14 Mack, 4.6 mpg? Can I get better mileage with it?

Discussion in 'Ask An Owner Operator' started by Starless, Sep 20, 2022.

  1. Dave1837

    Dave1837 Road Train Member

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    1500 @ 70 mph, 3.55 rears
     
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  3. Ridgeline

    Ridgeline Road Train Member

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    is it a delete truck and did you see if the dealer has an updated firmware for the ECM?
     
  4. Starless

    Starless Bobtail Member

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    It's deleted, not sure about the firmware side of things, the dealer I got it from can't really touch that kind of stuff
     
  5. Starless

    Starless Bobtail Member

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    I'm assuming you're pulling tankers from your picture though right? I also have a big ### metal bumper on my truck. I don't idle at all since my ac actually isn't working at the moment anyways. I don't think that all that wind drag alone could cause a loss of 1.4+ mpg though.
     
  6. bad-luck

    bad-luck Road Train Member

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    1530 is a high rpm for 70. How fast do you normally drive? Also if you call MACK with and give them your vin# they will tell you what gear ratio you have. I am guessing you have 3.90 or maybe even 4.11. I am assuming you have low pro 22.5 is thT correct?
     
  7. Dave1837

    Dave1837 Road Train Member

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    Yeah I pull a tanker. They're a lot more aerodynamic than a reefer but I'm running more hilly state routes than interstates, especially when running propane. I've never seen the 4's at all in this truck, high 5's and mid 6's all the time
     
  8. 77fib77

    77fib77 Road Train Member

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    Tires which brand, type.
     
  9. Starless

    Starless Bobtail Member

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    I would say I average around 65 mph with hills and all, I did ask mack and they said 3.2x, but I'm not sure if that's still what it is. Tires are 295/75R22.5.

    Gladiator 295/75R22.5
     
  10. ProfessionalNoticer

    ProfessionalNoticer Road Train Member

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    Check out the website below. You can figure out what RPM you want by tire size, gear ratio, final trans ratio etc.

    Spicer Transmission Ratio RPM Calculator
     
  11. bad-luck

    bad-luck Road Train Member

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    Ok, but unless you are running mountains your mpg should be much better, like in the 7's. I have a Peterbuilt 379 with a 3406E and I get mid 5's and I idle my truck constantly in the summer. I have an 18 speed and I am around 1450-1475 and I have 3.55's. I have 24.5 low pro's, when I had 11R 24.5's my rpm was even lower.
     
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