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1200 mile trip

Discussion in 'GM 6.5 Diesel Engines' started by Deere Freek, May 5, 2008.

  1. Deere Freek

    Deere Freek Recruit

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    May 5, 2008
    Hastings, MI
    Just found out about this forum, spent most of my time on dp, anyway, to my question. I'm looking for ways to increase my mileage (whi isn't) and thought about shutting down a couple cylinders (only run on 5 or 6) just while cruising. Is it possible or would it be more work than it's worth? I know that a lot of larger vehicals on the road are doing it and wondered if it was possible for us 6.5'ers. I'm making a trip from Mi to Ia this weekend and came up with the idea.
     
    Last edited: May 5, 2008
  2. iamdave0887

    iamdave0887 Here Comes Chaos.....

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    May 5, 2008
    CT
    the cylinder shutdown thing hasn't worked well in the past. the caddys with the 4-6-8 engines that were "fixed" to just run on all 8. the new "displacement on demand" GM engines are garbage i've heard. my neighbor had one and even running on the 4 cyl it was still getting single digit numbers for fuel mileage. its probably more pain and BS than its worth, but thats just my $0.02.
     
    Last edited: May 5, 2008
  3. Deere Freek

    Deere Freek Recruit

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    May 5, 2008
    Hastings, MI
    I guess i figured it would be. normally I'm not one to come up with all the bright ideas but figured i would ask the epxerts
     
  4. Green Machine

    Green Machine Truck Don't Smoke... Well...

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    May 5, 2008
    Ohio
    Yeah, I don't think cut outs would work for 6.5s since they are not electronically controlled. And your from Michigan?? I feel bad for you... :p
     
  5. Acesneights1

    Acesneights1 New Member

    10,018
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    May 5, 2008
    Northeast CT

    Hahaha I remember those duds
     
  6. iamdave0887

    iamdave0887 Here Comes Chaos.....

    1,657
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    May 5, 2008
    CT
    :smilielol5: they worked "fine" if you consider "fine" being in the shop more than on the road. that sounds like the new ford 6.4. :prrr:
     
  7. oil pan 4

    oil pan 4 Recruit

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    May 5, 2008
    Electric fans seem to have gotten me about +2mpg with a mix of city and high way driving.
     
  8. WanaDmax

    WanaDmax New Member

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    May 4, 2008
    Pleasanton, CA
    I asked this before on DP

    And the answer went something like this:

    Diesel engines run full compression all the time, as opposed to gasoline engines, which run different comp ratios all the time.

    When you shut the injectors off to the diesel cylinders, you take the fuel out, but you get the HUGE surge in extra cylinder pressure, because those other non working pistons are just adding drag.

    So you would be adding more fuel to compensate for the compression, therefore reducing fuel econ and engine life...

    Sound legit?


    And as for the gas engines varying there compression ratio, dont ask me how its done. I though they would be fixed or something.

    (25% or more might be wrong. im no expert)
     
  9. NVW

    NVW Well-Known Member

    8,338
    702
    May 5, 2008
    Castor, AB.
    Normal gas engines are fixed comp. ratio. I think what they may have been referring to are the cyl's. that are dropped. They have a means of holding the valves open to to reduce the drag. If they made comp. but with no power stroke it would be a worse case scenario. Leo
     
  10. High Sierra 2500

    High Sierra 2500 Recruit

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    May 4, 2008
    Yeah, all engines have fixed compression ratios. At least so far... Nobody that I know of has figured out how to make it variable. When that happens it will be a scary day... But I expect to see camless engines much sooner, and those will be strange things.

    Shutting off cylinders in my opinion wouldn't do much good. It still requires the same amount of power, but now other cylinders have to produce the power to keep the ones that aren't firing moving. Just creates imbalance and that's about it. Plus, how you would do it on one of these engines I'm not sure. On a fuel injected gasser it is as simple as shutting off an electrical pulse to the cylinder you want to shut off, but you can't do that on one of these engines.
     
  11. iamdave0887

    iamdave0887 Here Comes Chaos.....

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    May 5, 2008
    CT
    high sierra. theres only one engine that has been made thats variable. the prius engine is "atkinson" cycle. its has a variable comp ratio by adjusting when the intake valve opens. its a stupid deisgn thats bound to break but i thought it was "interesting". its the only thing i've learned in my hybrids class:prrr: that i found useful this semester.
     
  12. oil pan 4

    oil pan 4 Recruit

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    May 5, 2008
    Saab did make a variable compression ratio engine back in the early 1990's. As you can see it never went any where.
    The GM LS2's with displacement on demand use solenoids on the hydraulic lifters' oil supply to collapse the lifter shuting the valves, this helps with pumping losses and of course the fuel injector stops too.
     
  13. Deere Freek

    Deere Freek Recruit

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    May 5, 2008
    Hastings, MI
    So from the responces I'm getting i'd say that it's not very practical. I know on my Kubota I have a compression realease valve for easier starting. Would that not make less resistance?
     
  14. iamdave0887

    iamdave0887 Here Comes Chaos.....

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    May 5, 2008
    CT
    the comp release idea might work. that type of setup varies with different engine companies and such. my dads got a 65-70cc chainsaw with a comp release because without it you can't pull it fast enough even two-handed. my friends honda 4-wheeler has a comp release as well. you click it on ans its much easier to pull over although you can start it without the comp release but it may backfire and pull back(ask me how i know)
     
    Last edited: May 6, 2008
  15. Deere Freek

    Deere Freek Recruit

    333
    0
    May 5, 2008
    Hastings, MI
    i've done that with my saw. trust me it hurts. squirming on the ground like a worm thrown on hot coals.................




    no fun
     
  16. 94K30

    94K30 Diesel nut

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    May 9, 2008
    manchester CT
    OK Dave, How do you know?
     

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