detroit diesel 12.7 vs 14L

Discussion in 'Ask An Owner Operator' started by vader696, Jan 18, 2011.

  1. SpankingGT

    SpankingGT Light Load Member

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    I have 04-columbia 470-14;-13 spd w/2.93 rear end and easily attain 7 on 40k and heavier loads (75-78k). Unless your rear end ratio is 3.70 with 10 spd, you should atleast be seeing 6.0 avg. I run fast as well @70mph Im barely touching 1500rpms. Have your truck checked out.
     
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  3. MedicineMan

    MedicineMan Road Train Member

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    Woodville, TX
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    good for you



    i running 3.50's, 10 speed on low 22.5's

    its not set up for the west coast running i do but its what i could buy at tge time. its a very typical co. spec.

    and i can get 6 if im trying. but compare that with the 500hp 12.7 classic i was getting 7 out of and i dont consider it very good. also the 14 fall on its face in the hills.and the only thing wrong with my truck is that its due for an overhead
     
  4. 25(2)+2

    25(2)+2 Trucker Forum STAFF Staff Member

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    the road less travelled
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    The one I'm drivng is an 08 with 455 HP and 10 speed OD with 3.42 ratio and 22.5 low pros. It's not set up for mountains, but clearing up a rough idle and surging problem under load with a new flash has made it much better pulling the hills as well.
     
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  5. Trouble65

    Trouble65 Medium Load Member

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    Ontario Canada
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    My 98 500hp 12.7 ltr engines outperform my 05 14ltr on every catagory.
     
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  6. Krooser

    Krooser Road Train Member

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    Good reason to keep the old stuff running...
     
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  7. x#1

    x#1 Road Train Member

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    Cherokee County, Alabama
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    Although I am not an O/O,this is an interesting thread.I drive a 12.7,430/470,10 over@3.73 rears,turning 2250,11R/22.5, and have never seen 7. 6 is obtainable IF the loads are light.4.7-5/5.3 is the actual mpg.that is just plain lousy.I do run heavy and hard/fast.
    So.Can you advice me regarding the flash that was put into the ecm? We haul lots of scrap metal and need the pulling power that you type about.I am sure the mpg's would go up if the truck was set up as it should be.The engine is set as it should be from the factory,no restrictions, although i now suspect that there are different parameters that could be put into the ecm.Comments please.
    THANK YOU in advance.

    Oh yeah.2003 century w/2002 12.7.I also have algae in the fuel system it seems.Any suggestions regarding that? Was told that alcohol,one large bottle per tank,would clear that up.True? How about an overhead/rack? That should prove beneficial too don't you think?
     
  8. MedicineMan

    MedicineMan Road Train Member

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    if u run faat the 3.63's are killing you. and if you do a fair bit of stoping and starting the ten speed is hurting.

    run the overhead, free flowing muffler have the charge air cooler checked for leaks.

    fill the tanks with red offroad fuel. that will kill the algea. it will also cost ya $30k if u get caught driving it. lol
     
  9. MedicineMan

    MedicineMan Road Train Member

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    Woodville, TX
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    you wont ever see 7 in a short hail or city truck. if your shifting your lowering your fuel mileage
     
  10. tate2133

    tate2133 Bobtail Member

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    Jul 20, 2010
    El Dorado Springs, MO
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    What is the avg MPG
     
  11. tate2133

    tate2133 Bobtail Member

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    Jul 20, 2010
    El Dorado Springs, MO
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    Ive got 12.7 avg 5.75, MBE 5.25
     
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