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01-19-2014, 10:56 AM | #1 |
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RPM's Shifting
I'm from the old school and would shift when I heard the sound, I liked, coming from the engine. At what rpm's would you take a 2012 135i, w/DCT, to when shifting. Normally I do it around 3-3.5k. Is there an rpm point where you are not gaining any more speed/power?
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01-19-2014, 12:51 PM | #2 | |
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(If you are trying to drag, optimally you will nearly ring it out.) |
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01-20-2014, 05:26 AM | #3 |
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Thank you, that is what I was looking for.
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01-20-2014, 08:11 AM | #5 |
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For maximum acceleration, shifting at 3-3.5k is far too low. You want to be close to the rev limiter (7k) but not at it, suggest around 6.5krpm. However with DCT and such a wide torque band, you can afford to shift a little earlier.
For economy, you'd want to be as low as possible obviously, without the engine struggling too much. So usually <2krpm would suffice to get around town. |
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01-20-2014, 10:21 AM | #6 |
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Checkout a dyno graph. You want to maximize the "horsepower under the curve". I.e. the shaded area below the max horsepower line along the RPM axis. You want to straddle the largest bump in the horsepower curve.
It is important to understand you do NOT want to straddle or maximize torque. If that were true, the fastest N54 on the drag strip would be shifting around 5000rpm, and it would still be much slower than the I6 turbo diesel. For a tuned N54/N55 I think the optimal shift point ends up being somewhere around 6200-6500. Horsepower starts to fall quickly after 6000, but shifting lower puts you at a point on the curve before horsepower peaks. For a stock car, I think it may be slightly higher, maybe more like 6300-6700. Tuning adds slightly more more midrange than it does top end due to huge peak boost numbers that taper faster at high RPM than the stock tune. This adds more horsepower from 5000-5500 than it adds from 6500-7000.
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2009 BMW 135i 6MT Sport, AFE intake, Cobb AP, Apex 18x8.5+9.5, 255/275 PSS
Last edited by Freon; 01-20-2014 at 10:29 AM.. |
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01-20-2014, 01:52 PM | #7 |
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Optimal power range is from 3.3-4.3k for my tune engine. I normally shit at very low 6k before the PSI tapper dives.
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2008 BMW 135i ///MSport Alpine White / Taupe Leatherette Cobb 2+ Aggressive | BMS Intake | ER Charge Pipe + Tial Q | ER FMIC | RR Downpipe | RR Exhaust | RR OCC | KWV1 | Apex ARC-8 245/18/40, 275/18/35 |
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01-20-2014, 03:19 PM | #8 |
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Ok. But when do you shift?
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01-21-2014, 07:04 PM | #10 | |
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