B58 in Supra MKV vs. M340i

Discussion in 'B58 6-Cyl Engine, Exhaust, Drivetrain, Bolt-Ons' started by halfmonkey, Aug 19, 2019.

  1. halfmonkey

    halfmonkey Active Member

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    I think most of us have seen the B58 teardown from the Supra but I'm curious to know how the Supra B58 compares to the one in the M340i. I know Toyota has said in the early press releases that they took the B58 and did their reliability and durability testing on the B58 and made changes to the engine to meet their requirements.

    What I'm trying to figure out is if these changes were only applied to the Supra engine or if BMW implemented them across the board on all of their B58 engines to simplify manufacturing.

    It'd be cool if someone could do an M340i vs Supra MKV B58 teardown/comparison.
     
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  2. justbake

    justbake Well-Known Member

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    If Toyota made changes to the b58, BMW got them as well
     
  3. s219

    s219 Well-Known Member

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    B58/ZF8 combinations in various BMWs and the Supra feel very very similar. After my first drive in the Supra I felt like the powertrain was the biggest aspect of the Supra that felt "BMW", which says a lot considering how much BMW influence is obvious in the vehicle overall. Handling and steering felt unique, but the engine and transmission, and the exhaust note, is very much BMW. I think most BMW drivers will recognize the powertrain right away. It's so similar to what you'll experience in any recent M40i model with the B58/ZF8.

    B38/48/58 development started before Toyota was involved. Whether they asked for rolling changes later on is unknown, but they were definitely not part of the fundamental design and development of the modular engine architecture which spans 3, 4, and 6 cylinders in that family. On top of that, the timing/influence for rolling changes is constrained considering the short amount of time between when Toyota started collaborating on the powertrain with BMW (around 2014) and when BMW's first B48 went into production in 2014 and BMW's first B58 went into production in 2015.

    I personally believe Toyota's involvement in the engine was extremely minimal and I haven't seen any hard evidence, or even hints, that Toyota technology found its way into the B58. We know a lot about Toyota engine design/technology and a lot about BMW engine design/technology, so I think if there were signature Toyota influences it would be obvious. I haven't seen any. The BMW influence is obvious. Toyota influence is a mystery at best.
     
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  4. MA617M

    MA617M Well-Known Member

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    The latest Us spec M340i gets the B58B30O1 as per Z4.
     
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  5. justbake

    justbake Well-Known Member

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    Toyota reliability testing, not technology. No one anywhere has claimed it has Toyota tech, just that Toyota made reliability changes
     
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  6. OP
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    halfmonkey

    halfmonkey Active Member

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    So it seems that the B58 in the Z4 is different from the one in the Supra. On page 375 of the Supra owner's manual, it refers to the engine as B58B30C.

    Does anybody know what constitutes the difference between the B58B30O1 and the B58B30C?
     
  7. justbake

    justbake Well-Known Member

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    The B58C is officially denoted as the B58B30M1 and most notably has the exhaust manifold integrated into the head where as the O1 has a traditional exhaust manifold
     
  8. s219

    s219 Well-Known Member

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    There are three main variants of the B58 and a total of six versions if you split hairs. Google "bmw b58 family" and lots of information will turn up. One common theme to all of them is that the power rating is way underrated. I have a "355HP" B58B30M0 in my X3 M40i which dynos around 440HP (crank).
     
  9. MA617M

    MA617M Well-Known Member

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    Yes, as mentioned

    B58C = B58B30M1
    B58D = B58B30O1
     
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  10. Cjp78

    Cjp78 New Member

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    I work at BMW manufacturing In Spartanburg SC, we build the X series. The B58 we install in X5 is the B58c also.
    Personally I don't believe the B58 in the Supra is any different than the same engine code found in some BMWs. It's tunning is just done by Toyota instead of BMW.

    To my understanding Toyota and BMW started working together around the time of early development on the B58. Toyota got to give some input on the B58...that's my understanding, could be wrong
     
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  11. Zupraman

    Zupraman Well-Known Member

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    After some time has passed, do you still feel this way? Is the head in the x5 the same with the integrated exhaust manifold, and the rods/pistons are the same as well?
     

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