Kenworth Questions

Discussion in 'Ask An Owner Operator' started by Barricadebouncer, May 24, 2022.

  1. Barricadebouncer

    Barricadebouncer Bobtail Member

    Apr 11, 2022
    If I’ve posted in the wrong are, please direct me to what is appropriate. Thanks!

    I’m planning to buy my own truck towards the end of the year and have some questions.

    1) With the exception of the Studio Sleeper package, is there any size difference between the cabs on the T680 and the W990?

    2) Is the horsepower difference between 485 and 510 just an engine tuning program on the computer?

    3) If yes, can the shift points be better tuned so one doesn’t slow down to 25-30 mph going up the mouton I-70 west of Denver?

    4) Is it possible to get 7+ mpg when running 79+ mph?

    5) Is it possible to swap the high gears without affecting climbing ability so engine rpm’s can be reduced at highway speed to increase fuel economy?

    Thanks in advance.
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  3. Long FLD

    Long FLD Road Train Member

    Mar 4, 2015
    1) Same cab and dash layout

    2) EPA21 has cut back what’s allowed to be done with a computer. Basically they want the truck to stay as close to how it left the factory as it can. So not sure if you can tune them before they leave the lot or not.

    3) The computer will always try and keep the rpm’s in the optimum range. You’ll probably have to just shift it yourself and hold it in gear if you want to run higher rpm’s uphill.

    4) Not likely. But anything is possible.

    5) It will affect all the other gears and speeds too, not just your high end. Need to take startability and such into consideration. If you want a truck to run 80mph all the time it’s probably best to sit down and spec one out to make sure you get the trans and rears you want in order to achieve your goal instead of buying something off the lot and trying to change it.
  4. DUNE-T

    DUNE-T Road Train Member

    May 10, 2015
    Detroit, MI
    79+ mph . What freight are you planning to pull?
  5. Crude Truckin'

    Crude Truckin' Alien Spacecraft

    Oct 22, 2016
    North Dakota, Eh?
    I think the only way you're gonna do 7+ is keeping it below 70 and haul light.
  6. Brettj3876

    Brettj3876 Road Train Member

    Nov 18, 2014
    Stuck in Limbo
    You won't do 7 running 80. Or is it a typo and you meant 70? running close to 70 and not being heavy all the time you'd probably be close to 7 if you have Apu and don't idle
  7. Siinman

    Siinman Road Train Member

    Mar 5, 2017
    Kansas City, MO.
    Buy the new Volvo I Torque set up and you can get up to 8.5 mpg doing that speed.
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