HP And Torque's effect of Fuel Economy

Discussion in 'Ask An Owner Operator' started by bboweruo, Apr 27, 2008.

  1. bboweruo

    bboweruo Bobtail Member

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    Let say you have an aerodynamic tractor (Prostar, Cascadia, 387, T2000 etc.) and all the guts are the same (Rear end, Tranny, etc) except for differences in horsepower and torque....What do you guys think are you fuel economy differences going to be with a tractor that has 400 hp and 1650 lbft vs a truck that has 500 hp and 1850 lbft?? Is the difference going to be a lot??
     
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  3. D16

    D16 Light Load Member

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    Jul 11, 2007
    Vancouver
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    Depend where you haul.At Rockies you definitely better with higher torque and HP.At flat states you enough with lower torque and HP.Also it's matter your gearbox-I prefer 18 or 13 speed in mountain driving.:biggrin_2558:
     
  4. dancnoone

    dancnoone "Village Idiot"

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    The newer High Torque - Low RPM engines are the way to go, IMO.

    I drove a twin turbo cat for awhile, I loved it. It would pull itself to death, even at the lower rpm's. Fuel economy was good too.

    Check the specs for the DD15 by Detroit. It should be one hell of an engine.
     
  5. Donk

    Donk Have a Cup Of Concrete

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    Gear fast run slow. the age old formula for fuel economy.
     
  6. bboweruo

    bboweruo Bobtail Member

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    Bend, OR
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    I understand the gear fast run slow theory. My question though is really referring to fuel economy and if you the exact same engine (say a Cummins ISX for example) and you have two indentical tractors with the same guts in them. What (if any) is going to be the fuel economy difference if one tractor has an engine 400 HP 1650 lb/ft and the other tractor with 500 HP and 1850 lb/ft.

    I know that this is a totally theoretical question but I thought that the owner operators out there that have expereince with different tractors would be able to give us (me) noobies some insight.

    Thanks for all your replies. :biggrin_25514:
     
  7. dancnoone

    dancnoone "Village Idiot"

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    Mississippi
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    It will depend on the loads and terrain you run through. Both will get good fuel economy, if driven right. There will be times the larger engine gets better fuel economy, other times the smaller one will.

    It all boils down to terrain and weight, with the engines you have described...if spec'd and driven the same.
     
  8. The Challenger

    The Challenger Kinghunter

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    East Central FL
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    bboweruo,

    Check out a Volvo VNL or a International Prostar. FYI, Walmart is replacing its current fleet with International Prostars for the fuel reason.

    Hunter
     
  9. Bigray

    Bigray Road Train Member

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    Tampa, Florida
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    what's the scoop on the pro star's

    how are they performing

    what kind of mpg are they getting
     
  10. bboweruo

    bboweruo Bobtail Member

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    Mar 10, 2008
    Bend, OR
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    I'm with Bigray on this one....

    What is Walmart getting out of the Prostars and does anybody know how Walmart specs their OTR tractors?? Do they have APU's??? (I would tend to think so)
     
  11. 550hpW900L

    550hpW900L Road Train Member

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    Here is my experience with fuel millage, this is a large car W900L with a 290" wheelbase and enough room between trailer and sleeper to stick another sleeper there. When my truck was stock 550hp/1850trq i would get 4.2mpg, i later started to play with the fuel temp and boost wires and dumped the mufflers, average went up to 4.8. Now i have a tweaked ecm with a 2300rpm program and a hotter timing curve, marine 3406E 800hp cam and injectors, MI turbo stage 5 turbo. The engine should develop anywhere around 900-950hp and i get 5.5-5.7mpg running west coast, i always load heavy as well. I noticed running around IL, IN, MI on flat ground and slower speeds i see 6.5+mpg.

    The engine hardly works, and when you do push down on the throttle and see all the black smoke it just brings a tear to your eye.
     
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