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When to shift

Discussion in 'Racing and Driving Techniques' started by awptickes, Sep 5, 2008.

  1. awptickes

    awptickes unimpressed by you VIP

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    A common question from many new folks is "When do I shift?"

    There are a few answers that newbies get, and some are wrong, some are right. This is just another method to use.


    First, you'll want to get the gear ratios. Plug the gear ratios into this site:
    http://www.housemanautosport.com/ratio calculator.htm

    [​IMG]

    Then you'll need the diameter of your drive tires. Every tire is different, and wears differently, so you'll need to use your judgement. I plug it into the miata.net tire calculator:
    Tire size calculator

    [​IMG]

    Input the data you just collected, and submit it.

    Now you'll have some numbers, use these to work by. Go to a strip and test them out. There's some experimentation, but it's pretty on-the-money.



    Now, stop asking "When do I shift?".
     

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  2. B16RacerN2NR

    B16RacerN2NR Working Hard VIP

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    IMO, this way is wrong as well. You don't come up with your shift points by looking at your speedometer...

    You get your fucking car on the dyno, see where the power band is, then figure out the shift point that allows you to stay in your power band.
     
  3. wikedeye

    wikedeye Well-Known Member

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  4. YBLEGAL

    YBLEGAL Regular Member w/ Cheese

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    The only problem I see with your method Awptickles, would be with the gear calculator. The average noob says, "I have a B16, so lets see, modify the rev limit value from 8000 to 9000. Sweet that should make me faster".

    Which is why I agree with knowing your powerband.

    And it's not only about the shift on the increase of rpm, but where the motor is after the shift, at the begining of the next gear as well.

    Good attempt.
     
  5. Briansol

    Briansol Admins Admin VIP

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    the IDEAL shift point is a shift that leaves your horsepower peak, and lands you on your torque peak.

    if your car redlines at 8000, but peak hp is at 7000, on paper it doesn't make sense to wind it out.
    BUT
    if shifting at 8k drops you to 4k, and at 7k drops you to 3.5k, odds are that you're more in your torque band at 4k.

    So, you're making more power from 7-8k then you are torque, proportionally from 3.5-4k, thus it's usually logical (on honda motors) to rev it all the way out.


    so, yes, gearing (and even tire size) play into where you land... but it needs to be x-referenced against your peak hp point and peak torque point, and then averaged, and then rationalized, and .... i don't know... too much math.

    just wing it out :D
     
  6. YBLEGAL

    YBLEGAL Regular Member w/ Cheese

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    A good driver can feel the math :p
     
  7. Briansol

    Briansol Admins Admin VIP

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    no, he probably can't. that's ass-dyno territory :D
     
  8. TurboMirage

    TurboMirage YEEAAAHHH VIP

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    i shift when i feel like it, gosh!
     
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  9. phyregod

    phyregod !!YTINASNI

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    No shit. Drive the car. You'll just know when to shift.
     
  10. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    hit the rev limiter count to 10 then shift
     
  11. newb

    newb phresh VIP

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    ^ Fuckin bingo! Thats it!
     
  12. awptickes

    awptickes unimpressed by you VIP

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    lol.
     
  13. Apocalypto

    Apocalypto New Member

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    Exactly.
     
  14. celmore

    celmore New Member

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    ok i took this advice..it seemed to work great! my car is 20 times faster shifting like that i dont know why i didn't do it sooner! Does that work for all gears? I tried it on launch as well!! Other than some awful wheel hop it took off like a rocket!
     
  15. wikedeye

    wikedeye Well-Known Member

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    ^^^I think he was joking.
     
  16. George777

    George777 ^^ Likes Bewbies

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    Neutral drops give you better takoffs...:ph34r:
     
  17. E_SolSi

    E_SolSi Member of the 20 nut club Moderator VIP

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    yes this works for all the gears

    for launch just hold the clutch and gas pedal to the floor when it hits the rev limiter count to 10 and dump the clutch, this will get you your best possible launch (this is the trick the magazines use to get their test results)
    if you find you are getting a lot of wheel spin when launching like this, you need to warm up the tires more... for a FWD car the best way to do this is to put it in reverse, cut the wheel all the way to the right or left, stomp on the throttle using the same rev limiter 10 count that you want to use for the launch, then dump the clutch and count 10 full revolutions of the car, when finished turn the wheel the other way and repeat the process... after this your tires will be properly warmed up and you should get a sweet launch
    if you are still spinning a lot on the launch you may need a wider and softer tire
     
  18. George777

    George777 ^^ Likes Bewbies

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    Good advice, E! I'm gunna try it. I just hope nobody else finds out about this, cuz then everyone will be doing it and I won't have the advantage anymore.
     
  19. 91accordwithwork

    91accordwithwork kid that everyone loves!

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  20. caboose

    caboose USDM to the bone

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    I disagree. Lots of tire spin means that you are doing it right


    If someone wanted to know any of this information, why not just look at your speed as you shift?
     
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