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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Powertrain and Drivetrain Discussions > N54 Turbo Engine / Drivetrain / Exhaust Modifications - 335i > Question about dyno and motor



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      03-21-2013, 01:33 AM   #1
autoart
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Question about dyno and motor

Almost all n54 hp dyno graphs drop or flatin-out after about 5,500 rpms. My question is why? Are the turbo's to small? or is it somthing else? I guess I should be shifting at 5,500 rpms and not letting it go to 6500 rpms when I want to go fast. Thanks.
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      03-21-2013, 07:30 AM   #2
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Yeah, they're too small to keep increasing boost up to redline, or even holding the same as in the midrange. On your shifting...if you shift at 5500 to go faster, you're going to have a bad time.
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      03-21-2013, 08:10 AM   #3
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shift around 6100-6300 rpm if you want to go fast in a 6AT on stock turbos
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      03-21-2013, 09:59 AM   #4
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+1 I shift around 6k
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      03-21-2013, 12:03 PM   #5
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5500 would be too low.

To really understand your shift points you need to dyno your own vehicle then calculate based on gear ratios your highest average HP at what RPM.

Torque is important too. Remember, shifting at peak power is not always the answer, sometimes you want to shift a little after peak power so on the next gear change it drops you into the meat of the powerband.

On average, shifting at 6100-6300 is usually the sweet spot for stock turbos.
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      04-08-2013, 09:54 AM   #6
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Run'm out and run'm hard. Alpina AT shifts at 6800 and for a track flash I would think they probably did a lot of research as to where the best shift point was for the AT. Now that might be a little different for the MT as the gearing is different, but I've always found my 1/4 mile times suffer if I try to short shift. Just my opinion.
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      04-08-2013, 11:31 AM   #7
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With a light tune JB4/ISO + FMIC on 40% E85 I have my shift lights set for 6000, reaction time, mine not the DCT, adds a few hundred RPM to that. Based on my dynos & traps its the best place for me.
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