shift point calculator for wrx and sti

Discussion in 'Modifications & DIY how-to' started by miloman, Jun 15, 2005.

  1. miloman

    miloman Retired Admin

    i built one in excel a while back and forgot to post it up on the site. here's how it works:

    * open the excel file
    * on the 'enter dyno data' sheet, enter your torque values at the given rpm's (ive chosen 500 rpm increments from 1500 to 7000)
    * the 'dyno plot' sheet will show your dyno plot generated from the selected sample points. check if this looks about right.
    * the 'shift points' sheet will give you your shift points... u will notice that in higher gears, the torque curve will get longer but lower in value... horizontal axis represents road speed in mph... the speed at which 2 torque curves cross is your shift point

    there are some flaws in it but i dont think i can make it any better unless i
    * take a lot more sample points
    * have dyno plots for the different gears

    let me know what y'all think

    UPDATE: added the STi calculator also... please look at the max speed in each gear and let me know if it looks reasonable... i might have to recalculate something
     

    Attached Files:

    Last edited: Jun 28, 2005
  2. miloman

    miloman Retired Admin

    heres an example...

    this is the output for my car...

    1-2 @ 35 mph(redline)
    2-3 @ 60 mph
    3-4 @ 85 mph
    4-5 @ 115 mph
     

    Attached Files:

  3. moose

    moose Infina Mooooooose!

    The spreadsheet comes up blank here...

    Can you plot it by RPM as well?
     
  4. miloman

    miloman Retired Admin

    the whole spread sheet is blank?

    i didnt plot it by rpm for a couple reasons:
    * u will run through the rpm in all gears so the x axis would be confusing
    * i think road speed gives u a better idea what ur ideal gear is... if u wanna remember rpms, u will have to remember the upshift rpm and downshift rpm also to determine which gear is best... if u remember speed, it makes it easier in my opinion
    * if u really wanna read rpms, u can gauge it approximately by looking at the sampling points in the plot... the sampling points are spaced 500 rpm apart starting from 1500 to 7000
     
  5. miloman

    miloman Retired Admin

    i uploaded it again... try downloading now
     
  6. rolling_trip

    rolling_trip Active Member

    make me one for the sti, college boy :fruit:
     
  7. Weapon

    Weapon 90lbs of dynamite Supporting Member

    hehe..mine is
    1st gear shift at redline
    2nd gear shift at redline
    3rd gear shift at redline
    4th gear shift at redline
     
  8. miloman

    miloman Retired Admin

    i'll make it... i just need to know one thing about ur car...

    drive around in 6th gear... pick a certain rpm and tell me what EXACT speed u hit at that EXACT rpm
     
  9. rolling_trip

    rolling_trip Active Member

    with my cruise on 80 i am dead on 3100rpm
     
  10. Suby1128

    Suby1128 Member

    1st - 2nd: approx. 32 mph (6500 rpm)
    2nd - 3rd: approx. 55 mph (6000 rpm)
    3rd - 4th: approx. 80 mph (6200 rpm)
    4th - 5tg: approx. 110 mph (6000 rpm)

    My only problem was that I didn't have data points from until 2500 rpm or after 6000 rpm, so mine may be a little off. Do those numbers sound feasible?
    Craig
     
  11. miloman

    miloman Retired Admin

    sounds about right
     
  12. rolling_trip

    rolling_trip Active Member

    status for us sti owners?
     
  13. miloman

    miloman Retired Admin

    sorry... i didnt get time... will have this ready before u go drag racing tomorrow :)
     
  14. sol drums

    sol drums Active Member

    question?

    is it better to shift at redline or before?

    -drums
     
  15. Suby1128

    Suby1128 Member

    it depends on your graph, mine is less because my car doesn't hold boost well past 6000 rpm
    Craig
     
  16. rolling_trip

    rolling_trip Active Member

    u still have urlast dyno sheet? that will be a good starting point. its hard to say with ur turbo, i will prob strech out 6000-6500rpm the 1-2, 2-3, and shift out at 5800-6000rpm the rest
     
  17. sol drums

    sol drums Active Member

    i guess if we get enough runs i can try both and see what's faster. i still have my dyno sheet but i'm prolly putting down better numbers now since scott tuned it.

    -drums
     
  18. jt money

    jt money 350hp mmm mmm Good! Supporting Member


    thats how i drive too. :keke:
     
  19. miloman

    miloman Retired Admin

    sti calculator added... please check to see if the max speed in each gear seems reasonable... otherwise i have an error
     
  20. rolling_trip

    rolling_trip Active Member

    u the man!
     
  21. miloman

    miloman Retired Admin

    :wiggle:
     
  22. miloman

    miloman Retired Admin

    STi owners... i have modified the STi calculator since i found that rollin trip does not know how to read his RPMs :keke: jk buddy...
     
  23. rolling_trip

    rolling_trip Active Member

    the gloves are off now, bring it on college boy, wait a minute where did i put my F%$#@ keys, not again!
     
  24. GTscoob

    GTscoob Black is Beautiful

    I havent played around with it yet since I havent dynoed but can you change gear ratios around in it?

    When I get Ecutekked I want to see what I should be doing with my 4.44 box:naughty:
     
  25. miloman

    miloman Retired Admin

    yes u should be able to
     
  26. Genya

    Genya No Longer Up At Odd Hours

    Awesome tool once again!

    1st-Redline
    2nd-6500
    3rd-6500
    4th-6500
    5th-whatever.

    Cool time to set the shift point light.
     
  27. miloman

    miloman Retired Admin

    thanks... im curious about accuracy though... i think i have the RPM to speed conversions pretty close for WRXs but i don't have reliable input from a certain STi owner ;)

    also the shift points are based off dyno plots... dunno if the curve is the same in different gears
     
  28. miloman

    miloman Retired Admin

    bump it up
     
  29. Deke

    Deke Active Member

    That's pretty cool man. I had to use a random sample dyno, but first gear torque curve and second gear torque curve don't cross.
     
  30. Kokopelli

    Kokopelli Active Member

  31. miloman

    miloman Retired Admin

    then go to redline
     
  32. Alex

    Alex Community Founder Staff Member

    Milo and I were discussing this last night actually. For those confused, the basic calculation includes 3 variables: torque, wheel width (in ft) as well as final drive ratio.
     

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