Ram 2500 4x4 Cummins-opinions

[deerefan]

Well, sorta

It seems that starting in 2013 Cummins made the throttle response painfully slow to prevent smoke and reduce re-gens. Some of the emission control is in the exhaust, some of it is in tuning, some is in combustion chamber design and some is EGR. In 2013 with the addition of DEF, they were able to go back to the 2003 and early 2004 combustion chamber design that is more efficient, then use an after treatment to keep it clean while getting better mileage than the 2012 and earlier 6.7s that held out as long as possible before going to DEF. And they tuned them to not pull very well below 1600 RPM. That's OK, but the gearing and the tranny tuning meant that the truck spends a lot of time in the 1350- 1500 RPM range, by design. This can be overcome with Tow/Haul, or blocking out 6th, but it's a pain in real world driving. Once up a bit in RPM, and given a few seconds to build boost and fuel accordingly, they pull like a locomotive. This is not about a lack of power, it's about tuning or engine manners. There have been a lot of complaints since 2013 about throttle response.

It makes no difference to me how many people complain about the Aisin. I certainly am not going to change a trans because others may complain about theirs. The Aisin is an extremely robust tranny with an incredible torque converter. A real tool for heavy work with a deep 1st gear for getting loads moving effortlessly or for four wheeling. The problem is never whether it can handle the power, it's how it shifts based on it's map that is anticipating engine torque. It is not programmable, like the 68RE, and therefore the owner must tune the engine and gearing to work with the tranny. I've been discussing tranny and tuning issues on Cummins Forum since 2003, always looking for the best compromises. If you can't get the latest 4th gens up to at least 1600 RPM while towing, they are not going to respond well and that speed is somewhere north of 70 with stock gearing and 34-35" tires. Which means poor drivability or 5th gear most of the time, or even fourth in the mountains on grades. It doesn't take a Power-Spec program to tell someone where the engine is happy as the Cummins is a very easy engine to read. 1600-2200 is the natural full range it likes. 1800-2000 is the real sweet spot for hard work. 1600 is a good all day cruising RPM with light loads. Keeping it slightly higher in its RPM range while working hard also cools it better with faster and more even coolant flow. Plus, the locomotive roar is intoxicating at about 2000 RPM.

I've addressed the issues by deleting and tuning the engine to work well with the tranny. This means better throttle response and more power, while staying within reason for cool exhaust and good shifting. Some timing and no EGR, for efficiency. Then re-gearing to 4.10 for improved drivability, more useful gears and better engine braking. It puts the RPM where it is most useful at about 1600 at 60, 1800 at 70. It never needs to run faster than 2200, but will sometimes while braking where it's puts out about 150 HP in retarding force. The result is immediate throttle response, full boost quickly and no downshifting unless I give it full throttle. It loves to pass on grades while towing. With the 3.42 gears it was annoying to drive unless 6th was locked out when towing or at high altitude in the mountains. Part of this is caused by 34.3" tires that rotate about 29 times less per miles than the stock tires.

I chose the Aisin because I had put up with a 46RH and a 48RE for 400,000 miles and was tired of their nature. During that period though, the Cummins tuning meant instant throttle response from an idle on up. The consideration was to not pull too hard or the tranny would either overheat because of it's lockup strategy, or slip the lockup clutch. But the engine was always ready to go. The Aisin is designed to hold about 50% more torque than the engine can produce stock or with mild tunes, and it runs cooler than the engine oil because of it's lockup strategy. Now, with about 150,000 on the clock on my 2014, the only tuning issue related to the tranny is getting the shift completed under load, that is where proper tuning is important. Then it will take whatever the Cummins can dish out unless your talking about cranking huge HP numbers into it. No matter how hard mine gets worked, when changing the fluid, it comes out looking fresh and red with no visible metal in suspension.

After tuning and gearing, I can lean into it from about 60 MPH and it will respond with boost and power without having to wait for it to think about it, then decide to downshift, then slowly ramp the fuel to avoid smoke. When unloaded it is very responsive and eager to go. Shifting is better because of the lower gears. And now it has 6 working gears that can all be used most of the time. Mileage seems to be unaffected and it makes no visible smoke that I can see while driving. Excellent.

That is a very accurate description of the truck’s behavior. Mine pulls fine, almost with little effort. I am still getting used to the shift flare in the 68rfe.

 

[deerefan]

I have been watching you tube about the 6.7 Cummins. One modification I came across was removing the baffle in the air intake tube just before the turbo. Has anyone here done this and what was the result? More power/mpg or nothing? The foam filter does seem unnecessary as if it disintegrates goes into the turbo, which can’t be good.

 

[TMGT]

I have been watching you tube about the 6.7 Cummins. One modification I came across was removing the baffle in the air intake tube just before the turbo. Has anyone here done this and what was the result? More power/mpg or nothing? The foam filter does seem unnecessary as if it disintegrates goes into the turbo, which can’t be good.

I did it on mine, seemed to help but its hard to tell, you can hear a bit more noise from the turbo which is fine with me. It's just there to take the noise out of the compressor side.

 

[Monster5601]

I pulled mine temporarily, heard just a bit more compressor wine but that was all. I started thinking why did the engineers' design and install this baffle, obviously, it is a costly piece. With the pressure on vehicle makers to reduce costs, there must be a good reason. I never did come across anything that described what this piece was designed to do, at least nothing athoritive. Seems that most are thinking it is there to straighten the air before entering the compressor.

I was thinking I would pull the baffle out when pulling the RV, it would be interesting to see if there was a difference when the engine is working hard and the boost was up to 35psi or better. I never did this test.

 

[TMGT]

It's for noise, the commercial truck versions of the 6.7 I've worked on don't have them. You would be amazed at how much manufacturers spend on reducing NVH for vehicles.
Apparently some people dont like the sound of a turbo and straight axhaust on a diesel............

 

[deerefan]

Just an update. Have put over 6k miles on it. Averaging 19 mpg hand calculated. Had one rough idle issue, no codes, cleared quickly. Began adding seafoam every few tanks or so. Tows well and the 4wd has been a life saver. Had to put a 10k lb pump in place on a muddy site today. Backed it in in 4 low, didn’t break a sweat.

 

[deserteagle71]

Just an update. Have put over 6k miles on it. Averaging 19 mpg hand calculated. Had one rough idle issue, no codes, cleared quickly. Began adding seafoam every few tanks or so. Tows well and the 4wd has been a life saver. Had to put a 10k lb pump in place on a muddy site today. Backed it in in 4 low, didn’t break a sweat. View attachment 586430View attachment 586431View attachment 586432

I've found the low range just as important as the 4wd, especially with an automatic transmission when backing up. Makes it so much easier on the transmission.

 

[deerefan]

I've found the low range just as important as the 4wd, especially with an automatic transmission when backing up. Makes it so much easier on the transmission.

I’ll say this, maybe it is just me, but my 97 F150 4wd and this truck were very strong in 4wd. My Chevy’s, not as much. Maybe it was gearing.

 

[RyeThomas]

Just to add for anyone with a 2013 or newer you can add a 2wd low kit so you can drive in 4wheel low without the front axle actually engaged. It is by far the best thing I have done to the truck. Backing up steep inclines with my trailers, or pulling steep slow hills is now a breeze. Gives you the power of 4 LO but in 2 wheel drive, all plug and play for under $150.

Just FYI for anyone with a Ram.

 

[BigBlue1]

Just to add for anyone with a 2013 or newer you can add a 2wd low kit so you can drive in 4wheel low without the front axle actually engaged. It is by far the best thing I have done to the truck. Backing up steep inclines with my trailers, or pulling steep slow hills is now a breeze. Gives you the power of 4 LO but in 2 wheel drive, all plug and play for under $150.

Just FYI for anyone with a Ram.

Interesting idea. I'll have to check that out for my 2017 Ram 2500.

Rob