05-23-2020, 01:13 PM | #45 | |
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For reference on my 6MT M3, best i could do using the M app was 0-60 in 4.6 but most were 5.0+. Just the nature of a manual in a car with a lot of torque that comes on all at once combined with what I believe is a suspension that has a hard time putting power down. |
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05-26-2020, 06:46 PM | #46 |
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Sorry guys... it is the shift... and it's not the shift.
I've posted about this in another thread here, but it's an artificial delay the DME imposes between shifts on 6MT cars, both N55 and S55. My testing, which you can see in this thread, suggests (with a lot of data), that there is a 2 second delay in waste-gate behaviour started from when you first lift off the gas for the shift. The waste-gate doesn't fully close until this 2 second duration is up, and that slows the rate of boost spooling. Shifting faster actually makes the situation worse, not better, because you'll feel the delay for longer. Shifting quickly at higher RPM can mask the situation because less boost will be lost between your shift, but logs show that it's still there. I've been working with a tuner to eliminate this delay, and it's going really well. I'm basically on the base map from my tuner intended as a starting point for 91 AKI fuel, combined with changes focussing on this waste gate delay and lost boost between shifts. My tuner is still trying to make it more consistent, but it's already about holding boost between 2nd to 3rd shifts about 80% of the time, and 3rd to 4th shifts about 50% of the time. Butt dyne and Draggy data show that the car is way faster once the shift delay is eliminated. I went for a drive to run some errands over the weekend with the Draggy running, and only just now looked at my data. I stated in this thread that my previous best was 5.12s I believe, but without really trying that hard I now have valid draggy from street 0-60 of 4.45, 4.48 and 4.47 (1ft). Screen captures below: Of course, I cannot explain how R&T testers were able to achieve their results, but I actually suspect BMW may have had custom flash for the DME on those cars.
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05-28-2020, 03:54 AM | #47 |
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... fascinating.
Nezil, prior to messing with a tune, what mode did you have the car in when testing 0-60? Full DSC-off, or something else?
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05-28-2020, 06:57 AM | #48 |
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The only way to avoid the delay is to keep the foot on throttle while clutching in to shift. Not good for the clutch, but gets rid of the boost delay.
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05-29-2020, 09:05 PM | #49 | |
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05-31-2020, 11:01 AM | #50 |
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I think I tried everything. In the end Sport+ is usually best if you have a good DSC coding. It allows slip and has aggressive throttle mapping. DSC off would probably be good too; if you have DSC come on, the run will probably be bad, if you spin too much it will be bad also. The important thing is to not be in a mode where DSC cuts in unnecessarily.
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05-31-2020, 11:02 AM | #51 | |
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It really doesn’t feel good though! |
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05-31-2020, 11:06 AM | #52 | |
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05-31-2020, 09:23 PM | #53 | ||
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06-01-2020, 03:39 PM | #54 | |
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That feeling is the bane of the 6mt driving experience with these cars Really looking forward to the final product you guys put together! It would be cool if somehow it could be coded out with BM3 |
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06-02-2020, 08:38 PM | #55 | |
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Shifting faster is quicker overall, but the delay is from the time you come off the gas not from the time you get back on it after the shift. Shifting quicker therefore makes the delayed waste gate behaviour more apparent because it happens for longer after you're back on the gas. It's quicker because you loose less boost if you shift quickly. On the N55 and probably S55, shifting quickly above 6,500 masks the delayed waste gate behaviour because less boost is lost and it rises quickly to the point at which 80% WGDC would be correct anyway. The delayed waste gate behaviour is still there, but it's masked.
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