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RPM's @ MPH w/tranny & gears.....

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BLzr4x4ngkid, Oct 26, 2000.

  1. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    RPM\'s @ MPH w/tranny & gears.....

    What would the RPM's be with the following set up??

    700R4 w/4.11 and 4.56 gears @ 40, 60, 70, 75mph(roughly)

    TH400/TH350 w/ same gearing and speed.

    If someone could give me the specs as closely as possible I'd appreciate it. I am just kind of curious what the RPM's would be at those speeds with those set-ups. Any kind of reply is welcome.

    "Don't hit me with them negative waves so early in the morning." Odd Ball--Kelly's Hereos
     
  2. Emmettology 101

    Emmettology 101 3/4 ton status

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    Re: RPM\'s @ MPH w/tranny & gears.....

    Need to know what tires you are running.

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Re: RPM\'s @ MPH w/tranny & gears.....

    Hmmmmmmmmm.......fun with math![​IMG]
    Heres the formula: MPH x AR x TC x TR x 336 / Tire Diameter (true diameter)

    MPH-speed in Miles per hour
    AR-Axle ratio
    TC-Transfer Case (low range or high range ratio)
    TR-Tranny gear (overdrive ratio)

    So a 700R4 W/4.11's at 50MPH in OD with 32" tires would be 1510 RPM.

    50(MPH) x 4.11 x 1 (T-case high range) x .70 (OD 700R4)x 336=48333.6
    48333.6 / 32 (true tire diameter) = 1510.42 RPM

    This is just a quick example, for standard transmission and auto's with lock-up convertors multiply by 336. For non lock-up auto trannys multiply by 355.

    Same example with a TH350:
    50 x 4.11 x 1 x 1 x 355 / 32 = 2279 Rpm.

    Hope that helps.

    Rene

    [​IMG]
     
  4. 89Jimmy

    89Jimmy 1/2 ton status

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  5. Emmettology 101

    Emmettology 101 3/4 ton status

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    Re: RPM\'s @ MPH w/tranny & gears.....

    Thats what I was going to say next! LOL

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     
  6. BLzr4x4ngkid

    BLzr4x4ngkid 1/2 ton status

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    Re: RPM\'s @ MPH w/tranny & gears.....

    I'd be running 35's. Sorry.

    "Don't hit me with them negative waves so early in the morning." Odd Ball--Kelly's Hereos
     
  7. Emmettology 101

    Emmettology 101 3/4 ton status

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    Re: RPM\'s @ MPH w/tranny & gears.....

    4.11 gears, 35" tires and a 700r4 =
    1381 @ 50 1657 @ 60 1933 @ 70 all in OD
    2026 @ 50 2431 @ 60 2836 @ 70 all in D (also comparable to a TH350 and TH400)

    Mike [​IMG]
    See <font color=green>EMMETT</font color=green> -&gt; http://emmett.coloradok5.com
     

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