Important Poor milage in my lbz

Discussion in 'Duramax Diesel' started by ryan07lbz1, Oct 21, 2017.

  1. ryan07lbz1

    ryan07lbz1 New Member

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    I've been getting roughly 11mpg in my 07 ccsb lbz, the truck is on 33's and 20's but i feel like i should be getting better than 11mpg, the truck is bone stock, not even an exhaust is there anything i can do that will make a good difference ?


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  2. nickv

    nickv jewish misanthropist

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    11 mpg doing city driving? or highway?

    I got 12 mpg around town in my ECSB LBZ on 33s, all stock besides an exhaust delete. Got closer to 18~ on the highway. Sometimes more sometimes less.

    EFI live and a straight pipe will for sure improve your mileage as long as you can keep your foot out of it.
     
  3. Orange Sierra

    Orange Sierra New Member

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    "Bone Stock"? put it back to stock height and stock size tires and you will improve your mpg.I have seen soo many people destroy their mpg with a lift kit and bigger tires.Yes,some guys like the look but to get that look,you have to make sacrifices.I have a 01- z71 extended cab and enjoy a little better mpg than the window sticker states.19 hwy,16 city.Mods-KN cold air intake,cat back exhaust.
     
  4. TMAN

    TMAN Drive fast, take chances.

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    Efi live, exhaust, pcv reroute and egr delete will improve the mpg quite a bit. My lb7 gets in the 20s on the highway. I managed a 27 mpg average one time but that was pure luck in perfect conditions.

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  5. elkhornson

    elkhornson GMFS Member

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    Larger tires means more mass to spin and more air turbulence, which combined with lifting the truck will result in more air drag and trucks already have the drag coefficient of a brick. I see a big difference in fuel economy between 62 MPH where it is highest and 72 MPH so I can keep pace with speeding tractor trailer rigs. Drag increases with the square of the speed so going twice as fast results in 4x as much air drag to overcome.

    Worst part though is going to larger tires without changing the gears so the engine spends more time outside of its optimum power band and the transmission is downshifting more frequently.

    There is no free lunch - a concept most people have difficulty understanding or accepting. Want bigger tires you will pay a price in fuel economy and also reduced life for the front suspension and steering components.
     
  6. bml2200

    bml2200 GMFS Member

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    I get roughly the same, ~13.5 mpg, with a deleted truck making ~600rwhp, 4" lift, and 33's.
     
  7. Loki

    Loki Knuckle Buster

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    I get 18 around town in my 08. Full delete cai 4" straight pipe w/ tunes

    Hwy and I'm in the mid to upper 20s

    Stock height on 32s
     
  8. nickv

    nickv jewish misanthropist

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    i call BS on those highway numbers unless you're like 2wd and only drive 62 mph on totally flat ground. ive never heard of a big cclb getting 25+ mpg on the highway, hand calc'd
     
  9. TMAN

    TMAN Drive fast, take chances.

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    I got 27 mpg in my lb7 one time, 4wd, ccsb, lowered a bit with 20s and 32s. Doubt I'll ever see that again though lol.

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  10. Phildirt

    Phildirt n. fil-dert.

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    *coming down a hill with foot off the gas for 10 seconds
     
  11. TMAN

    TMAN Drive fast, take chances.

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    It was actually across 160 miles with about 1600 ft drop in elevation across it and a tail wind. And yes it was hand calculated because my old pos doesn't have instant or avg econ.

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  12. Phildirt

    Phildirt n. fil-dert.

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    Mine has average but it's not accurate. I gave up calculating mileage a long time ago though because suburban on 33s
     
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  13. TMAN

    TMAN Drive fast, take chances.

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    I drive like an idiot most of the time, I only calculate it out on longer drives when I behave myself. In the halfton with 35s I just don't want to know lol

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  14. Loki

    Loki Knuckle Buster

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    Well that's what I get, don't know what you tell you. Cclb 4x4...I don't drive faster than 65mph
     
  15. elkhornson

    elkhornson GMFS Member

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    "Efi live, exhaust, pcv reroute and egr delete will improve the mpg quite a bit. My lb7 gets in the 20s on the highway. I managed a
    27 mpg average one time but that was pure luck in perfect conditions."

    I do a calculation of total cost for mods like this and then determine how many gallons of fuel I need to save to break even on my cash outlay. Usually the breakeven point is 50,000 miles or more.

    Have you adjusted for the difference in circumference in your 11 mpg calculation? With stock gears the engine is going to spend more time outside of its peak power band which is around 1700 rpm's.

    Do you use an injector cleaner? Diesel fuel is incredibly dirty and even if a filter in theory removes 98% of the particles, that still leaves roughly 240,000 particles per gallon of fuel that are going into the injectors.
     
  16. Sledge42

    Sledge42 New Member

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    yup did that to mine also except no efi and get 21 winter in get 19
     
  17. Loki

    Loki Knuckle Buster

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    delete DPF too...ain't nobody got time for that :read:
     

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