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  1. #1
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    2011 cascadia dd15 fuel mileage

    Ok guys so I'm a trainee at prime and I'm with a lease driver who has a 2011 Cascadia. I've been around trucks my whole life, my father owns a few trucks and a heavy equipment repair shop. Well I'm stuck at prime and this guy is over the top with his fuel mileage. He has me shortshift the low side at 1200 which is fine. But on the highside when the truck is shifted at 1200 and the rpms fall to 800 it lugs. Wouldn't I just be better off shifting on the highside at 1400? I'm used to an old n14 lol also this man is telling me I shift too slow because I'm losing 400 rpms between gears, he insists the faster you shift the less rpms lost...... Opinions are appreciated fwiw on flats we get 8 mpg at 54 mph


  2. #2
    Road Train Member Pablo-UA's Avatar
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    My friend got salvage '10 Cascadia from USA, we did cab rebuild and fuel milage ~ 34 l/100 km with European tint trailer. So I cant see notisable difference with other engines

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    Road Train Member mustang970's Avatar
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    All your answers are right here.
    Download the DD15 brochure pdf file, you can print it out.
    Has graphs and charts with torque and horsepower curves.
    As you progress up through the gears, your shift points (rpm) should increase.
    http://www.detroitdiesel.com/engines/dd15/
    As far as dropping rpms when shifting, being your shifting a non-synchronized transmission, you are going to have a rpm drop when up-shifting.
    Start trying to speed shift, your going to clash, scrape or bang gears.
    Bottom line is, its his truck, Drive it his way (he's paying the fuel bill), when you get your own, drive it to your liking.

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  5. #4
    Road Train Member mustang970's Avatar
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    Interesting enough, watching a video released by Detroit Diesel (they might know a thing or 2) , they say the sweet spot of a dd15 is between 1000 and 1500 rpm
    Also, watch how the drivers in these videos shift, they are smooth through the gates, pausing between gears to match engine rpm to road speed.
    They are not hammering the gears like a muscle car.
    http://detroitdiesel.com/about/press...egory=training

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    Quote Originally Posted by mustang970 View Post
    Interesting enough, watching a video released by Detroit Diesel (they might know a thing or 2) , they say the sweet spot of a dd15 is between 1000 and 1500 rpm
    Also, watch how the drivers in these videos shift, they are smooth through the gates, pausing between gears to match engine rpm to road speed.
    They are not hammering the gears like a muscle car.
    http://detroitdiesel.com/about/press...egory=training
    Yes peak torque is 11 or 1200 I believe but what I'm saying is that 400 rpms drop from 1100-1200 on the highside the motor is starting to lug. Wouldn't u get better fuel mileage reving to 1350-1400 especially on inclines? When I drop a gear on a hill he makes me let the rpms drop to 1200 before I throttle down. In realilty its just making me drop more gears burning more fuel? Get a run for s hill .... That's unheard of

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    Road Train Member Pablo-UA's Avatar
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    really CRD technology is more flexible, so sweet spot is "wider" comparing with series 60 and that's why engeneers do not use so "sarp" torque limiting curve, like on series 60 and on MBE4000.

    Yep, I know that CRD is more sufisticated thing, less reliable, but as I can see MTU/DD/Mercedes made this engine after they can see all mistakes in other CRD engines for Class 8 trucks (Renault-Mack DCI 11, MAN/International D20-28 ) so seems to me DD13/15/16/OM471 are better.

    And I see that Mercedes Blue Tech unit is better and more reliable Bosch unit used on Volvo, Mack, Renault and Sisu.

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    Road Train Member crzyjarmans's Avatar
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    Well?, on a newer truck, I cant say, BUT?, a 400 gear step is good in my book

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    Shifting and Fuel Economy

    You will have a 400 rpm difference between gears, thats how the truck is set up. I drive a cascadia, and I shift differently depending on the weight of the load, grade wether ascending or decending, 4% or 6%, ect... I have a 9 speed and I shift differently from Bobtailing to pulling a Coors Beer load (44k lbs). The only time I touch the clutch is when I start rolling from a stop. Other than that, Im floating the gears. I can shift without ever touch the accelorater as well. I have recently had a 2 mpg decrease in fuel economy and I have driver the same truck the same way. I usually get 7.5 mpg, now Im seeing 3.5 to 5 mpg. A strong headwind tends to drop my economy at least 1 mpg. A tailwind increase 1 mpg. All depends on the driver, the truck, the load, and the road.

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    Quote Originally Posted by matt01887 View Post
    You will have a 400 rpm difference between gears, thats how the truck is set up. I drive a cascadia, and I shift differently depending on the weight of the load, grade wether ascending or decending, 4% or 6%, ect... I have a 9 speed and I shift differently from Bobtailing to pulling a Coors Beer load (44k lbs). The only time I touch the clutch is when I start rolling from a stop. Other than that, Im floating the gears. I can shift without ever touch the accelorater as well. I have recently had a 2 mpg decrease in fuel economy and I have driver the same truck the same way. I usually get 7.5 mpg, now Im seeing 3.5 to 5 mpg. A strong headwind tends to drop my economy at least 1 mpg. A tailwind increase 1 mpg. All depends on the driver, the truck, the load, and the road.
    Exactly. this guy is a trainer at prime it cracks me up. I had the opportunity to drive a 2011 w900L 550 cat 18 speed floated every gear and weighed 95,000 (overweight permit). Was told if it wasnt the end of the season I would have the job. It really blows that I have to go back out with this so called trainer but I have to stick it out untill I get my own truck.... This guy fails to realize the factors that effect fuel mileage and always criticizes when my fuel mileage doesn't meet his standards. Lets just say it gets old fast

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    Medium Load Member hrtbr8kr's Avatar
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    i loved my 2011 cascadia dd15. the rmp went well at 1200-1300 , i got it new and it took me about 23k miles to be able to float it, but my students drove me insane with not knowing the proper rpms to shift. there is no reasin for nonsmooth shifting in these unless you just dont have your rythm down double clutching or floating. i never seen my mpg under 8.2 fully loaded in the mnts. i seen it up to 12 on excellent days....i miss her ..sniffle sniffle

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