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

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?
 

Rigjockey

I am don't know.
Supporter
Live is like a box of chocolates....
Life IS like a box of chocolates.
Sooner or Later you are going to run into a NUT! ;):p:thumbsup:
 

InTooDeep

Well-Known Member
I like the autos on grades and in traffic.

I hate the autos finessing under a trailer and into a dock.
I did drive a loaner 2016 when my truck was having front end work done it was a bitch backing under a low loaded trailer, the 2019 not so much. The new truck acted much smoother backing that slam dance into the pin didn't happen.
 

Mike

Well-Known Member
Staff member
I like the autos on grades and in traffic.

I hate the autos finessing under a trailer and into a dock.
Auto is fine getting under a trailer if you have an air dump like all trucks should.

New autos supposedly have some progrmamming to assist with backing as well.
 

Electric Chicken

Well-Known Member
Supporter
Auto is fine getting under a trailer if you have an air dump like all trucks should.

New autos supposedly have some progrmamming to assist with backing as well.
Not that. The throttle tip in. All or nothing. They aren't smooth to engage, at least on Schneider's super duper fuel economy above all else programming. They go to neutral at every opportunity.

One second you're sitting there in reverse but neutral. A little throttle does nothing then BAM! you're nailing the pin.
 

ironpony

Professional Pot-Stirrer
Supporter
Auto is fine getting under a trailer if you have an air dump like all trucks should.

New autos supposedly have some progrmamming to assist with backing as well.
Not that. The throttle tip in. All or nothing. They aren't smooth to engage, at least on Schneider's super duper fuel economy above all else programming. They go to neutral at every opportunity.

One second you're sitting there in reverse but neutral. A little throttle does nothing then BAM! you're nailing the pin.
Schneider bought the cheapest version they could get away with.

Programming to assist backing? Nah!! Next thing ya know, they'll want seats that don't give them permanent spinal damage!

:mad-97:
 

Rigjockey

I am don't know.
Supporter
One old School trucker used to come into the plant and he was bitching about the clutch needing to be rebuilt on his automatic. Buddy used to sit there in a pot hole and because the truck was not moving, he figured he could just let off the brake in gear and everything would be just fine. :D
 

Humble pie

Hated by everyone... loved by all
Supporter
70k is the number I was looking at recently. Just looked it up, and it's actually 75K.


Basing on efficient long haul, which is why I mentioned minimal idle previously.
Why would you go with the DD15? The DD13 will actually put out more torque.
 

Humble pie

Hated by everyone... loved by all
Supporter
I'm on the fence with the two engines, but even the DD13 is 65K

The only reason they still offer the 15 is because people think they need a 15. That is what the dealer told me. The 15 is only rated for [email protected] The 13 will go [email protected]
 

Mike

Well-Known Member
Staff member
The only reason they still offer the 15 is because people think they need a 15. That is what the dealer told me. The 15 is only rated for [email protected] The 13 will go [email protected]
Opened that can of worms up quite some time back.


Still undecided
 

Humble pie

Hated by everyone... loved by all
Supporter
Opened that can of worms up quite some time back.


Still undecided
I don’t know why they still carry it. Get a 13 or a 16. No need for the 15.
 

Mike

Well-Known Member
Staff member
I don’t know why they still carry it. Get a 13 or a 16. No need for the 15.
They push the DD13 as a regional operation engine. When I was spec'ing a truck, they pushed hard to sell me on shorter gears if I went with the 13 litre engine, even though they were rated the same. Couldn't get a straight answer as to why when both had an 400/1750 at the time.

Those who are operating the DD13 seem to be very pleased with it, though.
 

Humble pie

Hated by everyone... loved by all
Supporter
They push the DD13 as a regional operation engine. When I was spec'ing a truck, they pushed hard to sell me on shorter gears if I went with the 13 litre engine, even though they were rated the same. Couldn't get a straight answer as to why when both had an 400/1750 at the time.

Those who are operating the DD13 seem to be very pleased with it, though.
It’s was mentioned briefly when I ordered mine. The reason I shut it down was resale value. Who is going to buy a heavy haul unit with a 13L motor? I have no doubt that it would do it, but it’d be hell to try an unload later. I mean you are running a 12.7 liter motor, do you have any complaints? The 12.7 470 horse was a good strong engine.
 

Mike

Well-Known Member
Staff member
It’s was mentioned briefly when I ordered mine. The reason I shut it down was resale value. Who is going to buy a heavy haul unit with a 13L motor? I have no doubt that it would do it, but it’d be hell to try an unload later. I mean you are running a 12.7 liter motor, do you have any complaints? The 12.7 470 horse was a good strong engine.
12.7 works great for me. Engines went big to deal with emissions. That’s all been figured out now, so the sizes are coming back down.
 

BlackBart

Shorebilly
Supporter
12.7 works great for me. Engines went big to deal with emissions. That’s all been figured out now, so the sizes are coming back down.
Had that problem even with little trucks

Fix it again Tony went from the 5.9L cummins to the 6.7 only to make up for the performance losses they knew they get from emisson crap
 

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