Detriot Series 60 12.7 vs 14 Pros and cons

The 12.7 will run rings around cat when it comes to fuel, but the torque is only 1650. Very reliable motor. The 14 liter has had some issues as have all of them with the advent of all the emissions garbage. I believe the 14 might weigh a little more, but not much.

 

In a glider, you can get a non-EGR 14L. They are a bit heavier than the 12.7's, but lighter than your Cat. A 12.7 will get better mileage, but will have no where near the power that you're used to with a 550 Cat. Sticking with factory tunes, you can get a 14L with 1850 ft/lbs at either 500, 550 or 575 HP.

If fuel mileage is your #1 concern, go with the 12.7. If you want to compromise and get a little better mileage than your Cat and have similar power, go with the 14L. Gearing is important too, with a 14L, for performance, gear to cruise around 1500 rpm, for economy, shoot for cruising under 1400 rpm.

 

I tested the 14L way back in the late 90's when Detroit was thinking about releasing them out. The last setting mine had in it was 665 2250 and lets just say the So called King of the Mountain 600 Kitty was eating my dust up Every Single Mountain pass I hit fully Loaded. But then again I had experience driving monster power as at my First company the Owner had put me in his 850 HP close to 3000 FT LBS of torque Cummins that was special built for that truck. So for me it was just like going home.

 

The block and head on the 12.7 and the 14.0 are the same.
You can convert a 12.7 to a 14.0 with an overhaul kit.
I had a 2007 Columbia with a tuned 14.0 that would eat Kitties for breakfast, lunch, dinner and still give high 8's mileage.
I miss that truck, I wish I never sold it.

 

14L has a different crank and rods too, so it's not just an in-frame.

 

I got a 2016 Ws glider and like you I was torn between a 12.7 and 14L
I was used to a cat all my life so I went with a 14L factory reman. 2000 year pre emmision.

It was set at 550hp but was no match for a 550 cat.
I had leon tune the ecm and now I'm real happy with it.
I go 14L if you think your going to miss the cat torque.

 

I think if your hauling 5 axle light loads the 12.7 would be fine for best mpg.

But if your any bit of a power junkie and hauling more on the heavy side a 14L would be the way to go.

I have to say I do like this detroit thou, runs real nice.

 

I know a guy who calculated his fuel mileage out to be around 6 MPG with a DDEC IV Series 60 12.7L, 18 speed, 4.56 rears. Non-aero truck hauling logs.