• VAC Motorsports Stage 3 N54 ported cylinder head dyno with aftermarket single turbo

      The N54 cylinder head is not exactly what one would call BMW's best work and it was never designed with top end power in mind. There is room for improvement in breathing up top and this is a large benefit for N54 owners who switch to a larger turbo such as an aftermarket single turbo conversion. This particular N54 motor has such a single turbo setup and as you can see it benefits up top greatly from the VAC Stage 3 cylinder head.

      Now, there is a bit of a trade off in torque down low. From 3000 to roughly 5252 rpm where torque and horsepower intersect on the graph the stock head has an advantage. Past 5000 rpm though the ported cylinder head shows torque gains and a flatter curve not dropping off nearly as hard as the OEM design. It breathes much better up to and past the stock redline showing over 600 horsepower on the dyno.

      This is definitely a modification for top end horsepower but that is generally an area of weakness on the N54. Plus, if going for all out performance the RPM drop after each shift at redline is not going to have one sitting at low RPM anyway. This cylinder head will shine with a single turbo in a roll on race.

      No word on pricing but it is nice to finally see some data from VAC on their N54 cylinder head work.

      This article was originally published in forum thread: VAC Motorsports Stage 3 N54 ported cylinder head dyno with aftermarket single turbo started by Sticky View original post
      Comments 95 Comments
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge
      1. Flinchy's Avatar
        Flinchy -
        awesome! finally some numbers from VAC

        would be good if there were actually flow bench numbers, but this is a start lol.

        might be nice if they ran the stock head to 7k though... it's obviously not BADLY dropping off. IMO it's a slightly dishonest way of making the stage 3 head appear better than it really is (which is plenty still) imo.... Blue peak to red at the same point looks like.. 40whp to me?.. if they'd carried blue through as well, it might even be 60 odd, with how much it's tapering.

        ED:... wtf.. what's with the dyno model? carolina? i have no idea how to relate these results then.
      1. lulz_m3's Avatar
        lulz_m3 -
        Click here to enlarge Originally Posted by Flinchy Click here to enlarge
        awesome! finally some numbers from VAC

        would be good if there were actually flow bench numbers, but this is a start lol.

        might be nice if they ran the stock head to 7k though... it's obviously not BADLY dropping off. IMO it's a slightly dishonest way of making the stage 3 head appear better than it really is (which is plenty still) imo.... Blue peak to red at the same point looks like.. 40whp to me?.. if they'd carried blue through as well, it might even be 60 odd, with how much it's tapering.

        ED:... wtf.. what's with the dyno model? carolina? i have no idea how to relate these results then.
        Its an engine dyno dude.

        That head is definitely breathing a lot better up top. On top of better numbers in the higher rev range, you can also see it made those numbers with slightly less boost. Very nice indeed!
      1. MDORPHN's Avatar
        MDORPHN -
        Good stuff! Any info on the single turbo set-up?

        Neil
      1. lulz_m3's Avatar
        lulz_m3 -
        Click here to enlarge Originally Posted by MDORPHN Click here to enlarge
        Good stuff! Any info on the single turbo set-up?

        Neil
        I'm going to assume it was the same one VAC posted about previously -

      1. mjmarovi's Avatar
        mjmarovi -
        So, am I looking at this right? 100bhp gain from just the ported heads? I would think this would help spool, but am I wrong in thinking this?
      1. MDORPHN's Avatar
        MDORPHN -
        Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
        I'm going to assume it was the same one VAC posted about previously -
        That'd make sense! Thanks.

        Neil
      1. lulz_m3's Avatar
        lulz_m3 -
        Click here to enlarge Originally Posted by mjmarovi Click here to enlarge
        So, am I looking at this right? 100bhp gain from just the ported heads? I would think this would help spool, but am I wrong in thinking this?
        Yes. Stock head is designed to spool a turbo as fast as possible, which is why it is restrictive at higher RPM's. Generally speaking, anything you do to make your engine breathe better up top is going to increase lag down low.
      1. Flinchy's Avatar
        Flinchy -
        Click here to enlarge Originally Posted by lulz_m3 Click here to enlarge
        Its an engine dyno dude.

        That head is definitely breathing a lot better up top. On top of better numbers in the higher rev range, you can also see it made those numbers with slightly less boost. Very nice indeed!
        that was my first thought.. then i googled it and it showed a chassis dyno.

        ahh right, if you just search 'superflow' there it is... makes me wonder why the numbers are so low now though. very VERY mild tune? haha

        Click here to enlarge Originally Posted by mjmarovi Click here to enlarge
        So, am I looking at this right? 100bhp gain from just the ported heads? I would think this would help spool, but am I wrong in thinking this?
        looks more like 40-60.. at the stock head peak, it's a 40hp difference.. but i assume it'd flatten even more by 7k, so my guess would be MAYBE 60 there.
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        The turbos are making less boost because what most people do not understand is, boost is just a measurement of restriction, boost is the air that isn't getting into and through the motor, you don't touch wastegate settings, put a better flowing head on it, and its going to make less boost but more power because more air is actually being used buy the motor not building up in the intake manifold. A nicely ported cylinder head will become standard for N54 builds in the not so distant future, its cool to see some data for the VAC head.
      1. V8Bait's Avatar
        V8Bait -
        Click here to enlarge Originally Posted by VargasTurboTech Click here to enlarge
        The turbos are making less boost because what most people do not understand is, boost is just a measurement of restriction, boost is the air that isn't getting into and through the motor, you don't touch wastegate settings, put a better flowing head on it, and its going to make less boost but more power because more air is actually being used buy the motor not building up in the intake manifold. A nicely ported cylinder head will become standard for N54 builds in the not so distant future, its cool to see some data for the VAC head.
        Exactly. Boost is a dumb measurement airflow is what matters. Is there any flowbench numbers?
      1. 135pats's Avatar
        135pats -
        Don’t think proper flow bench figures are out, but the gains and curve changes seem sensible and in line with what we know about the stock head design. Whenever I see these types of curves up top…bums me out we can’t rev this thing another 500 RPMs.
      1. jyamona's Avatar
        jyamona -
        So is the turbo from the graphs the same as in the vid? Holset HX40? That's a diesel truck turbo haha, very cheap and popular w/ the DSM crowd. Spooling it by 3500rpm on an engine dyno isn't bad at all, it would spool much faster on the street.
      1. dperf's Avatar
        dperf -
        Some more info from the testing that was done:
        -Testing was done on a Superflow chassis dyno with SAE correction factor in 3rd gear for both before and after head install runs
        -Before dyno graph was pulled to 6750 ish rpms simply because the stock head doesnt make much more power above that
        -Custom single turbo setup using Garrett 3586gtx turbo 21-22 psi in upper rpms
        -93 pump gas very mild tune for road racing reliability
        -peak WHP difference was 553 before vs 603 after
        -Bottom graph line is boost pressure measured in kpa with full spool at 3400-3500 rpms
        -only changes made to tune was changes in wgdc to bring boost to similar for before dyno runs
      1. VargasTurboTech's Avatar
        VargasTurboTech -
        Click here to enlarge Originally Posted by dperf Click here to enlarge
        Some more info from the testing that was done:
        -Testing was done on a Superflow chassis dyno with SAE correction factor in 3rd gear for both before and after head install runs
        -Before dyno graph was pulled to 6750 ish rpms simply because the stock head doesnt make much more power above that
        -Custom single turbo setup using Garrett 3586gtx turbo 21-22 psi in upper rpms
        -93 pump gas very mild tune for road racing reliability
        -peak WHP difference was 553 before vs 603 after
        -Bottom graph line is boost pressure measured in kpa with full spool at 3400-3500 rpms
        -only changes made to tune was changes in wgdc to bring boost to similar for before dyno runs
        This is great info, thanks!
      1. Terry@BMS's Avatar
        Terry@BMS -
        I like what I see here. Almost no bottom end loss and lots of top end gain.
      1. bigdnno98's Avatar
        bigdnno98 -
        Holset turbo on a BMW. OMG people are going to lose their minds LOL. Damn that thing spools fast for a 600HP turbo!!!
      1. bigdnno98's Avatar
        bigdnno98 -
        I wonder if it can rev out past 7200? What kind of springs/retainers are being used on the Stage 3 head?
      1. Mike@VAC's Avatar
        Mike@VAC -
        Everyone understands WHP, WTQ and a power curve.

        This is an independent result that has both us and the client pretty happy :-) I have been off the forums for a bit, but I will post a complete thread soon.

        Details on the head here:
        http://store.vacmotorsports.com/vac-...n54-p1819.aspx

        The Holset video has nothing to do with this dyno sheet :-) This post answers most questions:

        Click here to enlarge Originally Posted by dperf Click here to enlarge
        Some more info from the testing that was done:
        -Testing was done on a Superflow chassis dyno with SAE correction factor in 3rd gear for both before and after head install runs. These dynos run 5-10% lower than Dynojet
        -Before dyno graph was pulled to 6750 ish rpms simply because the stock head doesnt make much more power above that
        -Custom single turbo setup using Garrett 3586gtx turbo 21-22 psi in upper rpms
        -93 pump gas very mild tune for road racing reliability
        -peak WHP difference was 553 before vs 603 after
        -Bottom graph line is boost pressure measured in kpa with full spool at 3400-3500 rpms
        -only changes made to tune was changes in wgdc to bring boost to similar for before dyno runs
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by dperf Click here to enlarge
        Some more info from the testing that was done:
        -Testing was done on a Superflow chassis dyno with SAE correction factor in 3rd gear for both before and after head install runs
        -Before dyno graph was pulled to 6750 ish rpms simply because the stock head doesnt make much more power above that
        -Custom single turbo setup using Garrett 3586gtx turbo 21-22 psi in upper rpms
        -93 pump gas very mild tune for road racing reliability
        -peak WHP difference was 553 before vs 603 after
        -Bottom graph line is boost pressure measured in kpa with full spool at 3400-3500 rpms
        -only changes made to tune was changes in wgdc to bring boost to similar for before dyno runs
        How do you know this?