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

Mike

Well-Known Member
Staff member
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?
 

mndriver

curmudgeon extraordinare
Supporter
You can spec the dd15 either 400/1750 or 505/1750.


The 1850 rating on the dd13 I was told is directed more towards the industrial trucks like dump, mixers and garbage type duty.

I need to look more into this.
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The new engines have the torque band starting around 975 rpm. So the 400/1850 DD13 with a DT12 is looking appealing to me at the moment.
 

Mike

Well-Known Member
Staff member
Something to consider.

DD15: B50 life of 1.2 million miles
DD13: B50 life of 1.0 million miles.
 

nan

Well-Known Member
Supporter
Our automatics have the DD15 and manuals have the DD13. I haven't noticed much difference in drivability besides the obvious transmission variable.

I guess they're spec'd the same.

I'd probably buy whatever was the better deal overall as a truck.
 

ironpony

Professional Pot-Stirrer
Supporter
Our automatics have the DD15 and manuals have the DD13. I haven't noticed much difference in drivability besides the obvious transmission variable.

I guess they're spec'd the same.

I'd probably buy whatever was the better deal overall as a truck.
They're totally neutered... you should know that.

I had my truck reset to factory spec, and it's amazing how much more driveable it is.
 

nan

Well-Known Member
Supporter
They're totally neutered... you should know that.

I had my truck reset to factory spec, and it's amazing how much more driveable it is.
I don't feel like we're neutered much. We have good pull, we just top out slow.

I mean, almost everyone is slow pulling 42k up a long 7% but I rarely downshift otherwise.

I tach ~1350 @60mph for what that's worth. Our USX Petes tached 1275 @65.

We don't grunt much getting the paper loads moving from a stop. Less than 20k and I can usually start in 4th.

For sh*ts and giggles I decided to see what would happen in 4th gear pulling out of Love's just a bit ago. I was coming home from Covington with 42k worth of paper rolls. It's flat exiting there, but it did move without stalling out. It didn't like it much, but it did it. 3rd is ideal and what I normally use. 2nd is for hill starts. I've never had to use 1st.
 
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mndriver

curmudgeon extraordinare
Supporter
You can get a 15 in higher torque will write more on this when I hav some time to type.
Be interesting to see that.

Spent about an hour yesterday going over a new cascadia spec sheet when I can justify getting out of my engine cost
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
Ok so, please keep in mind my information is a little over a year old, with the GHG 17 engine they were limiting production torq and HP availability due to trying to meet the fuel economy necessary for the epa requirement in production trucks. The Cascadia was selected as that truck, production switch with the end of the Coronado to the 122SD.

Now if your sales man is worth his salt and wants to make the sale they can put a 505 1850 program in the MCM/CPC or they can go with the 560 1950 that you can program into it. They order your truck and have the shop “fix it” when it comes in. Updated several for sales at the shops I worked at. With emissions choking everything down though I see this going away in the future.

The 122SD can be ordered with the 560 1950 set up or the DD16 which I believe is somewhere around 600/2050. I did not work on many of those so I don’t remember their exact spec sorry for that. But the SD is not the production truck being monitored for the GHG production program it will eventually have to fall in line or go by the way side.

Same with the SD program on the DD13 you can’t order that tune in an M2 business class but you can get it in an 108SD or a 114SD
 

mndriver

curmudgeon extraordinare
Supporter
Now if your sales man is worth his salt and wants to make the sale they can put a 505 1850 program in the MCM/CPC or they can go with the 560 1950 that you can program into it. They order your truck and have the shop “fix it” when it comes in. Updated several for sales at the shops I worked at. With emissions choking everything down though I see this going away in the future.
Anytime I talk to anyone about how to spec the truck, I get told some schmuck out in Oregon is going to do it for me and I get what they give me.

The guy I talked to yesterday was the first one to admit they could turn them up even a little bit.
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
Anytime I talk to anyone about how to spec the truck, I get told some schmuck out in Oregon is going to do it for me and I get what they give me.

The guy I talked to yesterday was the first one to admit they could turn them up even a little bit.
Yeah, most sales folks don’t know how to modify specs on the truck when they order it. A good sales person will actually do the leg work and build you an actual order sheet and not just use the standard check the block form which limits your options. It can be done. GHG 20 though may eliminate the possibility of this, it is also currently rumored that to meet em musings by keeping fuel economy peaked the production trucks of that year may have a permanent 60mph govonor.
 

Mike

Well-Known Member
Staff member
Having it turned up at the dealer before taking delivery sounds great. I wonder, however, how that will work with their IPM setup? Will cranking up the power throw that system in confusion?
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
Having it turned up at the dealer before taking delivery sounds great. I wonder, however, how that will work with their IPM setup? Will cranking up the power throw that system in confusion?
And that’s where I think your limits may come in because most auto shift trans aren’t rated for anything over 1850. And I may be wrong but if I remember from class correctly the DT12 is only warrantable at 1750.
 

Mike

Well-Known Member
Staff member
And that’s where I think your limits may come in because most auto shift trans aren’t rated for anything over 1850. And I may be wrong but if I remember from class correctly the DT12 is only warrantable at 1750.
But do you know what will happen with the IPM setup? I mean, after warranty, if truck is turned up, will this stuff still work correctly?
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
But do you know what will happen with the IPM setup? I mean, after warranty, if truck is turned up, will this stuff still work correctly?
Like I tell anyone who turns something past where recommended value is. What ever is your lowest rated component(usually driveshaft or transmission) just became your weak link. It’s all in how easy you drive it. Any shock load and that weak link will break.
 

Mike

Well-Known Member
Staff member
Like I tell anyone who turns something past where recommended value is. What ever is your lowest rated component(usually driveshaft or transmission) just became your weak link. It’s all in how easy you drive it. Any shock load and that weak link will break.
Completely understand that.

My question, though, is related to the operation of the IPM. When you are in cruise control and navigating hills, will this system still function correctly? I'm curious if this system is made to only operate under one configuration.
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
Oooh didn’t think of that, good point. However being as that system solely functions off of gps and adaptive cruise radar I don’t see why it wouldn’t.
 

Mike

Well-Known Member
Staff member
Oooh didn’t think of that, good point. However being as that system solely functions off of gps and adaptive cruise radar I don’t see why it wouldn’t.
Asked that because a while back, when I was specing out a new Cascadia midroof (that I didn't buy), the adaptive cruise only worked with the 10 speed. Why? I have no idea.
 

r3gulator3

Friendly Neighborhood Former Technician
Supporter
Asked that because a while back, when I was specing out a new Cascadia midroof (that I didn't buy), the adaptive cruise only worked with the 10 speed. Why? I have no idea.
That’s wierd as Hell, I just dont think your sales person knew how to do a build sheet. Or maybe they didn’t understand that On Guard which is made to interface with the automated transmission, is an adaptive cruise.
 
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