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stock turbo best shift points n55 auto 1/4mile

Discussion in 'Racing - Kills Discussion' started by slow_henry, Apr 6, 2017.

  1. slow_henry

    slow_henry Private

    Messages:
    37
    Location:
    nj
    Ride:
    335i
    ok i knw they say "oh its auto just put it on drive and go" well not for me, correct me if im wrong but apparently stock turbo falls on its face after 6k or so ive read, so i was trying to get some help from the pros, on a stock turbo n55 auto where have yall find your best shift points obvioulsy to acquire best track times or is it really best to just set it in sport mode and let it do its thing? (thats the one thing i havent tryed)
    currently what ive tryed and worjs best for me;
    traction control off
    brake boost to 2500 on 2nd gear
    shift at 5800
    12;81 @106
     
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  2. doublespaces

    doublespaces Administrator

    Messages:
    6,243
    Location:
    AZ
    Ride:
    2009 E93 335i
    So, you're wanting to make a calibration where it will automatically shift for you at the optimal rpm? Basically, cut off the last 1k?
     
  3. slow_henry

    slow_henry Private

    Messages:
    37
    Location:
    nj
    Ride:
    335i
    not making anything just trying to figure out where it would be optimal to shift manually(paddles) to keep power flowing thru the 1320 as ive read that stock turbo stops making power after 6-6200rpm, im currently trying to figure this out my self at the track with seat time but only get 3 runs limit each time i go and ive been there once this year after upgrades coming from a 13.8 last year bone stock so im just curious as to what people have found to work best for them so i can give it a try next time and see if that improves my times on the 1/4
     
  4. Brodan27

    Brodan27 Lurker

    Messages:
    13
    Location:
    Birmingham
    Leaving it in sport and letting it do it's thing will kill your times. The turbo really does drop off horribly at 6k. You're doing exactly what you need to do to get the best times. Until you upgrade the turbo that is hehe.
     
  5. doublespaces

    doublespaces Administrator

    Messages:
    6,243
    Location:
    AZ
    Ride:
    2009 E93 335i
    Mine is just starting to put out at 4k lol
     
  6. Danksies

    Danksies Corporal

    Messages:
    180
    Location:
    NoVA
    I know this a late post but if you have anything to log with, do a bunch of runs in each gear to see where the boost starts to fall off
     
  7. nitemare

    nitemare Private

    Messages:
    29
    Location:
    Jax, FL
    Without having a dyno chart it's hard to determine but with the stock turbos they always peak hp at about 5500 and you want to shift roughly 200-300 past peak hp to put you in the meat of the tq band for the next higher rpm.

    So you shifting at 5800 is perfect.
     
  8. slow_henry

    slow_henry Private

    Messages:
    37
    Location:
    nj
    Ride:
    335i
    yeah 5800 is where I stayed, with the delay they have it basically shifts at 6k but that gave me the best times at that moment
     
  9. Aaron

    Aaron Sergeant

    Messages:
    424
    Location:
    Colorado
    Ride:
    Silver 2013 335is 6MT
    I'm not sure where anyone here is getting their info from, but I can guarantee you running 1st gear to redline, and most likely 2nd as well, will be beneficial to your track times.

    However, being that you have a stock turbo N55, you should be able to find a comparable dyno chart easily. And of course we know the gears ratios. So do the math and figure out the exact points.
     
  10. slow_henry

    slow_henry Private

    Messages:
    37
    Location:
    nj
    Ride:
    335i
    yeah you are righy I actually rev 2nd gear to 6.5-7k and 5.8 after that
     
  11. dyezak

    dyezak Major

    Messages:
    1,692
    Location:
    Plano TX
    Ride:
    335is
    This isn't rocket surgery. There's plenty a physics calculations behind optimized shift points based on power delivery, weight, and gear ratios. The math is well proven, and even better....there are free calculators on the internet.

    Simply get a good log of your car, run that through Virtual Dyno, go to a shift point calculator program and input your weight, gear ratios, final drive, and the power delivery questions. Press calculate and walk away with the proven answer rooted in physics.

    http://glennmessersmith.com/shiftpt.html
     
  12. dyezak

    dyezak Major

    Messages:
    1,692
    Location:
    Plano TX
    Ride:
    335is
    Spoiler alert.

    My shift points as calculated based on a dynojet readout and my DCT:

    6,350 1-2
    5,850 2-3
    5,700 3-4
    5,650 4-5
    5,650 5-6
     
    Last edited: Mar 21, 2018
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