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what gear ratio should i run?

Discussion in '1982-Present GM Diesel' started by jp0863, Dec 13, 2005.

  1. jp0863

    jp0863 1/2 ton status Premium Member

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    6.2, turbo 400.... i'm running 35's now with 4.10's. looking to run 37's when the 35's wear out. what gear ratio should i be running now and what should i switch to when i get 37's?... not too sure since i have no tach and no overdrive.
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    It kinda depends on how you use the truck. I'm a firm believer in gearing as low as is practical with a 6.2...it keeps them from feeling like complete dogs.

    Currently at 65 mph your 6.2 is spinning at about 2550 rpm. It should have plenty of power geared the way it is, but won't return the optimal fuel economy. 37's will drop the rpms to 2420 at the same speed and will likely increase your fuel mileage by about 1 mpg.

    My truck runs in the same rpm range (4.56's and 39.5's, 2520 rpm @65) and I like it for around town. On the freeway it's loud and you'll almost never find me in the fast lane. My mileage is about 16.5 steady freeway though.

    The next gearing option for you is 4.56 and IMO this would make the freeway misery for you. Even with the 37's it'll be turning at 2700 rpm.

    Rene
     
  3. jp0863

    jp0863 1/2 ton status Premium Member

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    i was kinda thinking along the same lines. i mainly use it for offroad, but ordered a soft top and am going to start driving it to work once in awhile. it does seem to rev sorta high on the fwy, but without a tach i cant tell. was thinking maybe it just sounds like it's reving high. the mileage is better than my 04' f-350 diesel which is surprising to me. thanks a bunch for the info.
     
  4. imiceman44

    imiceman44 1 ton status

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    I agree keep the same gears and slap on your 37" tires you'll like the increase in mileage and drop in noise.
     

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