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5.9L Vs. 6.7L Cummins Diesel Engines - Cummins Vs. Cummins

Comparing The 6.7L And 5.9L Cummins Engines

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Intake and ExhaustDyno Numbers
We went back to Flash Auto to quantify the changes on the chassis dyno, particularly to see if the horsepower gains on the 6.7L would be as great as the 5.9L since it did not benefit from a full exhaust upgrade. With the Edge Juice in the Stock setting, the 5.9L gained 38 hp and 117 lb-ft of torque, and the horsepower peak rose 300 rpm. The 6.7L was even more impressive, gaining 64 hp and 158 lb-ft of torque with just the intake and exhaust. Clearly there are restrictions on the 6.7L besides the DPF and exhaust catalyst, since they were retained.Advantage: 6.7L Cummins

Performance Module Dyno Numbers
Turning the Edge Juice up to the Tow setting netted another 44 hp and 127 lb-ft for the 5.9L and knocked the horsepower peak down to a stump-pulling 2,200 rpm. The 6.7L gained 30 hp and 96 lb-ft of torque from the Juice's Tow setting. Turning the Juice up to the Extreme setting gained another 35 hp and 106 lb-ft of torque for the 5.9L, and 23 hp and 51 lb-ft of torque for the 6.7L.Advantage: 5.9L Cummins

Fuel Economy
The 5.9L truck was equipped with a 4-inch suspension lift and 35-inch tires on heavy 20-inch rims, and the owner was only getting 13 mpg in mixed highway and city driving. After the intake and Edge module were installed, mileage improved slightly to 14.5 mpg. When the Silverline exhaust was added, mileage improved to 16.5 mpg. "I had never been able to get 500 miles out of a tank of fuel before the exhaust was installed, but now I can," reported the 5.9L Cummins owner.

The owner of the 6.7L truck was not as scientific about recording his mileage, but he did experience a notable increase in mileage after the intake and module were installed. There also seemed to be another increase in fuel economy from the exhaust. The 6.7L owner was pleasantly surprised by the difference the exhaust made, considering that the factory diesel particulate filter and catalyst were both retained.Advantage: Tie

Conclusion
The 6.7L Cummins didn't show the same power potential as the 5.9L, but that's no surprise considering that it's saddled with so many emissions controls. What is surprising was that even with an increased stroke length (4.88 inches versus 4.72 inches), the 6.7L made peak horsepower at a significantly higher rpm than the 5.9L Cummins. The fact that we were able to get so much out of the 6.7L without affecting the DPF or throwing any codes spoke volumes about the quality of parts that S&B, Edge, and Silverline are producing.

As more 6.7L Cummins-equipped trucks hit the roads, we expect even more products to become available for them in the future, closing the gap between the new 6.7L and the trusty 5.9L. While the displacement may have changed, the Cummins B-series engine is still alive and well.


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241 comments
Cam Robison
Cam Robison

Dillon Zellhuber FYI ram does not own cummins lol

Ricky Amezcua
Ricky Amezcua

why hate on gas? we should be hating on prius and outback owners. my 460 can pull 70ft mobile homes so why go there?

Randy Bahl
Randy Bahl

Umm last I checked Cummins is there own corp business. Dodge buys there engines from Cummins. You can find your cute 12 valve Cummins in a case IH tractor

Randy Bahl
Randy Bahl

Umm last I checked Cummins is there own corp business. Dodge buys there engines from Cummins. You can find your cute 12 valve Cummins in a case IH tractor

Billy Underwood
Billy Underwood

Ford was bailed out by dodge? Wtf? Bought shares of ram so they could use cummins? Lmao! Ram don't own cummins.

Hunter Llewellyn
Hunter Llewellyn

Ford was bailed out by dodge awhile ago...needless to say they bought shares of ram and used the cummins motors in their heavy duty trucks such as their 450's and up

Zach Self
Zach Self

2010 an up 6.7 idk about the 07.5 to 09

Brandon Wood
Brandon Wood

Ryan Milliken do you see what I see on those license plates!?

Manuel Venzor
Manuel Venzor

The 5.9L is better! The 6.7L is ok. It would be a lot better if Chrysler designed a transmission to be able to handle it. The Cummins QSK45 sounds pretty gnarly right Patrick Hoisington?

Josh Fox
Josh Fox

WaaaaaaaaaaaaaI have toyotas! All over!

Craig Welch
Craig Welch

5.9 junk 6.7 is bigger better and beast

Steven Seeley
Steven Seeley

Joel Case Sr. Yea 9 sec on stock turbo and stock injectors dummy so try again

David Hubbard III
David Hubbard III

I gotta say I love my 1999 5.9..had to put the egde comp box and a better tranny but like I say when u see the smoke shes doin work..oh and its 197k on it

Joel Case Sr.
Joel Case Sr.

I worked for a ford dealer for years as a mechanic been a mechanic 20 some years have worked on damn near every make and model but the biggest p.o.s I've ever had the misfortune to come across is the 6.0 powder choke

Joel Case Sr.
Joel Case Sr.

Jacob Nikolas Aaron Mirlin u got a ttb ford and u got the balls to talk about a junk frt end what u been smoken

Joel Case Sr.
Joel Case Sr.

Got a first gen and third gen the 5.9 is as dependable as a hammer both of mine run there ass's off my 03 will smoke a new M3 its fn hilarious gets about 20mpg I sled pull drag race and regularly tow over 15, 000lbs

Trevor Myers
Trevor Myers

Both 05's I think but ima have to go with the 5.9

Walt Slover
Walt Slover

I recently got to see a 6.7 with a window rite next to #6, the rod fell out the hole onto our driveway!!!!

Jack Stout
Jack Stout

I think they ask these types of questions just to laugh at some of the ignorant posts.

Eric Salas
Eric Salas

5.9 wanna of dodge cummins best engines!!

Cody Simoncelli
Cody Simoncelli

If you hate a dmax perhaps you should stay away from diesels all together

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