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how to calculate rpms?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sapper, Oct 9, 2001.

  1. sapper

    sapper 1/2 ton status GMOTM Winner

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    is there a way to figure out what a highway rpm for a certian speed wpuld be? as in i wanted to run 4.88s with my 700r4 and 37 inch tires going 75 mph?

    <a target="_blank" href=http://coloradoK5.com/gallery/Pauls89K5>http://coloradoK5.com/gallery/Pauls89K5</a>
     
  2. 90blzr

    90blzr 1/2 ton status

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    Rpm's would be 2327 in OD at 75 mph. [​IMG]!

    Check out <a target="_blank" href=http://www.ring-pinion.com>www.ring-pinion.com</a> and click on calculators then go to the one for RPM's[​IMG]
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    MPH X Tranny gear X T-case gear X Rear end ratio X 336 Divided by True tire diameter.

    75 X 0.70 X 1 x 4.88 X 336 / 37= 2326 rpm

    For a non lock-up auto use 355 instead of 336.

    Knowing this formula is handy because you can figure out the R's for any speed in any combination of gears.

    Rene



    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
     
  4. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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  5. sapper

    sapper 1/2 ton status GMOTM Winner

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    thanks everybody now for my next question. will be a good rpm for the power band?

    <a target="_blank" href=http://coloradoK5.com/gallery/Pauls89K5>http://coloradoK5.com/gallery/Pauls89K5</a>
     
  6. K5Jimmy

    K5Jimmy 1/2 ton status

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    .......4lo.com.....shows all combinations on a table....

    Stuck?...Hell no..I still got some gas left..
     

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