Well I looked all over for information regarding pulling a 5er before pulling the trigger on a new 14 2500 CC 4x4 6.4 with 3:73s. I found very little so I thought I would post my experiences and opinions.
My background... Responsible married male with 2 married daughters and 3 grandsons. I have pulled all over with the exception of the north east and north west parts of the country. I have put hundreds of thousands of miles on an 03 2500 5.9, 05 3500 5.9 and an 08 3500 6.7. All Cummins all quad cabs and all 4x4. The 6.7 was an automatic and I ordered it. It was going to be my last truck.
Now I am no slow poke but I don't run 80 pulling either with diesel bumping $4 a gallon I really started looking at my mpg. I purchased a new 5er and we make weekend runs of 200 miles one way to the coast. My 08 was averaging around 9 mpg pulling and that is using cruise and stuck on 65 mph. The more I drove the more mad I became at low sulphur and the price and the emissions on my oil burner. So I decided it was time to let her breath only to learn that the rules had changed in the last few years regarding dpf deletes and the h&s that I wanted. I was looking at 3 grand. Again I was not thrilled.
I had been eyeing the 5.7s and just did not think it would fit my needs. I had a 5.7 charger that I put 120k on and thrashed it regularly with out issue.
My local dealer called to say there were some significant rebates on the 14 rams and I went to look. The salesman owns a 6.4 and the sales manager has one for his personal as well. So I start to look into the 6.4 as a viable replacement.
The max lifetime warranty sealed the deal. The numbers where good and I made the swap. Now I pull a 20' bay boat, a 25' walk around and Wildcat 313RE which comes in at 12k pounds and 34'. I put on full replacement bumpers my headache rack and tool box, a B&W turnover and side steps. I also added Firestone airbags and an HD compressor. I pull the 5er with a B&W companion. 90% of the time my truck is hooked up to a trailer and it is not my daily driver.
My biggest concern was power and then mpg. I took a 1200 mile round trip through the Texas hill country to southern Arkansas. I had 600 miles on the truck.
I can say that while it wasn't a Cummins the power was very good. It was very much like my 03 5.9 HO (which I loved and wish I still owned). It never struggled but did run from 3rd to 5th regularly. I never felt a shift and only heard it when she went to 3rd. I put cruise on 65 we had a quartering crosswind and lots of stop and goes in small towns. My first stretch was 200 miles and I averaged 7.4 hand calculated. My second stretch was a little over 200 and averaged 8.9 at 60 and lots of slowdowns and power up through small towns. On my return trip I wanted some wide open interstate to run. Once we hit Texas I rerouted to interstate hiway. We had quartering and headwinds of 35 mph +. I wanted to play a bit and I ran her harder. Faster starts and passing folks on back roads. I averaged 6.5 hand calculated and speed was 55-70 mph varying with traffic.
I topped off in Texarkana and set cruise on 70 running in a quartering headwind on I 30 to Dallas. Again 35 mph winds. She cruised right along in 4th at 2500 rpm and averaged 7.01 hand calculated. I ran up to 80 mph when passing. Mostly flat ground. Ounce I made the Turn and got the tail wind I bumbled to 10.3 hand calculated at 70 mph. Rpm's ran 2000 in mostly 5th gear.
Running 68 rpm's in 3rd 3000, 4th 2500 and 5th 2000. The Hemi was very quiet except for 3rd. I don't think I felt it shift the entire trip. I believe the tow/haul mode does more than knock out 6th gear and MDS. I really seamed to gear down and downshift when slowing.
2500 springs vs 3500 leafs. The springs on the 2500 definitely give a smoother ride with the exception of back to back bumps. With airbags set at 5 it would give almost a recoil like reaction. With air bags at 30 psi it was the smoothest riding rig I've ever owner trailering (not quite level and a little nose high).
Things I miss: turbo, I love hearing the turbo spoiling. Exhaust brake... No explanation needed. Constant speed. With the Cummins if I set cruise at 65 it stayed at 65... Straight up or down it didn't vary the turbo kept it right there. The hemi seems to have a 10 mph swing. If cruise is set on 65 it will run between 60 and 70 MPH.
I am very pleased with everything. I think if I was pulling anything much bigger or heavier or in mountains all the time or a full timer I would stick with an oil burner.
Things I don't miss. Running the credit card through twice to fill the tank. I ran all 87 octane as per the owners manual and gas was $2.51 to $2.69 vs $3.49-$3.79. Regen. Worrying about egr temp.
I am averaging 12.7-14 mixed driving. On a 200 mile stretch I got 14 mpg set on 70 mph.
It will be interesting to see what the next few years brings. I would think bumps in hp and torque. I would like to see what real world numbers are dynoed.
Anyway. That's my two cents for guys doing searches pondering the 6.4l Ram Hemi.