First RV tow with the new 2013 RAM 2500

[Cummins12V98]

Aclayton, I towed the same 5th up the I-17 Camp verde hill with the dually max tow/4:10's and I could have got up to freeway speed and more, but got behind a slow poke semi... . The transmission temps on it never went over 200. I'm curious to see how this one handles it. Engine temp was fine.

I pulled that same grade a week ago, I held 55 or more except for one spot I hit 51mph. 28K combined load with 3:42 gears.

 

[HBarlow]

The only time mine feels like it is lugging is when I forget to hit TH and EB at40 or so it will go into 6th.

Peak torque begins at 1500 rpm. Anything below that with a trailer hooked up will be lugging.

 

[Cummins12V98]

Peak torque begins at 1500 rpm. Anything below that with a trailer hooked up will be lugging.

You don't need peak torque at cruising speed on flat to hilly terrain. If it were lugging it would get better mileage on EVIC when I hit 5th on same conditions. The TH will not let it lug, it down shifts as needed. Just driving around without the TH on it will lug no question.

 

[HBarlow]

I don't know what the comment about lugging and better mileage on evic in fifth means but towing a heavy trailer at under 1500 rpm peak torque is a bad practice to be avoided.

 

[Cummins12V98]

I don't know what the comment about lugging and better mileage on evic in fifth means but towing a heavy trailer at under 1500 rpm peak torque is a bad practice to be avoided.

At 1375rpm I have about 700' # of torque so I don't think there is a problem towing in 6th on flat to hilly terrain. On the dash it shows what mileage you are getting at the moment if I shift to 5th the mileage does not go up it stays the same or was slightly better in 6th. I know the 4:10 or 3:73 would be better but the 3:42 really do perform well and I guarantee that the big boys know that, that is why they only have 3:42 available in the single rear wheel trucks.

 

[HBarlow]

I have a Cummins handbook for drivers of Cummins engines in MDTs I bought right after I bought my first Cummins. Paraphrasing, the operators manual states it is perfectly acceptable to maintain full throttle down to but never below peak torque. You may not be using full throttle but you are loading the engine at well below peak torque. It's your money, your truck, and up to you but I would never do it. When loaded with a trailer I never allow mine to run below 1600 rpm which is where peak torque occurs in cab and chassis tune.

 

[Cummins12V98]

I have a Cummins handbook for drivers of Cummins engines in MDTs I bought right after I bought my first Cummins. Paraphrasing, the operators manual states it is perfectly acceptable to maintain full throttle down to but never below peak torque. You may not be using full throttle but you are loading the engine at well below peak torque. It's your money, your truck, and up to you but I would never do it. When loaded with a trailer I never allow mine to run below 1600 rpm which is where peak torque occurs in cab and chassis tune.

I assume your manual is older than the 6. 7. With the light load I am talking about I don't see or feel a problem. You can feel when the engine is being loaded with too low of rpm. It will down shift or I will. As they say it won't hurt it's self!

On my 98 12 Valve I never ran it below 1,700 to 1750 with much of a load the temps would go up and you could feel the vibration.

 

[RVTRKN]

Sweat spot is 1900-2100 RPM and pulling heavy up a grade is 2100-2300 RPM, no matter what gear you have to be in to maintain that. I've pulled at 23K GCVW @ 2900 RPM, up the South bound Grapevine grade. Its better to run the higher RPM and keep the air flow to help in the EGT, now 2900 RPM is a little excessive, but but I didn't want to get into the truck lane at half my speed. The CTD can take that all day long, period! 1600 RPM loaded is too low and if you don't have a pyrometer to see your EGT, I will advise against it. Its nice to brag about how you never have to down shift, but melted pistons and premature turbo failures are a risk you take if you can't see the EGT.

 

[RVTRKN]

I assume your manual is older than the 6. 7. With the light load I am talking about I don't see or feel a problem. You can feel when the engine is being loaded with too low of rpm. It will down shift or I will. As they say it won't hurt it's self!

On my 98 12 Valve I never ran it below 1,700 to 1750 with much of a load the temps would go up and you could feel the vibration.

He's reading about apples and driving oranges, MDT's are a different animal than the light duty trucks we have, its all in the gearing.

 

[Cummins12V98]

He's reading about apples and driving oranges, MDT's are a different animal than the light duty trucks we have, its all in the gearing.

Mine will gear down when it needs to, that is how Chrysler made it. At that speed I have 700# torque more than enough to keep the loaf rolling along. As Stan Gozzi head West Coast warranty rep says "It can't hurt it's self".

When climbing the steepest parts of the grapevine I am in 3rd at the slowest 55mph at 2,800 rpm.

In 6th at 62 on flat to hilly ground I am not adding any excess stress. It will downshift if it needs to. I do early most of the time.

It is all about using your different gears for sure!

 

[HBarlow]

I assume your manual is older than the 6. 7. With the light load I am talking about I don't see or feel a problem. You can feel when the engine is being loaded with too low of rpm. It will down shift or I will. As they say it won't hurt it's self!

On my 98 12 Valve I never ran it below 1,700 to 1750 with much of a load the temps would go up and you could feel the vibration.

Why would that matter? The 6. 7 is based on the 5. 9 with only minor increases of bore and stroke. The basic design of the engine and operating characteristics of all 5. 9s and 6. 7s are the same.

 

[Bug Out]

I pulled that same grade a week ago, I held 55 or more except for one spot I hit 51mph. 28K combined load with 3:42 gears.

I'm looking forward to see how she pulls on this hill, especially the transmission temps which is a big concern since I consider the auto transmission to be the weak spot in the drive train, if there is one. Hopefully I'm not over 25k GCVW.



Cummins 12V98, what gear were you in at 55?

 

[Cummins12V98]

Why would that matter? The 6. 7 is based on the 5. 9 with only minor increases of bore and stroke. The basic design of the engine and operating characteristics of all 5. 9s and 6. 7s are the same.

I would assume it would matter because the newer engines are electronically controlled. No way could my 98 12V do the same thing at the same RPM as the 6. 7.

 

[Cummins12V98]

I'm looking forward to see how she pulls on this hill, especially the transmission temps which is a big concern since I consider the auto transmission to be the weak spot in the drive train, if there is one. Hopefully I'm not over 25k GCVW.

Cummins 12V98, what gear were you in at 55?

The trans is not a weak spot! Mine stays very cool on long 6%grades. You will be pleased at how well it will tow in all conditions. I was about 2,800 rpm at 55 in 3rd. It was mid 80's and trans was mid 170's. I do have a MagHytec pan and AMZ/OIL.

I left Vegas to go to Pahrump about a week ago. I drove thru town for quite a while then from there it is all uphill. When I hit the steepest part it stayed steep for a long ways. I looked at trans temp it stayed at 210 and did not move and the engine temp was 222, I was holding 2nd gear locked at 41 mph. That is the first time in 23K that it hit 2nd. I think the highway is 160 does anyone know what the steepest grade is heading to Pahrump? If I would have left 15 and climbed 160 without going thru town first I would say the trans temp would have been around 190.

 

[HBarlow]

I would assume it would matter because the newer engines are electronically controlled. No way could my 98 12V do the same thing at the same RPM as the 6. 7.

Hard parts like bore, stroke, valves, and camshaft determine where peak torque begins. Electronics can adjust boost and fueling to provide a flat torque curve to 2700 or 2900 rpm whereas 12 valves produced max torque at 1500 rpm then it sloped off very quickly.

Electronics can not create pulling torque at 1375 rpm. If you load the engine below peak torque you are probably creating harmonics and stresses that won't do an engine good over time. Decelerating through low rpm unloaded is certainly harmless and perhaps even maintaining speed with light throttle settings is acceptable. I don't even maintain speed in mine with a trailer hooked up if rpm drops below 1600 rpm.

But again, your truck, your money, your business how you choose to operate it. I would, however, suggest you ask Cummins, Inc. their opinion.

 

[AH64ID]

As much as I hate to agree with Harvey he is somewhat correct. Cummins states (even with the 6. 7) that full throttle operation under peak torque rpm should be limited to 1 minute to avoid engine damage. But he is wrong about electronics, they can and DO control the rpm at which peak torque occurs. Hard parts play a major role, but so does programming.



As for the load on the rear axle, the posted rear axle rating is driven by the tires so exceeding that will quickly get you into overloading the tires. That's not something I would want to do anywhere, let along on the scorching hot pavement in Arizona.

 

[NIsaacs]

I left Vegas to go to Pahrump about a week ago. I drove thru town for quite a while then from there it is all uphill. When I hit the steepest part it stayed steep for a long ways. I looked at trans temp it stayed at 210 and did not move and the engine temp was 222, I was holding 2nd gear locked at 41 mph. That is the first time in 23K that it hit 2nd. I think the highway is 160 does anyone know what the steepest grade is heading to Pahrump? If I would have left 15 and climbed 160 without going thru town first I would say the trans temp would have been around 190.

I wonder, in this scenario, if the engine is heating the transmission or the transmission is heating the engine? It would also be interesting, the temps you might see if you had to stop at the bottom of the steep part and resart. Does the transmission lock in 2nd after a hard unlocked condition, shifting out of 1st? What about the other gears, do they start out in unlock after an up shift, then lock or do they stay locked on every shift? If they start out unlocked then lock each time, would you sorta have 2 gears in each gear, unlock and lock?



I don't know what the grade is on Mountain Springs Summit, but it is a tough pull. The summit is 5502' and Vegas is 2181'. I pulled it with a load of wood pellets years ago in the dark, snowing like crazy about half way up. I had never been on that road so I didn't know what to expect, needless to say, I was scared... bad scared!



Nick

 

[Cummins12V98]

The truck unlocks between up shifts. Not sure about down shifts, I think it stays locked. I was surprised that it was locked in second. As far as going from 1-2 and holding 2 not sure if it will lock I have not tried it.

The treans does get warm when towing in town because it is not locked. I saw 225 driving thru Palm Springs with rv and it cooled down right away on the freeway.

I think the trans was warm going thru town in Vegas thenit was a climb right away on the freeway so the engine temp went up and probably kept the trans temp up.

Even those temps won't hurt anything. At 90 my trans temp is usually 180 or so flat land or climbing.

 

[Cummins12V98]

Hard parts like bore, stroke, valves, and camshaft determine where peak torque begins. Electronics can adjust boost and fueling to provide a flat torque curve to 2700 or 2900 rpm whereas 12 valves produced max torque at 1500 rpm then it sloped off very quickly.

Electronics can not create pulling torque at 1375 rpm. If you load the engine below peak torque you are probably creating harmonics and stresses that won't do an engine good over time. Decelerating through low rpm unloaded is certainly harmless and perhaps even maintaining speed with light throttle settings is acceptable. I don't even maintain speed in mine with a trailer hooked up if rpm drops below 1600 rpm.

But again, your truck, your money, your business how you choose to operate it. I would, however, suggest you ask Cummins, Inc. their opinion.

Harvey,

I understand what you are saying, I know by the feel and sound of the engine if I am lugging it. On flat to hilly ground it is very smooth and quiet.

As far as 12V having peak torque at 1,500 I can't even come close to towing at that low of rpm with my 98, it will growel and start overheating.

I just know by the torque curve the 6. 7 has about 700# at 1,375, I am not applying much load at that rpm on flat to hilly ground.

Anyway I appreciate your concern.

 

[Cummins12V98]

As much as I hate to agree with Harvey he is somewhat correct. Cummins states (even with the 6. 7) that full throttle operation under peak torque rpm should be limited to 1 minute to avoid engine damage. But he is wrong about electronics, they can and DO control the rpm at which peak torque occurs. Hard parts play a major role, but so does programming.

As for the load on the rear axle, the posted rear axle rating is driven by the tires so exceeding that will quickly get you into overloading the tires. That's not something I would want to do anywhere, let along on the scorching hot pavement in Arizona.

The only time I am at full throttle is above 2500rpm. It won't hold full throttle at lower rpm it just down shifts. I can see if you had a stick you could do some damage!