+ Reply to Thread
Results 1 to 3 of 3

Thread: Optimal Shift Point Calculator

  1. #1
    Offical SM Expert: Suspension & Vehicle Dynamics
    supraguru05's Avatar
    Join Date
    Dec 2005
    Location
    louisville ky
    Posts
    734

    Default Optimal Shift Point Calculator

    This excel sheet was created by me and my friends to allow for the proper determination of shift points. I will be posting a report of how the calculations are made in the coming days. In order to use the sheet you must input your torque curve. You have 15 cells to use you can use some or all of them and change the RPMs as you see fit. You much also input tire diameter, tranmission ratios and final drive ratio. Simply click the large run button and the shift points will automatically update. Macros will need to be enabled.
    Last edited by supraguru05; December 2nd, 2010 at 01:15 PM.
    ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
    1989 toyota supra white package DD
    1989 toyota supra NASA TTC track car
    thanks to
    Supramania.com, No Lift Racing, Epic Motorsports
    Visit My Sponsors At
    NOLIFTRACING.com, brewerheatingandair.com

  2. #2

    Default Re: Optimal Shift Point Calculator

    That is a really neat tool but I think theres a flaw in it. I did some calculations by hand based on the numbers in your sheet when you first open it up. It tells you to do a 1-2 shift at 5490; at 5500 in 1st your car is making 225 at the ENGINE, which would end up at 3308 in 2nd making about 315, also at the engine. If we multiply those numbers by the gear ratio, ignoring diff/wheel size etc. since they are constant across all gears, I got 731.25 in 1st at 5500, 625.6 in 2nd at 3000 and 606.05 at 3500, which is between where it tells you to shift. Youre making more at the engine but less at the wheels.

    It tells you to make the 3-4 shift at 4988 RPM, which at 5000 with a 1.31 ratio for 3th we're making 340.6tq, a number that is never reached in 4th at any RPM (max tq is 320 at 3000 since 4th is 1:1). Similarly the 4-5 shift is supposed to be made at 5070 and at 5000 RPM we're making 260 tq, which is never reached in 5th. Max for 5th with .735 ratio is 235.2 at 3000.

    Someone double check my math.

  3. #3
    Offical SM Expert: Suspension & Vehicle Dynamics
    supraguru05's Avatar
    Join Date
    Dec 2005
    Location
    louisville ky
    Posts
    734

    Default Re: Optimal Shift Point Calculator

    updated sheet
    ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
    1989 toyota supra white package DD
    1989 toyota supra NASA TTC track car
    thanks to
    Supramania.com, No Lift Racing, Epic Motorsports
    Visit My Sponsors At
    NOLIFTRACING.com, brewerheatingandair.com

+ Reply to Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Links monetized by VigLink