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    • Is the best N54 automatic transmission upgrade actually a DCT swap into an E9X 335i, E82 135i, or E60 535i?

      There are upgrades coming for the ZF 6HP21 gearbox (such as the Nizpro option) but is it too little, too late? BimmerBoost knows of a member who recently completed a DCT swap with upgraded clutches as well as a few other members doing the same thing.


      Details on the successfully completed swap along with install pictures, pricing details, and the performance increase will come in a later article but perhaps the best option for automatic N54's running too much torque has been around this whole time and provided by BMW themselves.

      The Getrag DCT unit that BMW sources is used in a variety of models. If you are wondering about the torque handling capability, just look at what kind of torque F10 M5's running upgraded turbos are putting out and how the DCT transmission with upgraded clutches is holding it.

      Not only is the DCT capable of higher torque capability than the ZF 6HP21 it does not have the same software issues holding it back or internal hardware capability issues. Some upgrades for the AT box only aim at making it not slip at fairly low power levels in this day and age of N54 tuning. In other words, a complete waste of time for people running big boost (or who intend to add power) and concerned with maximum performance. You know, the kind of people who read BimmerBoost.

      The truth is, the DCT is the best option for high powered N54's. Not only will it hold as much torque as you can throw at it you also get a shift speed benefit. It's quite simply the best performance option and the swap alone will improve performance without you even having to add any power. The E82 1M should have come from the factory with it.

      If you are looking into something like the Nizpro upgrade by the time you factor in shipping from Australia, part cost, software, install, and shipping you might as well have just swapped in the DCT and had the best of all worlds.

      Look forward to a detailed article on this swap coming up soon.

      This article was originally published in forum thread: Is the best N54 automatic transmission upgrade actually a DCT swap into an E9X 335i, E82 135i, or E60 535i? started by Sticky View original post
      Comments 68 Comments
      1. 135single's Avatar
        135single -
        What people with auto N54 need is a full detailed article that provides them with all the parts needed along with parts number+ pics if possible.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135single Click here to enlarge
        What people with auto N54 need is a full detailed article that provides them with all the parts needed along with parts number+ pics if possible.
        I understand. I intend to provide you with exactly that and all the details you need not to mention the people who actually can and have done this.
      1. bradsm87's Avatar
        bradsm87 -
        Agreed in general for street and circuit work. I'd do a DCT swap before spending the money on an AT hardware upgrade. For drag racing, auto wins though. You just can't load up and launch a DCT like you can an AT.

        With a flashed AT TCU, the AT should work a treat with firm, fast shifts for anything up to around 670NM.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        For drag racing, auto wins though. You just can't load up and launch a DCT like you can an AT.
        Disagree. You can't 'load up' because there isn't a torque converter to load. Instead, you use revs and the cpu modulates the clutches off the line.

        It's very effective. I never had any trouble drag racing my M3 and my Porsche is devastatingly quick off the line.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        fast shifts for anything up to around 670NM.
        Just to translate for people this is 494 lb-ft.

        He's right, it will firm up and hold up to that point. The thing is, how many N54 guys are beyond that point and need a better solution at those levels?
      1. bradsm87's Avatar
        bradsm87 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Disagree. You can't 'load up' because there isn't a torque converter to load. Instead, you use revs and the cpu modulates the clutches off the line.

        It's very effective. I never had any trouble drag racing my M3 and my Porsche is devastatingly quick off the line.
        I'm with you when it comes to N/A engines or engines with very minimal turbo lag. For larger turbos, you need to load the engine up on the torque converter for a second or so to get it to spooled and ready to release the brake.

        I'm more of a circuit racing and DCT fan myself.
      1. bradsm87's Avatar
        bradsm87 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Just to translate for people this is 494 lb-ft.

        He's right, it will firm up and hold up to that point. The thing is, how many N54 guys are beyond that point and need a better solution at those levels?
        My understanding is around 720nm even with Dodson clutches is around the limit for the DCT without slipping issues. BuraQ or trebila would know best as they've tuned a few.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        I'm with you when it comes to N/A engines or engines with very minimal turbo lag. For larger turbos, you need to load the engine up on the torque converter for a second or so to get it to spooled and ready to release the brake.
        You're referring to brake boosting essentially.

        When you rev up to, I don't know, 4500 rpm or so and engage the clutches aren't you going to have more than enough torque?

        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        I'm more of a circuit racing and DCT fan myself.
        I hear you. This would be a dream for 1M guys in that instance.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        My understanding is around 720nm even with Dodson clutches is around the limit for the DCT without slipping issues. BuraQ or trebila would know best as they've tuned a few.
        There are other upgrades and I don't know if you have to just swap in the 335is box or if you can go straight to one of the beefier boxes which are the same size.

        Regardless, you can go well past 720nm. The M5 shows this.
      1. bradsm87's Avatar
        bradsm87 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        You're referring to brake boosting essentially.

        When you rev up to, I don't know, 4500 rpm or so and engage the clutches aren't you going to have more than enough torque?
        Not without load.
      1. bradsm87's Avatar
        bradsm87 -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        There are other upgrades and I don't know if you have to just swap in the 335is box or if you can go straight to one of the beefier boxes which are the same size.

        Regardless, you can go well past 720nm. The M5 shows this.
        My inderstanding is that the 335is DCT is not the same as the M5 DCT.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        Not without load.
        I'm just not seeing any issues with boost when launching myself at those rpm ranges. When I get off the brake (and you have load) it just moves... hard. None of the turbo dual clutch cars are struggling off the line. They are actually quite a bit quicker/faster.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        My inderstanding is that the 335is DCT is not the same as the M5 DCT.
        Correct but it's the same physical box though with internal changes. These same internal changes can be made and even exceeded.
      1. 135single's Avatar
        135single -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        You're referring to brake boosting essentially.

        When you rev up to, I don't know, 4500 rpm or so and engage the clutches aren't you going to have more than enough torque?



        I hear you. This would be a dream for 1M guys in that instance.
        Currently i have e82 135i with built engine which runs single turbo setup and Level10 upgrades on the auto tranny. it is sad that you know that your engine can handle so much more than the current boost but the limitation the auto tranny can offer is making it hard and the options available still not worth the hassle. I personally think N54+DCT with the current upgrade options in the market is considered the best combination which is the reason why i got my self E89 Z4 with DCT (the only option i had with reasonable price) now i am running a project on it and soon it will have a single turbo setup along with Dodson sportsmanPlus DCT kit. My buddy owns e82 1M which he's working on swapping the manual with a DCT (i know to some it is a shame to touch the originality of such iconic car but to him he is in love with the difference in performance the DCT can offer).

        I was thinking to swap the DCT in the z4 with the auto on the 135i but still haven't found any workshop that is capable to go through that hassle. the beauty of the DCT is that you can find different solutions for it by well-known brands like Dodson and SSP. Again.. you will be posting a thread with a great solution and it would be just great if it includes detailed information from A to Z such as all parts number(priced if possible), programming, and photos. I mean it would be great if there is a business that offers the whole Auto to DCT solution.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135single Click here to enlarge
        I personally think N54+DCT with the current upgrades options in the market is considered the best combination
        I agree with you.

        Click here to enlarge Originally Posted by 135single Click here to enlarge
        Again.. you will be posting a thread with a great solution and it would be just great if it includes detailed information from A to Z such as all parts number(priced if possible),
        This is exactly what I am going to try to deliver. I can't promise it will be perfect but I'll do my best.
      1. Artsoasis's Avatar
        Artsoasis -
        Click here to enlarge Originally Posted by bradsm87 Click here to enlarge
        My understanding is around 720nm even with Dodson clutches is around the limit for the DCT without slipping issues. BuraQ or trebila would know best as they've tuned a few.
        That is not the case. 650whp and over 600wtq with no issues on stock clutch packs with 126k miles.
      1. R.G.'s Avatar
        R.G. -
        Click here to enlarge Originally Posted by 135single Click here to enlarge
        What people with auto N54 need is a full detailed article that provides them with all the parts needed along with parts number+ pics if possible.

        Literally on the first page

        http://www.bimmerboost.com/showthrea...CT-AT-gt-Metch
      1. R.G.'s Avatar
        R.G. -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        Is the best N54 automatic transmission upgrade actually a DCT swap into an E9X 335i, E82 135i, or E60 535i?
        Without a doubt DCT>AT

        That will be the next step in my build.
      1. Sticky2's Avatar
        Sticky2 -
        Click here to enlarge Originally Posted by R.G. Click here to enlarge
        Yeah that has great details but it is a few years old. There's a few things learned since then but still that's a great starting point.
      1. j_hynson's Avatar
        j_hynson -
        Im going with SSP clutches for my DCT swap. Finally started finding parts for a good price. For a second there, there were not many used parts up for grabs