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18.4 MPG!

Discussion in '6.9L IH & 7.3L IDI Diesels' started by nitroguy, Jun 8, 2019.

  1. nitroguy

    nitroguy Full Access Member

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    Just came to post that. I couldn't believe it. My first fill up was 16.5mpg, and I thought it was a fluke it was so high. Then the next tank yielded the impressive 18.4! My last truck, a 2002 Dodge ram 1500 would get 10.5, so I'm thrilled! I drive mostly country type roads with lots of slowing down for curves or stop signs then up to 60, then back down.
    From what I can tell, the truck (Red Fred The Rusty Ol Flatbed) has 3.73 gears, 4sp transmission, and a na 6.9. I still need to change out my diff and tranny fluids too, which I can imagine will only help!

    Long story short - goodness I love this truck! It inexplicably brings all kinds of joy and delight when I chug down the road.

    Keep on trucking!

    20190604_193536.jpg
     
  2. Macrobb

    Macrobb Full Access Member

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    I'm honestly curious. It sure seems to me like 6.9s get better fuel economy than 7.3s do. They also seem to run smoother for some reason...
    I wonder if it's due to the head design differences on 7.3 for emissions...

    edit:
    With a 7.3, turbo, 5-speed, GVOD, and 4.10s, the best I ever got was 18.5 on a straight highway trip of a full 8 hours or so, at 50-60MPH(so near perfect conditions).
     
    Last edited: Jun 8, 2019
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  3. bbjordan

    bbjordan Snow Monkey

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    I'm very happy with my 6.9. It got 8.6 km/l (20 miles per US gallon) on the last trip to the farm. That's with 4.10 gears, 305/70R16 tires, ZF-5 trans, in 2WD with hubs unlocked, and no fan on the engine. I travel at 100 - 110 km/hr (60 - 70 MPH).
    Got lucky and had the wind at my back both ways. :)

    Edit: that's running my WMO fuel cocktail: 85% WMO, 10% RUG, and 5% BioDiesel.
     
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  4. franklin2

    franklin2 Full Access Member

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    It's very difficult to get high mpg numbers with the latest fuel you can buy at the pump. They zapped it for emissions.
     
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  5. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I typically average around 17 in the shop truck just running around empty in town, in a recent trip from Lubbock I got 23 mpg. That’s with no fan or filter and my other few mods.
     
  6. nostrokes

    nostrokes Full Access Member

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    "Other few mods".... :rotflmao:rotflmao:rotflmao:rotflmao:rotflmao

    Best I could ever do was 15... E4od extended cab and turbo... Oh yeah 4.11 gears ..
     
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  7. Selahdoor

    Selahdoor Full Access Member

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    Whats with no fan? Is no one concerned with engine overheating?
     
  8. Jason1377

    Jason1377 Supporting Member Supporting Member

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    I believe some run it as a mod or turbo people have a intercooler wes has his shop truck nodded figured for him testing new products.
     
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  9. david85

    david85 Full Access Member

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    I first did the no fan mod years back. It works fine as long as you are at speed. For a few years, it became part of my seasonal routine to remove the fan for winter driving. Made a big difference in the warmup zone of the driving cycle because I was never able to get my fan clutch to stay unlocked when cold. Even after replacing it, the new one was even worse. I know it's burning extra fuel, but I don't have time to fiddle with it lately. I've long dreamed of an electric conversion but I don't have the time right now.
     
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  10. Selahdoor

    Selahdoor Full Access Member

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    BTW: this is one of the reasons I am working to get my "new" truck on the road.

    There is a problem with overdrive, in the E4od. But even with that problem, it supposedly gets 15mpg.

    My other truck... 6 to 9 mpg if I am lucky...
     
  11. Oledirtypearl86

    Oledirtypearl86 Full Access Member

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    I pull a consistent 17 at 55mph with a crew cab long bed , F-350 with a t19 and a 6.9 till I get a out of Towner on my tail then I black them out till the turbo catches then I'm at a break neck speed of 65 or so
     
  12. bbjordan

    bbjordan Snow Monkey

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    I'm not, but I live in Calgary Alberta, north of the 49th parallel. At my brother's farm, about 4 hours north, he had ice in the bird bath this morning! If I lived in Southern California or Texas I might be concerned.

    I still have the winter front on my truck.

    It depends on your situation. I mostly use my truck to haul stuff back and forth to the farm, so mostly highway travel. I've never had a problem, even towing one of my trucks to the farm!

    The only time it has come close to overheating was getting stuck in rush hour traffic in the city: stop & go traffic.

    A couple winters ago, I was picking up an engine for my brother, and left my truck truck running because it was -30C out. After BS'ing with the guy for 10 -15 minutes I realized I had left my truck running. I ran out expecting it to have overheated. Nope. It actually lost heat and had cooled down! That is how efficiently the 7.3 PowerStroke runs at idle.

    I figure there's a couple of advantages to not running a fan.
    1. Increased fuel mileage due to less HP robbed.
    2. Longer water pump life due to not having a big weight wobbling around on the front of the pump shaft.

    Of course, overheating the engine can ruin your day, so plan B is to open the windows and turn on the heater full blast. It's no fun, but I'd do that for my truck. In fact, I have done that. :)
     
  13. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    I live in south Texas and dont run a fan, Ive got the cooling mod done to this engine (and all my engines) and dont have an temperature issues. If I sit idling for 20-30 minutes idling in traffic in 100* temp coolant temp will come up to 220, but I as soon as I start moving or bring rpms up the temp comes back down.
     
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  14. Selahdoor

    Selahdoor Full Access Member

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    Now I'm off to look for "the cooling mod"... :)
     
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  15. chris142

    chris142 Full Access Member

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    And the more they sell the more they get back in taxes.
     
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