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2.8L Duramax Review

Discussion in '2.8L Duramax' started by BoostN, Nov 3, 2015.

  1. BoostN

    BoostN Well-Known Member Staff Member Administrator

    8,111
    366
    Feb 11, 2008
    Tennessee


    Good video of the new 2.8L Duramax truck.. the only problem I see is the ratings/power compared to a full size 1500 (half-ton) EcoDiesel truck. As the EcoDiesel is all around a better truck payload wise and towing, with MPG figures looking to be close around 30MPG. Why spring for a smaller truck when a full size does this for you?

    Thoughts?
     
    Will L. and jrsavoie like this.
  2. Will L.

    Will L. Well-Known Member

    6,066
    3,443
    Jan 25, 2013
    Boulder City Nv
    Not a bad lookin rig, except that's the z71 pkg and the lower valance looks like it could barely clear a railroad tie.

    6,000 lbs!!?? That's what my hummer weighed from the factory. How the heck did they get it that heavy? That's why it isn't in the high 30 mpg range. They have a good start, but need to copy AMGENERAL, Ford, etc and use some aluminum.

    Think I'm going to go test drive one soon as I get a shot. $46k loaded sounds painful, but I haven't priced out its competitors.
     
  3. BIGR

    BIGR Lucky To Be Here

    4,158
    968
    Jun 9, 2008
    Appalachian Mountains
    2016 GMC Canyon gets a clean bill of health from EPA. 31 MPG for the 2 wheel drive model and 29 MPG for the 4x4. Writer of the article claimed he saw 35 to 38 MPG in a 4x4. Writer was probably relying on the on board computer data and not hand calculated maybe. Could the EPA be reporting low MPG numbers to try and discourage us from buying Diesels? Still not enough fuel mileage to interest me if they only get 29 to 31 MPG. I talked to a guy that has a gas burner 4x4 Colorado V-6 and he claimed he could get well over 30 MPG on the open road. So that being said what is the incentive to own a small diesel truck if the fuel mileage just isn't there? Most of us have our 2500HD trucks and we have any towing duties more than covered.

    One of you guys go and buy a Colorado Diesel pick up, try it out and give us some real time data.......:happy:

    http://www.foxnews.com/leisure/2016/03/17/2016-gmc-canyon-diesel-test-drive/?intcmp=hpff
     
    RI Chevy Silveradoman likes this.
  4. JayTheCPA

    JayTheCPA Well-Known Member

    1,482
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    Jun 13, 2011
    Annapolis, MD
    Minor difference of 700# additional towing capacity. Even so, I'd still reflexively pick the diesel if I plan to pull / haul anything; especially up or down grade.

    For comparison, have driven current generation Burb's (2013+) in the Rockies and if I had the option I'd chose a pickup with a full cab and regular DMax. On downhill grades, the recent Burb's allowed speed to quickly jump up 10 mph before any reaction occured (and this was *with* advance engagement of tow / haul). Granted I did not have an opportunity to drive a series of same years DMax on the same roads for comparison, and at the same time have friends with them and they repeatedly state that they just tap the tow / haul button coming down grade with their RV's in tow and do not worry about it.
     
  5. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,565
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    May 9, 2008
    ZEPHYRHILLS FL
    No, just turning tow haul on does not magically hold you back. For the newer trucks, you need to turn tow haul on, set the cruise control, and leave it on. Then the truck will downshift and engage the turbo brake to control speed going down a grade. If you turn the cruise off or intervene, then it stops holding you back. The ALLISON does have grade breaking where if your coming down a steep long grade, it can downshift and bring the rpm's up to 4800 rpms to aid in braking, but this is not automatic either. I believe the gassers also have a grade braking algorythim in them if it's used properly, but none of them have a completely automatic system per say.

    And if you're towing heavy, you should have tow haul on to begin with, unless you don't like your torque converter, and don't mind cooking your trans fluid.
     
  6. Ed HD

    Ed HD Formerly: Dad's 05 LLY

    3,107
    265
    Jul 6, 2008
    Lakeville, Minnesota
    My torque converter is a son of a bitch. :p
     
    Dunedain15 likes this.
  7. JayTheCPA

    JayTheCPA Well-Known Member

    1,482
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    Jun 13, 2011
    Annapolis, MD
    Good point. That was how I worked the Burbs and was not impressed (and that is how my friends with DMax's do it and are happy). Set the cruise, per-emptively engaged tow / haul, and watched what happened. Sometimes the Burb's speed jumped to more than 12 mph over my cruise set point before the system really did anything tangible to bring the speed back down. Ok, sure the ECM had kind of figured out that we were way over speed, but it was very slow to work on correction. When this happened I jumped in by manually downshifting even more than what the ECM had already done.

    The past 2 years were a little better than three years ago as the more recent ECM's seemed to eventually figure out that I was actually serious about speed control and over time would not let the speed jump up so far before attacking it. But in the end, I still had to force the issue through continual and proactive adjustment of the cruise control's set speed (based on grade) just to maintain a nearly consistent speed.
     
  8. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,565
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    ZEPHYRHILLS FL
    Anytime you do anything to intervene, the system shuts off. This happens alot where it increases speed, the driver steps in, then the system shuts off, and they think it doesn't work. It'snot going to be like hitting the brakes, and its not as aggressive as some would like, but GM has to try and set it up for the driver that wants it as well as the driver that doesnt. So in any case, its a compromise at best.
     
  9. JayTheCPA

    JayTheCPA Well-Known Member

    1,482
    632
    Jun 13, 2011
    Annapolis, MD
    Also good point.

    In each of the Burbs, dash displayed when the cruise was 'On' versus 'Active' (and IIRC even would indicate my desired 'Set' speed for the cruise control if I wanted to see it). During the scenarios the cruise control system looked and acted like it remained Active where my only manipulation was via the cruise control's Increase / Decrease set speed buttons or by pulling the transmission into Manual mode. Even when I manually dropped gears, the system still indicated the cruise control was Active and continued to behave that way as it did work toward the Set speed.

    The lower the gear, the better ability to stay close to my desired speed, but I wanted to leave it in full Automatic mode as much as possible to see what logic the system used. Although, there was one spot where I usually had it in 2'nd gear to keep speed tight as the local law liked to hang-out and enforce.

    So, Yes, I definitely appreciate that the logical design is a balance to meet a broad band of personal tastes. Also sense that the software engineers are addressing this as the past two Burbs seemed to recognize that I had a low tolerance for speed run-away given the variance seemed to decrease over time.


    Only point is that for actual duty in towing, the DMax is the better platform in the SUV / Pickup platform and am curious as to whether this will also play-out the same way with the Colorado.


    And just in case I seem negative about the current Burb, quite the opposite. They really are sweet rides :)
     
  10. btfarm

    btfarm 300,000 Worth Staff Member Moderator

    16,052
    1,334
    May 12, 2008
    Sandwich, Illinois
    So you're saying grade braking kicks off without cruise on? With the LBZ tow haul enables it as long as the switch is on. That seems kind of wrong.
     
  11. NVW

    NVW Well-Known Member

    8,423
    773
    May 5, 2008
    Castor, AB.
    Exactly, the last thing I want to use pulling a heavy load in hills, is cruise control.
     
    btfarm likes this.
  12. Will L.

    Will L. Well-Known Member

    6,066
    3,443
    Jan 25, 2013
    Boulder City Nv
    I agree, dumb design. Just do it like heavy equipment speed is regulated- you set the top speed by hitting the button at that speed. Then when the speed gets within a few mph, cut fuel. Too little fuel = low rpm and won't let it accelerate. Lock TC and it can't freewheel. If it has to downshift to do it, so be it.

    I know a lot of the systems use exhaust brakes, but cutting fuel and an air intake block off, not having to withstand the heat they can be made for much less money.
     
  13. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,565
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    ZEPHYRHILLS FL
    No, grade braking is active all the time anytime you touch the brakes. Starting mid way in 07 with the LMM, GM made it so the ECM could engage grade braking essentially via the cruise control. It was active brake control or something like that, but if you went x amount over your set speed, the ECM can command the TCM to downshift, then it can make it hold that gear while it works the fuel to control your speed going downhill. Then with the LML and medium duty trucks starting in 07, it could also bring in the turbo brake feature if it was activated to also help control your speed going down a grade. Problem is, most people hit the brakes before the system crosses the setpoint to engage the system, and disable, then say it doesnt work. They have to find a happy medium point for it to engage to try and satisfy a wide array of drivers, and the amount of speed before it engages is to much for some people. But could you imagine the complaints if the system kicked in instantly causing people to lose all there momentum because they just went downhill for a little bit before going back up another.
     
  14. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,565
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    ZEPHYRHILLS FL
    Thats how the system works, but you have to have some leeway in it for fluctuations to avoid it doing to much. If the trans has to rapidly downshift to hold speed, and itbrings RPM's up to 4800, it cant just bring the fuel back in as it has to drop below 3250 before itcan fuel again. So it has an anti business routine programmed in to try and avoid it falsely downshifting when not needed. And I'm sure many are thinking, well itcan just upshift real quick andbring the fuel back in to keep from losing speed if you rapidly go from downhill to uphill. Well the ALLISON by nature cannot just do this. There is many steps for it to shift, and it has to setup for each shift in advance, so it has to try and predict will the next shift be an upshift or a downshift.
     
  15. THEFERMANATOR

    THEFERMANATOR FRANKENBURBAN Staff Member Lead Moderator

    8,565
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    May 9, 2008
    ZEPHYRHILLS FL
    Many people expect a $70K truck to be able to run on the cruise in the mountains, and not only maintain speed going uphill, but also for it to do the same going downhill. You're in a minority when it comes to kicking the cruise off. Even I like to be able to just set the cruise, and let her roll when I'm towing the travel trailer. With mine I know I have to control my speed going downhill, but she does pretty good going uphill.
     

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