10-06-2020, 07:49 PM | #23 | |
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10-06-2020, 08:43 PM | #25 |
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No they are not flex joints, they are cats.
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10-06-2020, 08:52 PM | #26 |
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10-06-2020, 09:58 PM | #27 |
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Sorry equal-length guys, in the pic right behind the skid plate is a 18-24in section running sideways. This makes the length unequal. The short side runs rearward immediately, but the long side routes around the gearbox/trans (?) in the middle.
This is yet another thing on the new Gs that make no sense...like the big honker, and locked ECUs.
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10-07-2020, 05:08 AM | #28 | |
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Based on this, I am one to believe the G8X will sound much better than the F8X.
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10-07-2020, 07:28 AM | #29 |
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Packaging for AWD
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10-07-2020, 07:55 AM | #31 | |
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10-07-2020, 10:33 AM | #32 | |
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10-07-2020, 12:05 PM | #33 |
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There could be more than one answer, packaging aspects could have been the trigger and when the idea was out there why not spend the effort to achieve EL when you’re at it. Or vice versa.
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10-07-2020, 12:26 PM | #34 |
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I don't speak German, so don't know precisely what was said about the exhaust lengths. But could be that the engineer is confirming exhaust lengths to achieve a particular sound, not that they are equal.
The sound of the car in the video sounds very unequal exhaust phasing to me. Then there the 'a picture is worth a thousand words' . Take a look at how much deviation there is in the two pipe runs in the OP, and then look at this pic of the turbo layout on the S58. Notice how they stagger horizontally to get them as close to each other as they can. The outlets are far closer than they are on an S55. Look at how far forward the rear turbo is. Nothing equal length about that setup in my opinion. The sound in the video shouts unequal. |
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10-07-2020, 01:15 PM | #35 |
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10-07-2020, 01:17 PM | #36 | |
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When the Youtuber comments that the exhaust sounds very "clean", the BMW ///M employee clearly states that they made the two exhaust pipes the same effective lengths so that the exhaust pulses alternate nicely for it to sound like a more typical inline-6.
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10-07-2020, 02:48 PM | #37 | |
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You can clearly see from the turbine positions on the S58 pic I attached, that there isn't much difference in length to address to achieve an equal length system. The airborne pic shows a big diversion by crossing one pipe over the gearbox, adding much more than the turbo spacing difference. All the data given in this thread cannot all be true. |
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10-07-2020, 03:18 PM | #38 | |
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10-07-2020, 05:21 PM | #39 | |
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10-07-2020, 05:33 PM | #40 | ||
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10-07-2020, 05:56 PM | #41 |
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Very curious to see how they route the exhaust (driver vs passenger turbo) and if they truly flipped it on the G8x like they did on the X3M vs the S55., or if they kept the rear bank turbos routed to the passenger side ("short" side) because they are on slightly different platforms.
If they kept the S55 set-up, I can see why they did they piping. But if they kept the S58 X3M set-up, they may have been doing something unusual but effectively equal-length but in a different cylinder pulse spacing method. The videos posted sound decent over the S55 thus far, even compared to my CS when it was stock and not customer equal-lengthed. |
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10-28-2020, 02:27 PM | #42 |
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I'm no engineer, but learned as much about the science of tuning as I could when I was younger and have always been into physics and chem and spent a few years 15 years ago building some pretty wild cars...
I mean it seems like common sense, maybe I'm wrong but wouldn't you really need equal back pressure for bank 1 and bank 2, as cam phasing for peak HP would vary slightly on back pressure? And as far as I know VANOS doesn't allow different phasing or varied lift/duration for each individual cylinder? Maybe they engineered it to be as close to equal as possible and use other means, bends, pipe size variations to keep exhaust velocity and resistance as close to equal as possible? Or is the difference in back pressure not big enough to cause a difference in appropriate cam timing/lift/duration for bank 1 and 2?
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10-28-2020, 03:23 PM | #43 | |
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