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Open Roads Forum  >  Tow Vehicles

 > 6.7 Cummins vs 6.6 Duramax

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SoonerWing03

Oklahoma

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Posted: 03/30/19 07:51am Link  |  Quote  |  Print  |  Notify Moderator

As someone who knows next to nothing about Diesel engines, I am trying to figure out the strengths and weaknesses of these to. Any opinions would be appreciated.

mowermech

Billings, MT

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Posted: 03/30/19 08:18am Link  |  Quote  |  Print  |  Notify Moderator

Cummins: Tougher than an old boot. Fewer parts. Mine has 410,000 miles and still going strong.
Duramax: Tough. More parts to wear. At one time, the connecting rods were lighter than those in a Cummins. I don't know if that is still true.
Of course, there are those who just can't stand to own an I-6 engine, they have to have a V-8. Many years ago, when I was a Ford aficionado, I felt the same way.
Years ago, I bought a '94 Dodge Ram 3500 CTD for heavy towing, and never looked back. For me, it is Cummins all the way.


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Toy: 1999 Dodge QC LWB, Cummins, Auto, 4X4
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SidecarFlip

SE Michigan

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Posted: 03/30/19 08:44am Link  |  Quote  |  Print  |  Notify Moderator

I like them all so long as they smoke....


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Durb

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Posted: 03/30/19 08:44am Link  |  Quote  |  Print  |  Notify Moderator

Without getting too much into the weeds, where this will soon go, there are some basic differences between the layouts. Both V8 and I6 have primary and secondary balance and make fine engines. A couple of the differences are:

Cummins - Inline six has 7 main bearings and long stroke crank. Better torque characteristics but slower spin up. Cast iron head and much work can be done while still in the truck. Heavy.

Duramax - V8 has 5 main bearings and a shorter stroke crank, quicker to spin. Aluminum heads and more difficult to work on due to V configuration.

Both are good formats, It's the bolt-on stuff that makes the difference in terms of reliability. If you are buying used, there were good and bad years with both.

JIMNLIN

Oklahoma

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Posted: 03/30/19 08:51am Link  |  Quote  |  Print  |  Notify Moderator

Like a which truck is the best both are tops in that class. One isn't better than the other.
Drive them both and then you decide which one you like.
My self I prefer the white one in a crew cab 4wd.


"good judgment comes from experience, and a lot of that comes from bad judgment" ............ Will Rogers

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ib516

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Posted: 03/30/19 09:14am Link  |  Quote  |  Print  |  Notify Moderator

In anything newer than about 2013/2014 its a chocolate vs vanilla argument. They're both great, but some like one better than another.


Prev: 2010 Cougar 322QBS (junk)
02 Dodge 2500 4x4 5.9L CTD 3.55
07 Dodge 3500 4x4 SRW Mega 5.9L CTD 3.73
14 Ram 2500 4x4 Crew 6.4L Hemi 4.10
06 Chevy 1500 4x4 E-Cab 3.73 5.3L
All above are sold
Current: 07 Dodge 1500 5.7L Hemi 3.55 / 2010 Jayco 17z


azdryheat

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Posted: 03/30/19 09:43am Link  |  Quote  |  Print  |  Notify Moderator

My Duramax is quicker off the line than my friends Cummins.


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ksss

Eastern Idaho

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Posted: 03/30/19 10:11am Link  |  Quote  |  Print  |  Notify Moderator

I have owned one or more iterations of every Dmax since 01. Bought them all new, and have been happy with them (never owned a 6.7). Like already mentioned the various years have their ups and downs but overall I think both the 6.6 and 6.7 are dependable and powerful. Resale is good to great depending on the model with both of them. The resale says a lot about the confidence the market has in them, even if you plan on keeping it forever, the fact that they have value even with high miles tells you about their perceived value. The decision likely will come down to the package as a whole. It is a good position to be in.


2006 GMC 3500 CC 4X4 DRW D/A
2013 Fuzion 342
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2012 Sea Doo GTX 155
2018 Chevy 3500HD CC LB SRW 4X4 D/A
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Gulfcoast

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Posted: 03/30/19 10:23am Link  |  Quote  |  Print  |  Notify Moderator

Since I'm not racing trucks I will stick with my Cummins diesel. There's lots of them rolling across the USA every day with over a million miles on the engine.

* This post was last edited 03/30/19 10:43am by Gulfcoast *   View edit history

Halmfamily

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Posted: 03/30/19 10:34am Link  |  Quote  |  Print  |  Notify Moderator

Our 2009 Duramax has been flawless. Number 8 glowplug is the only engine issue we've had. Had to replace upper and lower control arms, tie rods and shocks. 167000 miles and going strong, hopefully another 10 years with him.


2008 GMC Sierra 3500 SLT DRW D/A 4x4 (Big All)
2006 Ford F350 PSD SRW King Ranch 4x4 (Henry) (Sold)
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2015 Forest River Sierra 360 PDEK
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