuild and Sedan Swap

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    Trent's S54 Rebuild and Sedan Swap

    Hi all,

    I've been incredibly happy to find this forum. My heart was a bit broken after the other forum went away, but thanks to all of you that have resurrected this - it's incredible! I previously owned a 2001 IR/Black coupe that I had a lot of fun with. Evolve CSL box, Ground control Coilovers, etc.

    Was a lovely car!





    Fast forward through marriage, kids, and a decade... I'm looking to have some fun again. This time I'd like to get my hands dirty with a project. I considered a 1M S65 clone, but after owning an E91 I always remembered the E46 with more enthusiasm. So, E46 it is - onward!

    Here's the dirty one:



    Here's the very clean recipient of the engine, transmission, suspension, etc. :





    I picked up the 2002 M3 vert in tattered, but running condition. It has 211k miles and the HG was blown in varying degrees across every cylinder. It's also SMG - that will be swapped... eventually.

    My plan was to pull the head and have it decked and rebuilt, but that was not in the cards. I found that the HG failed on the block side first which means some small amount of material has been removed from the block where the HG initially failed. So, likely it is time to pull the whole lump and tear it all down to rebuild it to a further degree.

    And here we are after a week of toiling.












    #2
    Here is the offending issue - it catches on the finger nail and is recessed. I've removed all the carbon and this is what's left.



    I have a few, likely dumb, questions for the group, if I may... Humor me, please.

    1 ) Is it customary to reuse pistons in the stock bore at this mileage? If the bores are round and straight could it be honed with new rings installed?
    2 ) A bit obvious, but that small nick between the cylinders most certainly will lead to an early failure and needs to be decked/skimmed?
    3 ) Would the corrosion alone around the coolant jackets necessitate a deck/skim?
    4 ) In general, what is the best ROI I can get for my use case below?

    Because I was not planning on this I'm a bit on my heels with the direction to take with the pistons and block - I'd greatly appreciate some feedback and opinions.

    Some context - this will not be a track car. It will be a canyon/project/fun car that I build up over time. Not a daily either - used when I feel like it. Somehting I can fly under that radar in and also experience that glorious CSL intake roar when put the skinny pedal against the floor. So, does it need to be in 100% tip-top shape? No. Would I like it to be reliable for another 50k miles? Yes. It would likely take me a decade to accumulate that kind of mileage. I will take it apart and measure everything. If it's out of spec I will replace as needed. I intend to assemble the engine myself which I have done for dirt bikes, but never anything of this size/complexity. I look forward to the challenge. I will sub out the machine work.

    I am looking to borrow or rent bore gauges as that's one of the few things I don't have. If you have them I'd be happy to treat them as if they were mine and shower them with care!

    Thanks all and it's great to be back here :-)
    Last edited by tlow98; 06-22-2022, 10:28 PM.

    Comment


      #3
      1) For stock power, reusing the pistons should be fine as long as the pre-det did not damage them and the skirts and rings are still fine. Mahle Power Pack pistons are 1000 for a set.
      2) Due to the damage, safe option would be to deck the block and skim the cylinder head.
      3) A deck should take care of this
      4) A refresh like this should go another 100-150k street miles

      In this DIY - , the owner had the machine shop skim the head 0.16mm to get rid of a mark on the cylinder head. He states that 0.3mm is probably the upper limit and a few manufactures make thicker head gaskets for these engines as well. Best to stick with the stock Elring head gasket if you can.

      Edit: Headgasket DIY link - https://forums.m3cutters.co.uk/threa...e46-m3.205525/

      Good luck with the build
      Slideways
      Senior Member
      Last edited by Slideways; 06-23-2022, 04:00 PM.

      Comment


        #4
        Originally posted by Slideways View Post
        1) For stock power, reusing the pistons should be fine as long as the pre-det did not damage them and the skirts and rings are still fine. Mahle Power Pack pistons are 1000 for a set.
        2) Due to the damage, safe option would be to deck the block and skim the cylinder head.
        3) A deck should take care of this
        4) A refresh like this should go another 100-150k street miles

        In this DIY - , the owner had the machine shop skim the head 0.16mm to get rid of a mark on the cylinder head. He states that 0.3mm is probably the upper limit and a few manufactures make thicker head gaskets for these engines as well. Best to stick with the stock Elring head gasket if you can.

        Edit: Headgasket DIY link - https://forums.m3cutters.co.uk/threa...e46-m3.205525/

        Good luck with the build

        Thank you. This is very thoughtful and very helpful.

        Question - do the Mahle Pistons require aftermarket con rods? They say they have 21mm wrist pins. I’m wondering if the OE wrist pins are different since they call this out?

        That UK-based link is great. It’s been my guide up until I discovered the block issue and realized I’ll be going further than expected down this path, ha!

        He had basically the same issue I did, only on the head side.

        Comment

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