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Whats your rpm with a 6.2?

Discussion in '1982-Present GM Diesel' started by ryan22re, Jul 11, 2006.

  1. ryan22re

    ryan22re 1/2 ton status

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    What would be a safe/comfortable cruise rpm in the 55-60 MPH range with a 6.2? Is 2600-2800 too hard to run it for a short time (250 miles) for one trip? Will be used around town after that, then regeared with bigger tires.
     
  2. ryan22re

    ryan22re 1/2 ton status

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    Or better yet, what tranny/axle ratio/tire size are you running? I'll figure out the rpms from there :D
     
  3. FWP

    FWP CRS

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    Shiat no. I think Rene went from Canada to Moab and back at that RPM :)
     
  4. JeffHK5

    JeffHK5 1/2 ton status

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    My 84 dump/tow rig has a th400/4.10/29.5 tire and using the speed to rpm calc. that I got here, my rpms are around 2,900 at 65 mph. I was told by a couple guys on a diesel forum I frequent that 3,000 rpm is a good max rpm for any long periods of time. I believe the 6.2 has a 3,250 red-line and overheating is a common problem when there run that hard. I can tell you that my 6.2 has 80K on it and it sounds like it's guts are coming out the tailpipe above 65mph!

    Jeff
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Yup, 2600 rpm on the highway...1200 miles each way. It got on my nerves listening to it, but the truck seemed to like it just fine.

    They're governed to 3600 rpm FWIW.

    Rene
     
  6. colbystephens

    colbystephens 1 ton status GMOTM Winner

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    i thought it didn't have a red-line simply because of the govern which rene mentioned.
     
  7. JeffHK5

    JeffHK5 1/2 ton status

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    I have a speedo but no tach , I was told they have a visual red-line on the tach at 3,200. I have not seen one firsthand so my statement should have had a "?" behind it.

    I have ran my truck at 2,900 (68 mph) for over 3 hours with no problems.

    Jeff
     
  8. DieselDan

    DieselDan 1/2 ton status

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    M1008 (one ton) CUCVs have 4.56 and a 29" tire. The wind up pretty tight at 65mph :crazy: . Pushed for a long distance at high RPM they have a tendency to blow front and/or rear main seals.

    Oh ya, HMMWVs have 3.08 diff plus a geared hub ratio of 1.92 (on a 36-37" tire). "MAXIMUM RECOMENDED SPEED OF 55 MPH" (unless you're being shot at). Thank god they went to the 4L80E for the A2 models :D
     
  9. imiceman44

    imiceman44 1 ton status

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    A friend of mine had a dually crew cab 2wd with 4.56 gears and he lowered it and put lower profile tires, and he used to push 3300 RPM going 600-800 mile trips for a couple of years, he had the tiny tach to confirm the RPM's.
    He ended up blowing the main seal but he fixed that and siwtched to 3.73 gears now.
    :D but the engine still runs strong. It sucked fuel though like you wouldn't believe at 3300 RPM all the time
     

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