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What axle gearing

Discussion in '1982-Present GM Diesel' started by Scott39, Feb 5, 2006.

  1. Scott39

    Scott39 1/2 ton status

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    What gears should I go with in my diffs when running a 6.5turbo diesel, and 38"-40" tires?
    And what is the best RPM`s to run the engine down the Highway, and the redline of a 6.5turbo diesel?
    Thanks,
    Scott
     
  2. imiceman44

    imiceman44 1 ton status

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    I think with those tires you want 4.56 gears.
    1900 to 2000RPM is good fuel economy IIRC.
    3600RPM is redline or actually governor speed limit.
    IceMan
     
  3. Scott39

    Scott39 1/2 ton status

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    3600RPM, wow! I`m use to the big semi`s I drive at work, max rpm is around 2100, but they are governed at 1950rpm.
     
  4. imiceman44

    imiceman44 1 ton status

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    Yeah this ia a V8 high revving.
    I have a 6 inline and 1900 is my governed speed.
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    I run 4.56's with 39.5's (no overdrive) and it spins about 2600 rpm on the freeway. It doesn't mind those R's at all, but I do. It's loud and it hurts fuel mileage...

    The 6.2 does respond really well to deep gears, very similar to a small block that way.

    Rene
     

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