FMU’s New E46 M3 Velocity Stacks

FMU’s New E46 M3 Velocity Stacks

We teased ’em the day before Tuner Galleria. We even had them in a shot in our post-Galleria write-up. But now you can see the whole deal, right here.

The new Fluid MotorUnion E46 M3 velocity stacks are decidedly the most ostentatious piece of equipment that we’ve put out lately. The main features of the velocity stack setup (just the stacks, without the extra rigging for the nitrous injection) are the aluminum stacks and the clamps. Having used various thin metal screw/operated clamps on previous versions of our velocity stack setups, we decided to approach this from a new direction. Previous clamps were flimsy, tough to position right and since they’re universal, don’t provide for the cleanest or most professional-looking fit. We sidestepped all that by creating a new style of clamp to use specifically for this engine. The round clamps have a single point of tightening on the end and are solid all-around, and they look more like part of the stack than something used to hold the stack in place. The two pictures that follow are of the velocity stacks and clamps, without all the extra nitrous rigging:


This setup below not only utilizes our new stack and clamp designs, but also a set of arms meant to deliver a wet shot of nitrous directly into the stacks when the butterfly valves are wide open. Putting all these pieces into the same engine bay creates a metallic jungle lurking underneath the hood, ready for any adventurous person to lean in and start exploring. And at first glance, it seems that there’s an awful lot going on. And you’re right, there is.

The tray for holding the nitrous setup is also made of aluminum, as are the arms pointed into the stacks. All these pieces were cut to our specifications in-house on the CNC mill, and run through the vibratory finisher to remove any sharp edges. The hard lines for the nitrous and gas were too small for a brake line bender, so we spent time (and many swollen fingers) manually bending the lines to fit in the exact positions we needed them; to make matters even more difficult, for a setup like this to operate correctly, each individual hard line has to be of equal length, making the routing an exercise in patience.

Despite all the frustration in assembling such a creation, stepping back to look at it after the build makes us realize that it was totally worth it. Here are the glamour shots, no teasing this time:


At this point, it’s only natural to offer up props to the company that helped us make this whole setup possible – Wizards of NOS, based out of the UK, supplied us with the nitrous equipment, and it included everything we needed for operation (including the nitrous itself, which came in an enclosure the size of an acetylene tank!). Knowing all the science behind this beautiful design makes us appreciate it even more, so much in fact that we want to replicate as many of these as we can.

If you’d like to inquire about purchasing a set of these stacks (with or without the nitrous rigging), feel free to shoot your humble narrator an e-mail. He can be reached at andrew [at] fluidmotorunion [dot] com. We’ve got some more ideas for Dick Cook’s M3 right now, and we’re excited to keep moving forward on future product development for the E46. Keep your eyes here for any updates on future Fluid MotorUnion products!

  • eric
    Posted at 19:18h, 10 March

    thats just crazy mann.. great work

  • a son
    Posted at 21:42h, 05 April

    real sick, tune it and post some videos, probably sounds insane….

  • Jeremy Carlile
    Posted at 16:04h, 19 September


    I am a deployed Soldier who will be returning home to Germany very soon. I own a 2003 E46 M3 (obviously) and wanted to know what a base velocity stack would cost and would also like to know about how I would get it installed, ie. can a bmw dealership do it or should I take it somewhere else. I have limited funds and therefore must make decisions about what I do to my car and when. However, i really like the velocity stack and have put it on my list of mods that I would like to do to my car. Please advise when able. Thanks for your time.

  • Al Hughes
    Posted at 05:51h, 15 December

    Hey guys

    Great work.

    As above is there a set price for this kit? and also will it need a standalone ecu or can it be just flash mapped? There is an e46 m3 in the uk with this kit and am very interested in it for an e36 aswell as an e46.

    Mmany thanks and keep up the good work.

  • Dharm
    Posted at 08:02h, 02 January

    Hi Love what you guys have done i’ve got a E46 M3 2002 would like the whole kit less the nos bottle how much would it cost? How much would it cost to post to London UK?

  • fluidmotorunion
    Posted at 11:56h, 02 January

    Dharm, we’ve forwarded your e-mail to the correct person at FMU, and they’ll have a response for you soon!

  • Jeremy Carlile
    Posted at 12:51h, 12 January

    The work is amazing. How much for the kit minus the nos. I have a 2003 E46 M3. Please advise how much the base kit would cost. Thanks.

  • angel
    Posted at 21:09h, 16 February

    good evening i was wonder if this set up with the stacks and nos kit run for and how much for the stacks alone how? would u recommended it for an all motor only?

  • Ricardo Rocha
    Posted at 21:53h, 06 November

    How much do the stacks cost? What must be done to the computer to bypass the MAF? How much power do they average on a stock s54?

  • Oliver
    Posted at 10:58h, 06 September

    Interested in this kit price please

  • fluidmotorunion
    Posted at 12:34h, 16 September

    Shoot an Email over to with stack questions.

  • Jamie millar
    Posted at 18:35h, 17 June

    Hi there could you provide a price for the stack set, do you have individual filters designed also, out of curiosity.


  • fluidmotorunion
    Posted at 15:18h, 20 June

    Jamie, unfortunately we never developed filters for these so at this time you would have to run them open.

  • Jamie Millar
    Posted at 06:30h, 30 June

    What’s the cost of just the stacks? Cheers they look stunning.

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