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    • B58 beats N55B30T0? BMW F22 M240i automatic faster than BMW F87 M2 DCT

      This is incredible. The M240i beating the BMW M2 in acceleration? The N55B30T0 motor we know is basically an N55/S55 hybrid and it is restricted to ensure the M4 is not threatened. So why is BMW allowing the M240i to threaten the M2?


      The B58 is certainly a stout engine and it is a new architecture compared to the N55. It responds very well to modifications although it is fuel capped. Still, how is the B58 beating the N55B30T0?

      For one, the B58 is underrated and has a flatter torque curve. The M2 actually has similar power to the M240i. Forget the BMW crank figures. The B58 power curve also increases toward redline whereas the N55B30T0 torque curve drops off a cliff.

      It shows in how this comparison plays out. The M2 has the advantage down low partially due to its low rev torque peak but also due to the shift speed advantage offered by the DCT transmission.

      The M2 gets to 60 mph quicker but past 70 mph or so miles per hour the B58 is the one pulling harder. The difference becomes startling as the M240i pulls to 260 kph (161 mph) while the M2 is trailing badly.

      What do you even say to this? The M2 is tuned how the M240i should be tuned and the M240i has the sort of curve the M motor should. What is BMW doing? Do they even know?


      This article was originally published in forum thread: B58 beats N55B30T0? BMW F22 M240i automatic faster than BMW F87 M2 DCT started by Sticky View original post
      Comments 34 Comments
      1. richpike's Avatar
        richpike -
        Wow. Does the B58 use a different intercooler type? That looks like heat soak.

        -Rich
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by richpike Click here to enlarge
        Wow. Does the B58 use a different intercooler type? That looks like heat soak.

        -Rich
        From one pull? I don't think it's heat soak that quickly. The B58 just rips it up top.
      1. ///MPOSTER's Avatar
        ///MPOSTER -
        Haven't seen you around the forums @richpike . Hope you are doing well in CO.
        @Sticky the noticeable differences would be the intake tract route being longer on the M2 and the 240i having a hot side intake placement which shortens it . Almost like a TFT or whatever and then it looks like that freed up room to have a shorter charge pipe to the intake manifold. I can't really tell from just the top down engine shot of the 240i how the chargepipe comes from the passenger side. Different intercooler?
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by ///MPOSTER Click here to enlarge
        Haven't seen you around the forums @richpike . Hope you are doing well in CO.
        @Sticky the noticeable differences would be the intake tract route being longer on the M2 and the 240i having a hot side intake placement which shortens it . Almost like a TFT or whatever and then it looks like that freed up room to have a shorter charge pipe to the intake manifold. I can't really tell from just the top down engine shot of the 240i how the chargepipe comes from the passenger side. Different intercooler?
        Don't quote me but I remember reading that the B58 intercooler design was different.

        Are we really attributing that kind of pull to the intercooler though? In the higher gears I think what we see in the curve plays out. Keep in mind the M2 is not dropping as far down into the rev range meaning it's not sitting near its torque peak.

        I just think the N55B30T0 top end is weak by design.
      1. richpike's Avatar
        richpike -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        From one pull? I don't think it's heat soak that quickly. The B58 just rips it up top.
        It's a full 30second pull. Not the same, but I'd see IAT spike significantly on my 335 going through just three gears.

        -Rich
      1. richpike's Avatar
        richpike -
        Click here to enlarge Originally Posted by ///MPOSTER Click here to enlarge
        Haven't seen you around the forums @richpike . Hope you are doing well in CO.
        @Sticky the noticeable differences would be the intake tract route being longer on the M2 and the 240i having a hot side intake placement which shortens it . Almost like a TFT or whatever and then it looks like that freed up room to have a shorter charge pipe to the intake manifold. I can't really tell from just the top down engine shot of the 240i how the chargepipe comes from the passenger side. Different intercooler?
        Thanks - things are going well. Hope you are doing well too!

        -Rich
      1. richpike's Avatar
        richpike -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge

        I just think the N55B30T0 top end is weak by design.
        Definitely agree, but it seems like there may be something else in play too. I'll have to look at the gearing too.

        -Rich
      1. Ando@BMS's Avatar
        Ando@BMS -
        I just don't know why they didn't put B58 in the M2 and leave m240i with N55.
      1. Sw4y1313's Avatar
        Sw4y1313 -
        The B58 has a water to air Intercooler setup that has the core built into the intake manifold. It's got a really short charge system that I'm really fond of. I'm sure with a large volume system and high quality dual pass heat exchanger it could take a ton of beating without heatsoak.
      1. bigdnno98's Avatar
        bigdnno98 -
        This is very interesting as one of these will be my next car. Still can't decide and this only makes it worse.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Ando@BMS Click here to enlarge
        I just don't know why they didn't put B58 in the M2 and leave m240i with N55.
        The answer is the B58 will produced longer as will the M240i. The M2 is recycling certain parts.

        The M240i might be the better buy for those who don't care as much about tracking but want to mod for power.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by Sw4y1313 Click here to enlarge
        It's got a really short charge system that I'm really fond of. I'm sure with a large volume system and high quality dual pass heat exchanger it could take a ton of beating without heatsoak.
        So essentially update it sort of like an S55 system?
      1. inlineS54B32's Avatar
        inlineS54B32 -
        WOW!

        The M2 gets to 60 mph quicker but past 70 mph or so miles per hour the B58 is the one pulling harder. The difference becomes startling as the M240i pulls to 260 kph (161 mph) while the M2 is trailing badly.

        Yeah, that motor is extremely anemic relative to the N55B30 at the higher end of the rev range. It's almost not even comparable. Call me shocked, then look at the dyno - and it makes sense. As you said, falls off like a cliff vs. "normal" curve.
      1. 135idct's Avatar
        135idct -
        the m240i is faster becuz the ZF trans, i drove n55 m2 dct and n55 235i after 115 mph or high speeds the ZF 8At keep pulling hard. becuz the trans not the engine!
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by inlineS54B32 Click here to enlarge
        Yeah, that motor is extremely anemic relative to the N55B30 at the higher end of the rev range. It's almost not even comparable. Call me shocked, then look at the dyno - and it makes sense. As you said, falls off like a cliff vs. "normal" curve.
        Whenever I mention the N55 design falls off a cliff people tell me it's actually a nice torque curve... lol.
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        the m240i is faster becuz the ZF trans, i drove n55 m2 dct and n55 235i after 115 mph or high speeds the ZF 8At keep pulling hard. becuz the trans not the engine!
        No.
      1. 135idct's Avatar
        135idct -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        No.
        look at any acceleration vid of the M2 and M235i from 124mph to 150mph, the m235i much faster!
        by the way i tested both cars the m235i much faster at high speeds. you can see youtube acceleration vids and count the time!
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        look at any acceleration vid of the M2 and M235i from 124mph to 150mph, the m235i much faster!
        You think it's faster at higher speeds due to gear shifts? Heh. A DCT has lower drivetrain losses as well not to mention quicker $#@!s.

        The M235i wins because of its top end pull.

        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        by the way i tested both cars the m235i much faster at high speeds. you can see youtube acceleration vids and count the time!
        I'm not debating this. I'm just not saying it's the ZF auto that makes that possible. I'm saying it is the motor.
      1. 135idct's Avatar
        135idct -
        Click here to enlarge Originally Posted by Sticky Click here to enlarge
        You think it's faster at higher speeds due to gear shifts? Heh. A DCT has lower drivetrain losses as well not to mention quicker $#@!s.

        The M235i wins because of its top end pull.



        I'm not debating this. I'm just not saying it's the ZF auto that makes that possible. I'm saying it is the motor.
        the ZF 8At and the drag coefficient of the m235i much better.

        by the way the drag coefficient of the m2 is the same as the m135i !!
      1. Sticky's Avatar
        Sticky -
        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        the ZF 8At and the drag coefficient of the m235i much better.
        Once again, it's not the trans. Especially at higher speeds where there is less shifting and more time spent in gear. The auto also has slightly higher drivetrain losses. This same dual clutch in the M4 and other M cars has no top end issues.

        Click here to enlarge Originally Posted by 135idct Click here to enlarge
        by the way the drag coefficient of the m2 is the same as the m135i !!
        Ok?