Detroit 12.7 turbo upgrade

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Idaho379, May 28, 2022.

  1. benjamin260_6

    benjamin260_6 Medium Load Member

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    Aug 8, 2012
    Ontario, Canada
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    Don't plug your wastegate. That rise you'll see on the boost gauge is only because your drive pressure is going crazy. You'll over speed the turbo and your engine won't be able to clear all the exhaust on overlap.
     
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  3. LameMule

    LameMule Heavy Load Member

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    Headgaskets hate high drive pressure.
     
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  4. Idaho379

    Idaho379 Bobtail Member

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    Apr 8, 2021
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    At what psi does the K31 wastegate open?
     
  5. drewfarmsllc

    drewfarmsllc Bobtail Member

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    Oct 18, 2008
    South Carolina
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    Saw a 171702N at freightliner today. They said it's the same as original turbo.
    I thought this number was an upgrade. Am I missing something
     
  6. jamespmack

    jamespmack Road Train Member

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    Reason I run the 17702 is the way I drive id never notice it on the bottom end. I leave lights slow. But loaded down the 2 lane or interstate my egts are low. 900 I'm really working it. 950 I'm going up a steap hill. I seldom break 70 mph. Lots of 55 mph loaded in 10th/11gear. Gained a solid .25 mpg over stock Garret. 518hp to the rollers last dyno trip. Stock DDC tune.
     
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  7. DUNE-T

    DUNE-T Road Train Member

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    Detroit, MI
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    With stock turbo and stock 430hp, my max mpg was 6.7. With Fernando's 550/1850 tune and k31 turbo, I am at 8mpg with under 20klb running 70mph.
    Have not tested the truck with 702 and tune yet. Just recently rebuilt the engine and took it to Dyno, showed 570hp and 1950 TQ. Granted I drove bobtail, but still, 702 top end power is awesome, better than k31, but the turbo lag still annoys me with a 10 speed, even bobtail I feel it
     
    Last edited: Jun 9, 2022
    jamespmack Thanks this.
  8. jamespmack

    jamespmack Road Train Member

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    To each is there own. Its not a issue for my driving style. I do a yearly of 6.55 consistently. I've seen 4.8-8.75 on paper pump to pump. 75-110k gross. But I switch from covered wagon to hopper bottom. Neither is great.
     
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  9. little cat 500

    little cat 500 Road Train Member

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    Jan 17, 2010
    Abbottstown PA
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    k31 gate opens at 30psi I gave mine 2 turn tighter so I'm 35 now not sure that's good for it
     
  10. Idaho379

    Idaho379 Bobtail Member

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    Apr 8, 2021
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    Would the 171701 and K31 be big enough for a 600hp tune?
    With my stock Garrett the egt’s rise pretty quick on the 600hp setting.
     
    Bean Jr. Thanks this.
  11. little cat 500

    little cat 500 Road Train Member

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    k31 is not good for 600hp no lucky if its good for a stock 500
     
    Bean Jr. Thanks this.
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