Joining the hemi crowd

[AH64ID]

Did 400 miles towing the 5th wheel this last weekend and I'm impressed with the 6.4/4.10 combo. Aside from the wife's JT and a smaller TT I haven't towed anything with a gas motor in a LONG time. The 6.4 has plenty of power, even up to 7K feet.... but it does like it's rpms. I'd guess the 5th wheel was around 9K lbs and the truck was mostly empty. I got 8.4 mpg on the way up. Last time I towed the 5th wheel up to that area the '22 got 8.8, but didn't get the last 50 miles of gradual downhill and was loaded a little heavier.

Couple positives for the Hemi, the lighter front end it very noticeable on winding mountain roads. It just seemed to want to corner faster and easier and it doesn't even have the front sway-bar installed.

The downshifting on the 66RFE when the speed is reduced with cruise control is much better than the AISIN. On the 66RFE if I take the cruise from 55 to 45 the truck will downshift on its own, the AISIN's didn't.

The engine braking is very good, at least at the GCW I was running. I went down the hill shown below (return trip) at the 90 mile mark and never touched the brakes. Cruise set to 45 and let the truck do its thing.

Then there is the NA motor at altitude drawbacks and the truck defiantly worked harder to maintain 70 at 6500' on flat ground in 75° temps, but I did expect that.

I haven't fueled up from the return trip yet, but I likely broke 10 mpg.

All in all I can't complain about the truck or how it tows. The truck certainly performed better than I did on my 55K run

 

[Deleted member 47449]

Our 2016 6 4L Hemi with the 4.10-1 in our Ram 2500 4x4 Tradesman Power Wagon when we're heading down on our home's highway 21.4 mile continuous grade (chart below) will down shift to 2nd gear when I tap the brakes more than once on the steep hairpin curves. Always does. Speed limit is 35 MPH along that stretch so holding it back in 2nd gear is fine, but then the speed limit increases on some very long straight-aways to 50 MPH on a grade of around 7% plus (10.1% for a very short stretch). Still holding it back in 2nd gear though no matter how high I rev it with giving it gas. Don't go much above 45 MPH due to the high RPMs. Only when the grade drops to below 6% will it upshift to 3rd. I've researched it and this appears normal for the 66RFE. The truck has an entirely different Mopar 66RFE since October and it's no different from the prior unit. It sure helps prevent a runaway truck. No runaway truck ramps here. So that's probably a good feature of the transmission.

Quite happy with our 2024 Ram 3500 Tradesman 4x4 HO Cummins with the Aisin due to the exhaust brake. Entirely different towing experience when going down. Going up the 6.4L starts losing power towing above 10,000 feet elevation, but not so with the 6.7L.

 

[AH64ID]

Our 2016 6 4L Hemi with the 4.10-1 in our Ram 2500 4x4 Tradesman Power Wagon when we're heading down on our home's highway 21.4 mile continuous grade (chart below) will down shift to 2nd gear when I tap the brakes more than once on the steep hairpin curves. Always does. Speed limit is 35 MPH along that stretch so holding it back in 2nd gear is fine, but then the speed limit increases on some very long straight-aways to 50 MPH on a grade of around 7% plus (10.1% for a very short stretch). Still holding it back in 2nd gear though no matter how high I rev it with giving it gas. Don't go much above 45 MPH due to the high RPMs. Only when the grade drops to below 6% will it upshift to 3rd. I've researched it and this appears normal for the 66RFE. The truck has an entirely different Mopar 66RFE since October and it's no different from the prior unit. It sure helps prevent a runaway truck. No runaway truck ramps here. So that's probably a good feature of the transmission.

Quite happy with our 2024 Ram 3500 Tradesman 4x4 HO Cummins with the Aisin due to the exhaust brake. Entirely different towing experience when going down. Going up the 6.4L starts losing power towing above 10,000 feet elevation, but not so with the 6.7L.

View attachment 86749

Defiantly didn’t have any issues with the 66RFE holding gears too long when accelerating, aside from 1st gear in TH. It seems to shift when it should. I wonder if that’s a difference with the PW and/or OE tire size programming.

The Cummins still looses power above 10,000’, which is the altitude that Cummins certifies the power rating too, but it’s definitely less noticeable.

 

[Deleted member 47449]

Defiantly didn’t have any issues with the 66RFE holding gears too long when accelerating, aside from 1st gear in TH. It seems to shift when it should. I wonder if that’s a difference with the PW and/or OE tire size programming.

The Cummins still looses power above 10,000’, which is the altitude that Cummins certifies the power rating too, but it’s definitely less noticeable.

Acccelerating on upgrades it shifts when it should. It's that our grades are quite steep going down and so it's holds back in the lower gears longer.

It's funny that Cummins certifies the power rating to 10,000 feet. We have 500 square miles with multiple dirt roads at 10,000 feet plus near our home. I wonder if it's a disclaimer.

We have two RV propane/AC refrigerators that are stated to use up to 5,500 feet on propane. Our computers are rated to 10,000 feet. Don't dare use it above that. I just installed yesterday an Orbit irrigation valve control box, Just looked online at the fine print which states a maximum altitude of 6,500 feet. I guess now that warranty is trash. Probably most of our electrical and fuel driven stuff is void due to using it at a higher altitude than recommended. 99% of the world's population lives below 8,200 feet, so it's OK.

 

[SolidAxleorBust]

66RFE gets stuck on very steep grades, revving too high. The gear spacing is terrible. My guess is with a ZF the extra gears would add a ton. That is what everyone says, its a new truck. The 66RFE is a terrible transmission.

 

[AH64ID]

Did a little internet search and the 22 is still for sale, but it transferred from the dealership in Utah to one one California.

Makes me glad I didn’t try to sell it outright. It’s been almost 3 months.

 

[Dave01]

but it does like it's rpms.

All in all I can't complain about the truck or how it tows. The truck certainly performed better than I did on my 55K run

Yes, I agree they like rpms. Just my opinion, but I think 90% of the time when someone does't like how the 6.4 tows, with either transmission, it's because they just can't get used to the high rpm revving. I ran into this some years ago with my 5.3 Tahoe. Not a great towing engine for sure, but if you wound it up it would get the job done. I find a lot of people are nervous about gas V8's and higher rpm, but these short stroke engines perform well if you let them rev higher, personally I think it is better for the engine and better for the transmission.

Was your race on trails? My wife trail runs a lot though not those distances, but we have several friends who do 25 and 50 mile trail runs pretty competetively. To me if you did the run you performed amazingly well, I can't even imagine doing that.

 

[AH64ID]

Yes, I agree they like rpms. Just my opinion, but I think 90% of the time when someone does't like how the 6.4 tows, with either transmission, it's because they just can't get used to the high rpm revving. I ran into this some years ago with my 5.3 Tahoe. Not a great towing engine for sure, but if you wound it up it would get the job done. I find a lot of people are nervous about gas V8's and higher rpm, but these short stroke engines perform well if you let them rev higher, personally I think it is better for the engine and better for the transmission.

The rpms do take some getting used to, but there is nothing wrong with them… as long as the exhaust isn’t too loud. Modern engines are built for rpms.

Let it rev how it wants and it goes great, horsepower is horsepower.

Was your race on trails? My wife trail runs a lot though not those distances, but we have several friends who do 25 and 50 mile trail runs pretty competetively. To me if you did the run you performed amazingly well, I can't even imagine doing that.

Yes it was, all trails and dirt roads. I prefer to trail run. It’s quite the endeavor. Not sure I’ll do an ultra again, the time commitment for training is ridiculous but I’m glad I’ve done them.