X15 Efficiency vs Performance

Discussion in 'Trucks [ Eighteen Wheelers ]' started by rjs, Jan 12, 2019.

Which X15 overall?

  1. Performance

  2. Efficiency

Results are only viewable after voting.
  1. Mistabain

    Mistabain Bobtail Member

    5
    1
    May 23, 2017
    0
    Nope not at all lol. Frozen/refrigerated. Just was trying to maximize the fuel economy without sacrificing to much performance but it seems its one or the other nothing in between
     
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  3. Deezl Smoke

    Deezl Smoke Medium Load Member

    363
    189
    Feb 12, 2011
    Hillsboro Oregon
    0
    Ya, that's what they seem to say a lot of the time. But with 2.64 rears and no mention of the input torque rating of the trans, it can get spendy right quick like. If someone spec'd a truck new enough for the X Cummins, and at 400, the rest of the components were likely spec'd accordingly. Putting 2150 lb/ft in low gear to 2.64s is a whole lot of twist'n going on. But 1650 at 2.64 is likely a good match. That efficiency governs at 1750 rpm. I have it in my 2021 Pete 567 at 500hp, 3.25 rears. I wouldn't mind a bit lower numerical rear gears. At cruising speed, I'm at the high end of the "efficiency" rpm curve. That is according to the gauge anyway. I'd likely be happy with about 3.08s or so.
     
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  5. Mistabain

    Mistabain Bobtail Member

    5
    1
    May 23, 2017
    0
    Probably spot on with that assessment but I wasn’t thinking anything crazy where the components wouldn’t tolerate it, like 50hp and up to 1850tq. I hear 3:08 with a 13 speed is the way to go. But those are few and far between in my searches
     
  6. ravisidhu05

    ravisidhu05 Bobtail Member

    21
    10
    May 30, 2021
    WINDSOR
    0
    Choose at least 450hp go ex rating or smart torque don’t go for standard one I prefer you ex rating with hd driveline.
     
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  7. OhNoTerry

    OhNoTerry Light Load Member

    285
    458
    May 22, 2021
    0
    I’d go minimum 495-505ish HP with the cummins, especially if you’re pulling grades often. We know somebody who bought an itty bitty DD13 motor (first mistake), and with the small engine tied to the terrain he pulled, it worked the ever living piss out of that truck. The time it spent in the shop was a result of that as well.
     
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  8. Tmonroe94

    Tmonroe94 Bobtail Member

    1
    0
    Jan 27, 2022
    0
    2020 w900 565hp 2050torque heavy haul truck. 18 speed manual . Double frame. 46k rears. 4.30 gears . Pulling a walking floor trailer 75k to 85k most of the time. Sometimes heavier if the woodchips are wet. 2 hr round trip on some decent hills. About 20 min of pto time per load. Avg 5.5 mpg. Bumps out at 72 with stock rev limit. About 1800 rpm and stay their most of the trip. Doesn't even slow down hardly on any hills maybe 1 or 2 mph. Pretty impressive since on the same hills our 99 w900 with a 10 speed. 4.10 gears and 550hp 3406e drops About 8-10 mph on the same hills with the same loads
     
  9. Mistabain

    Mistabain Bobtail Member

    5
    1
    May 23, 2017
    0
    yikes. But wouldn’t expect anything more doing heavy haul. But your making the big buck you can afford that economy lol
     
  10. 2013Maxx

    2013Maxx Light Load Member

    133
    41
    Jan 17, 2018
    0
    Yea that 2020 has 15hp and 200 more ftlbs with a better transmission. The gap would be much closer if the ‘99 had at least a 13spd so you could split a gear.
     
  11. Roadrunner1970

    Roadrunner1970 Bobtail Member

    1
    0
    Sep 3, 2023
    0
    Company driver 2020 x15 efficiency series company castrated the he'll out of truck limited to 65 mph run alot from Dallas to muskogee,ok there's some hills along route truck can't even finish at 35 mph has 12 speed auto what I wouldn't give to have my old 03 379 ext nose Pete with 6nz and 18 speed manual I've never been a cummins fan and still not
     
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