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Old 12-27-2013, 08:35 AM   #29
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Originally Posted by onechaddude View Post
It might be at the peak torque of the engine but that does not mean it is geared low enough. My brother has 2012 d/a 2500 and I rode with him pulling a 24' enclosed trailer with 4 wheelers in it and every hill we hit it changed to 5th gear and some to 4th gear. I was not very impressed with it and can only imagine how it does with 5th wheel toy hauler. I would have thought it would pull much better with 765 #/ft torque but I guess 3.73 is just a little to low for the 6th best overdrive.
I pull exact same trailer with same load in it with my 2011 ram Cummins 2500 with only 650 torque and rarely does it come out 6th gear with cruise on the hills and one mtn we climb in VA the d/a has to run 4th gear at 3200 rpm to run 70 mph up it and my ram climbs it in 5th gear at 2450 rpm. After riding with him I thought it was a good thing that truck had a good tranny as often as it changes gears. Otherwise seems like a nice truck and engine just didn't pull as expected.
Chad
One thing to remember is that the downshifts are programmed by the calibrators. The downshifts or no downshifts may not have anything to with the power of the engine but is because the calibrators programmed the shift strategies that way. It may have to do with emission controls under certain loads or in anticipation of an increased load on the powertrain and the engine is at the correct RPM for that anticipation. If your Cummins had to shift into 4th gear on that downshift what are the possibilities that you would be higher than the engine speed limits? Your at 2450 in 5th gear but isn't RPM limit under 3K for that engine? 4th gear may cause the engine to over rev while the Duramax is happy at that RPM. In line 6 cylinders do have an impressive low end torque band that many V engines typically do not have.

http://cumminsengines.com/cummins-tu...2013?#overview

http://www.duramaxdieselspecs.com/lml.html

The Duramax has a higher RPM band than the Cummins appears to have.
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Old 12-27-2013, 11:06 AM   #30
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I learned with my '03 GMC 8.1 to tow my 5th wheel using cruise control. The computer does a much better job of calibrating throttle position and shifting than I can. It's my first truck with the "drive by wire" throttle pedal and doesn't have the same feel as my older 1 ton does. I've thought about putting in 4.10 gears to gain more torque but it does pretty well,, I realize it will never be a Duramax...
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Old 12-27-2013, 07:53 PM   #31
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One thing to remember is that the downshifts are programmed by the calibrators. The downshifts or no downshifts may not have anything to with the power of the engine but is because the calibrators programmed the shift strategies that way. It may have to do with emission controls under certain loads or in anticipation of an increased load on the powertrain and the engine is at the correct RPM for that anticipation. If your Cummins had to shift into 4th gear on that downshift what are the possibilities that you would be higher than the engine speed limits? Your at 2450 in 5th gear but isn't RPM limit under 3K for that engine? 4th gear may cause the engine to over rev while the Duramax is happy at that RPM. In line 6 cylinders do have an impressive low end torque band that many V engines typically do not have.

http://cumminsengines.com/cummins-tu...2013?#overview

http://www.duramaxdieselspecs.com/lml.html

The Duramax has a higher RPM band than the Cummins appears to have.
James
The Cummins is rated the same as duramax which is 3300 rpm and I have run it at that on steeper hills no problem. Also have turned over that downhill with exhaust brake on on steeper hills. I am by no means an expert on diesels but this is just what I have seen in riding in both trucks. I'm definitely not against the Chevy d/a as I was huge Chevy man before I started driving dodge a few years ago. I also tried to trade for Chevy d/a before the last couple of dodge trucks but cost quite a bit more that I couldn't seem to pay. Other than frequent shifting his truck seemed to handle the trailer fine getting up to speed and controlling the load. I believe his Chevy is slightly better riding empty but my ram seems to not buck as bad with heavy tongue weight. Maybe that's due to lighter springs on rear? Either way I think all 3 are well built trucks if we could just afford the darn things, they really are getting high.
chad
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Old 12-27-2013, 09:20 PM   #32
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Thanks for that correction then. I was just going by that data on the Cummins site where it stated 3K for the fuel cut off. But it can definitely be a misprint. I've driven a few Duramax but not when towing. The power seemed more in the higher RPM band but again that was with no load. Been meaning to test drive a new Ram to compare the "feeling" to the others. But towing is really what all 3 diesels are designed for.
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Old 12-28-2013, 07:03 AM   #33
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Thanks for that correction then. I was just going by that data on the Cummins site where it stated 3K for the fuel cut off. But it can definitely be a misprint. I've driven a few Duramax but not when towing. The power seemed more in the higher RPM band but again that was with no load. Been meaning to test drive a new Ram to compare the "feeling" to the others. But towing is really what all 3 diesels are designed for.
James
You may have read the Cummins site correctly as there are different versions of the same engine. I have an 07 HR Neptune that has a 5.9 ISB Cummins with exact power ratings as that year dodge truck but it is governed to 2600 rpm. Not sure what the difference is, probably just in the computer programming for each engine. I have turned the Rv engine over 2600 though using exhaust brake.
Chad
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Old 01-02-2014, 07:26 PM   #34
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So - did you find something you like?
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