Detroit DD13 vs. DD15: Which Engine Is The Best Overall for operating at 80K Gross or less, and why?

dd15.png

Buried in another thread on the forum, is the potential for a pretty informative discussion, one that may affect the purchasing decision of many current and future truck owners.

The question? Which is the better Detroit engine today for a typical 80K or less trucking operation? The DD13 or the DD15?

Both engines are more than capable of operating at 80K Gross.

DD15
  • Horsepower: 450-505
  • Torque: 1250-1750
DD13
  • Horsepower: 350-505
  • Torque: 1250-1850
  • 200 pounds less than the DD15
Keep in mind, we are not looking at past year models, but what is currently available now, and expected to be available in the near future.

Given the basic numbers: Horsepower and Torque, the number favor the smaller DD13 due to the increased torque capability. In addition to that, the DD13 weighs less, potentially increasing your payload.

How about some real world numbers from the membership here (if you are a guest, register and post your numbers). What are you seeing in terms of fuel economy? Which engine looks to stand up the best in terms of long term maintenance costs (including potentially costly emissions repairs)?

Large displacement engines seemed to become the normal for a while, as they were needed to compensate for failed emissions technology. Has the time now come that the emissions technology has finally caught up and we are able to once again operate more efficiently with smaller engines? Smaller engines did fine in the pre-emissions days, why not now?

dd13-engine.png
 
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Wasn't asking you. Too much truck for you.
Too bad it’s not a nice red...


Like radiant fire...,
 
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Since I am not able to learn I wrenched my repaired knee again. So instead of waiting for the pain and swelling to go away I rented a 2019 Cascadia. I did not want to be sitting around again. It had the DD13 and DT12 automated trans not sure of the HP and torque. Although I think it was lower than my 470hp 1650 torque 2016.
Not sure if my mileage will help much because my loads are light 19-20k one way empty back. What I found running from Woodland CA. over Donner on 80 to Idaho Falls ID and back was 8.3 mpg with rental and 7.5 mpg with my truck.
While my truck will run over Donner holding 50 mph rental would drop to 40 mph. The rental did the rest of the trip just fine and I even learned how to deal with the auto just fine. For example coming back down Donner I set the cruise at 55 and the truck held it there going down it would get up to about 58 before it started jaking and downshifting holding it to 55 mph. Of course that was almost always empty other trips 3-5k in it.
Overall I liked the DT12 and now am thinking of selling my truck and getting a new one with the automated trans. I do have someone who wants mine so hmmm.
Burned 4,590 gals in 38,170 miles.
I'm sure the MPG would probably drop when I got the DD13 with more HP.
Moral of the story don't drive a newer truck if you don't want to buy one. lol Anyone have any question on how one model did over the other I'd be glad to share.
 
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Since I am not able to learn I wrenched my repaired knee again. So instead of waiting for the pain and swelling to go away I rented a 2019 Cascadia. I did not want to be sitting around again. It had the DD13 and DT12 automated trans not sure of the HP and torque. Although I think it was lower than my 470hp 1650 torque 2016.
Not sure if my mileage will help much because my loads are light 19-20k one way empty back. What I found running from Woodland CA. over Donner on 80 to Idaho Falls ID and back was 8.3 mpg with rental and 7.5 mpg with my truck.
While my truck will run over Donner holding 50 mph rental would drop to 40 mph. The rental did the rest of the trip just fine and I even learned how to deal with the auto just fine. For example coming back down Donner I set the cruise at 55 and the truck held it there going down it would get up to about 58 before it started jaking and downshifting holding it to 55 mph. Of course that was almost always empty other trips 3-5k in it.
Overall I liked the DT12 and now am thinking of selling my truck and getting a new one with the automated trans. I do have someone who wants mine so hmmm.
Burned 4,590 gals in 38,170 miles.
I'm sure the MPG would probably drop when I got the DD13 with more HP.
Moral of the story don't drive a newer truck if you don't want to buy one. lol Anyone have any question on how one model did over the other I'd be glad to share.
Never say never but I’ll never run a new truck
 
I also forgot now that I took over running to Idaho twice a week instead of just running to Reno I am going to have to start sleeping in the truck.
So since when it gets warm I sleep like crud. I don;t want to idle so id I keep my truck i will have to add an APU for A/C not heat where I go it can get hot but I do well in the cold.
So my choices would be 1,Hotel 2, APU 3, New truck already equiped
 
You'll want an APU just so you don't idle the big Moto.

It's as much to prevent emissions after-treatment issues than anything else.
Exactly, up to now this truck has never been idled overnight.
 

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