Pacar MX Engine fuel mileage

Discussion in 'Trucks [ Eighteen Wheelers ]' started by RDE1950, Dec 5, 2010.

  1. 98989

    98989 Road Train Member

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    any pictures?
     
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  3. king Q

    king Q Road Train Member

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    I like air suspension and agree that it works fine with the weights we usually run at and even at higher weights.
    We are exploiting ignorance I suppose , but we are way more expensive (60% more) then most of our competitors going in to countries like the DRC.
    They only use us because we have air suspension set ups and obviously only on certain cargo.
    Mainly the electrical guys as mentioned.
     
  4. JarradS

    JarradS Light Load Member

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    Perth, Western Australia
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    98989 Thanks this.
  5. The Bird

    The Bird Medium Load Member

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    White Rock, NM
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    Just finished a 36,000 lb run from Yakima, WA to Vista, CA and pulled a 7.4 mpg. I have a 2013 T700 with a 455 MX and a 13 speed. From what I've seen, keeping the boost below 20 lbs is the key to good mileage. I keep it between 1250 and 1450 rpm, and for this last trip, spent more time in 8 direct than overdrive to keep it below 60 mph.
     
  6. C571

    C571 Bobtail Member

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    Mar 24, 2013
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    Just got my 2014 389 with 485 MX, 13 spd. 22.5 tall, 3.36 gears. Only 1800 miles and avg. 6.8 mpg pulling hopper at 80000lbs loaded one way on a 350 mile turn. It uses .5 (one half ounce) def fluid per mile running 75mph with 2 good pulls one I'm down to 43 mph. It is turning 1510 rpms at 75mph in 13th.
    Very quiet, smooth but not a big horse. It is comprable to my 01 379 with a C-12 at 430hp, maybe just a little more. Hope this helps!
     
  7. king Q

    king Q Road Train Member

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    Im not saying you are guilty of this but often when a truck runs smoother and quieter it is perceived as being slower and less powerful.
    I remember one of our drivers who drove a 360hp 2636 V10 Mercedes that had a loud raspy growl when you stepped on the loud pedal.
    We switched him to a 430hp much more modern truck and he complained that it lacked grunt (meaning power).
    We had to show him the difference in ave speed up climbs to prove to him that grunt and performance don't always go hand in hand.
    Having said that when we de-cat the exhaust systems and put better flowing silencers on then they gain both a bit of grunt and performance.
     
  8. daf105paccar

    daf105paccar Road Train Member

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    You run long times at 1510rpm/75mph for long times?

    If so,i hope you don't pay for the fuel.
    That rpm is very high for getting the best MPG.:biggrin_25525:
    The MX like it in the slow rpm's.
     
    fland Thanks this.
  9. 98989

    98989 Road Train Member

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    how much does your have rpm on which speed?

    i found that 1400rpm is very good for performance(like long climbing) and similar and should be downshifted halfgear at 1250-1300

    , and this should be cruising speed for those who drive here offhighways , cousins have 1150rpm at 89 (16speed manual from 2007) and that is too fast most of times no need for 8th gear other is slower
     
  10. 98989

    98989 Road Train Member

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    also many thinks that common rail engines are weaker because there is no power eruption but power is more linear over wider band
     
    king Q Thanks this.
  11. C571

    C571 Bobtail Member

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    Mar 24, 2013
    south west
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    I've been driving this route for 36 yrs. so it is not that I percieve less power because it is quieter, I do understand what you are saying though. I'm leaving in the morning and will drive 65 instead of 75 and see how much difference it makes.
    It sounds like I should have geared it higher, I also seen on paccar's website that they are offering a 500hp 1850 tq version now? When I ordered the truck in Jan. the salesman told me the 485hp 1650tq was as big as I could get. Too late now but I would have waited if I'd known, my fault for not being informed!
     
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