Why/How is the Cummins in our trucks so "underworked"?

[Intelman34]

I have what you could call a dumb question.



I hear everyone always saying how the Cummins in the Ram is so underworked and how it never really gets "tested" and used.



I never hear this being said about the PowerStroke or the Duramax.



The Cummins doesn't have anymore HP or Torque than the other two so why/how is it underworked?



Thanks!

 

[MPatrick]

Overworked

Because the CTD was built for Dozers!



The actual max load for the CTD is substantial.

 

[Diesel Freak]

the ISB is a 300 HP engine that has been detuned for use in the Dodge application.



For motorhomes, it makes 300 HP, and 660 FTxLBF



in agricultural apps, it can make 275 HP, and 730 FTxLBF

 

[Rams-n-Hogs]

From my understanding of the CTD, it was originally designed for use in a 65000 lb truck, and was detuned for the Dodge. Don't remember where that came from, it was about 7 years ago. (When I bought my truck).



Jim

 

[CRSmith]

The latest round of Hyundai front end loaders here at the DOT maintenance yard all came with 5. 9L cummins, if that tells you anything.

 

[HEMI®Dart]

Sterling Acterra Model 8500 66,000 lb GVW Cummins ISB is Optional.



http://www.iowatruckdealer.com/acterra/specs.html



#ad

 

[HBarlow]

The Cummins B engine was designed to be used in medium duty trucks including Class 7 trucks with gross combined weights up to 65,000 pounds. It is one of the available engines in medium duty Freightliners like the FL-60, FL-70, and other medium duty trucks.



I've got an old 1995 or 1996 Dodge truck brochure which brags about the original use for the Cummins engine being in medium duty trucks up to 65,000#.



Dodge engineers approached Cummins later to see if the Cummins could be fitted into Dodge pickup trucks.



Ford's F-750, its largest medium duty truck, did offer (I haven't looked at the most recent models) the Cummins ISB as an option for GCWRs higher than 30k or 33k pounds, I forget which. The Navistar Powerstroke was not an option at this level.



It is a fact that the Cummins is loafing in Dodge trucks pulling trailers that far exceed Dodge factory limits.



When you travel the interstates you'll frequently see Dodge 3500s in commercial hotshot service pulling huge gooseneck trailers hauling industrial equipment and other very heavy loads. Some of them are probably at 35,000 to 40,000 pounds gross combined weight. Illegal of course and violating their Dodge warranty, but they're doing it. The Cummins engine doesn't mind.



An interesting fact I learned from someone on the TDR forums: The Cummins engine's federal data plate mounted on the front driver's side of the engine identifies the Cummins 5. 9 as a "Medium Heavy Duty engine. The same federally mandated data plate on Ford Navistar or Chevy Isuzu engines identifies them as: "Light Heavy Duty" engines.



Harvey

 

[QRTRHRS]

Not to denegrate the 5. 9 but for ~65K gross, I would want something bigger.

 

[CROW]

Since I am basically computer illiterate, I can't post it, but there was a picture here on the register of the rods in the 5. 9 Cummins, new 6. 0 Powerstroke and the Duramax. A glance at the rods relative sizes will give you an idea of the robustness of the 5. 9 Cummins motor. (Shovelhead posted the picture on 3/28/03). I would like to know the comparative weights of the three rods. The 5. 9 is truly an industrial grade motor.

 

[WadePatton]

Rods by Cummins

#ad

 

[Evan A. Beck]

No to downplay the mighty 5. 9, but... ... ... .



Anything over about 30,000 lbs GVW is too much for the 5. 9, 12V or 24V. At 30K, even with power add-ons, the 5. 9 feels anemic. Works great for some medium duty trucks and stuff, but when it comes to moving a heavy load uphill, there's no replacement for displacement. Give me a C or L series engine, mechanical or electronic!



Yeah it may be rated for 65K gross, but it'll be an awfully slow ride up the hill.....

 

[Vaughn MacKenzie]

I heard that the 5. 9 Cummins generally has a lifespan around 250,000 miles in heavier applications, so when it's worked hard it'll shorted its lifespan, especially if you crank up the power. Although I did see on the Diesel-Stop board one guy hauling heavy in a F750 (I think) or Freightliner with a turned-up 5. 9L and it was doing OK at 550,000 but was starting to get tired.



Vaughn

 

[Skydiver]

Remind me again.

How many main bearings our 6-cylinder has compared to the mighty v-8's?

I thought the last score was something like 7 to 5.





Cummins wins!

And while were at mains,what are the diameter of ours verses theres.

Tim

 

[HEMI®Dart]

Even though @ 60,000 GVW, an ISB Cummins might not be the best choice, at least it is offered and approved by Cummins and the vehicle manufacturer. You won't see a duracrap or powerchoke offered as an option in a truck that size.

 

[Jff24Gordn]

Here we go, a 148hp 6bt in a truck rated at 80,000 pounds.

http://www.ottawatruck.com/ottawa_products/c30_offroad.html

#ad


can move at an astounding speed of 25mph with gears to make any rockcrawler jelous.

 

[HEMI®Dart]

A 50 Ton RTC-8050 Series II Rough Terrain, 72,495 GVW Link-Belt Crane. B5. 9 powered.



#ad




http://www.linkbelt.com/lit/products/frameproducthome.htm

 

[Big_Daddy_T]

My buddy works for a long haul company. He loads the trailers and ties down the loads. He also weighs them to set them up for the highway. They have a truck like JGordon showed rated at 86 or 92 k(dont remember) for moving around series of loaded trailers in the yard. He was impressed cause it takes a 12-15 liter to get it down the highway but a 5. 9 moves it around the yard.

 

[dpuckett]

Back to how they are so underworked. My father has a 90 Cummins shop manual, with all B series applications listed. For over I believe 250 hp, an inline CAV pump was used. Ratings went up to 300 hp and probably in the neighborhood of 800 lb ft, though that wasnt listed. Keep in mind these power ratings were originally made in the mid 80s; designed in the late 70s- early 80s. Chevy's original 6. 2 made a whopping 130 hp; Ford's 6. 9 around 165.



I believe this year marks 20 years of the Super B. Now, the new ones may be rated for 305 hp, which is probably more accurate and useable than Ford's 325 hp, but the torque rating per hp is lower than my 91's 160/400.



The connecting rods are only part of the story. While Ford may have had the biggest DISPLACEMENT diesel in its class, the fact of the matter is, Dodge has the BIGGEST diesel in class at 1000+ lbs fully dressed, compared to 800 or so for a 7. 3 gutless bomb. While the hp to weight ratio may look bad in the pages of Car and Driver, et al, it is a sign that the Cummins will still be hummin long after the others have died.



One more point, Dodge has kept the same displacement, and basic design for 15 years- 5. 9L, I6. Hmmm. How many times have Ford and Chevy changed their engines, trying to keep pace? goes back to the simplicity of having all your ducks in a row, or in this case, cylinders.