Cummins ISX15 vs Detroit DD15??

Discussion in 'Trucks [ Eighteen Wheelers ]' started by planafreighters, Aug 15, 2015.

  1. planafreighters

    planafreighters Light Load Member

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    I have yet to talk to a mechanic about this so I figured until then I will start here. I have heard pros and cons about both but I myself have only had experience with the ISX15. It was in a T660 and had to be rebuilt at 330,000 miles because the valve guides went crap and began creating a ton of serious issues. My main concerns are pulling power (Uphill) and longevity. What are your thoughts??
     
    Oldironfan Thanks this.
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  3. Cranky Yankee

    Cranky Yankee Cranky old ######

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    recent vintage i have only driven paccar and DD15
    the DD15 saw the shop much less
     
    free2fly973 Thanks this.
  4. planafreighters

    planafreighters Light Load Member

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    How did it pull in the hills??
     
  5. Cranky Yankee

    Cranky Yankee Cranky old ######

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    well pullin wy is ok
    this one is an auto DD12 never put it in manual
    last one was 13 speed
    I see no difference both were goverened at 75
    the paccar was goverened at 64 so had its balls cut off
     
    paul_4lp Thanks this.
  6. planafreighters

    planafreighters Light Load Member

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    Yeah the Kenworth T680 I drive now has the Paccar which seems to do alright except for the fact that I wish it would pull hills a bit better. This is mainly due to the company's choice to equip it with 2.64 rear ends!! Great for fuel conservation, sucky for trying to pull heavy uphill.
     
  7. tech10171968

    tech10171968 Medium Load Member

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    The company I used to drive for had mostly Cornbinders with the ISX, but the balls were cut off (governed at around 62). We'd even get passed by wheelchairs on flat ground but, when a big hill would come up, it was a completely different story: they still weren't speed demons but they'd pull the hell of of a hill. We'd even pass some suddenly surprised O/O rigs. Our International 9400s w/ the redhead Cummins were monsters on a steep grade but sheep on flat land. Don't know if it was the engine itself or the rear ends but that was my experience.
     
  8. KeithT1967

    KeithT1967 Road Train Member

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    Sometimes I wonder if people are aware that there are many different specs available on the same motor family.

    DD 15's were available with up to 560hp and 2050ftlbs.
    I think they are currently avail to 515/1850 but it may be only 505.

    Which ISX? There have only been at least 5 basic versions. CM570, 870, 871, 2250, and 2350. Up to 600hp from the factory.

    I havent driven a big DD15 but put 178k on a 455. Not too shaby pulling reefer 48 state. Dead reliable for sure.

    Done a lot of miles driving a 600hp CM870 ISX. That thing would pull a freight train up a cliff if it could get traction. Engine brake like the hand of god.

    Currently in a CM 871 ISX set at 475/1750. Definately no slouch with a 13 and 3.58 rears backing it up.
     
  9. planafreighters

    planafreighters Light Load Member

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    Keith you are right. It just seems like most of these companies go for the weaker tunes and taller rear ends for fuel conservation. Whichever manufacturer I end up going with, I will try and get the most torque rated version I can get without stepping all the way up to the 2000+ ft lb beast as well as a 3.30 to 3.50 rear end ratio for 48 state driving.
     
  10. mhyn

    mhyn Road Train Member

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    dd15 or dd15tc max has 505 hp and 1750 ft lb now. there is no way to pump it to 565hp because of 1-box aftertreatment . cm2350 500 hp engine has 2050ft lb torq. if you pull heavy loads buy Cummins factory 500hp + cm2250 or 2350 engine.
     
  11. Hurst

    Hurst Registered Member

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    A couple weeks ago I spent a little over a week in a 2009 Cascadia with DD15. Supposed to be 450hp, but it had some things done to the emissions that we cant talk about here and it felt much stronger.

    I was pulling step deck with 60 - 80k gross loads. It only had a 10 spd with 3.42 rear gears,.. but it pulled the hills on i68 in md and i80 in PA pretty decently. I would put it on par with a 475hp/1850 trq acert C15. Not quite as smooth down low,.. but pulled respectably.

    EDIT:

    I want to add also that the truck saw 6 - 6.8 mpg while I was monitoring it. Much better than any C15 or Cummins I ever drove.

    Not sure I would ever buy one. The motor had been recently rebuilt after losing oil pressure and the motor seized up. Odometer only showed 570k when I was in it. My C15 was at almost 1.3 before I had to have it rebuilt.

    Hurst
     
    Last edited: Aug 16, 2015
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