6.4 Hemi w/4.10s or Cummins?

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RamGuy110

RamGuy110

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Are you suppose to use 89 octane in the 6.4 or is that only when towing?
 

ratarmel

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Ive had 3 Ram 2500 Laramie trucks over the years.
My perspective:

#1 - '97 with 5.9B Cummins 12 valve, 3.73 rear, crew cab. Paid 32k, fuel was 99 cents per gallon. Had a cassette player too. Trans started failing at 80K miles. 16 MPG as I remember, best was 21 MPG on a long rod trip. Sold for 16K in 2016. Tighter turning radius compared to newer trucks as I recall. Louder too. Excellent truck except for the lack of 4 doors.

#2 - 2017 with 6.4 Hemi gas/3.73 rear, mega-cab. Paid 49k. Mega Cab is why I bought the Ram, I absolutely love it. Leveled/added 35" tries. Recalled 4X for minor things, plus an exhaust rattle that took 3 visits to fix. MPG was about 15 unloaded, 11 loaded/pulling. Rough ride with leaf springs unless hauling something heavy. Seats very stiff, took 1 year to loosen up. Auto-dim hi beams don't. Engine and trans had plenty of power for towing my 20' boat and 16' Util trailer loaded w/ ATVs or a tractor. The 66 trans shifted back and forth a lot when towing, even in tow haul mod (more than expected I should say). MDS was annoying, so I would put in "6" instead of "D" to bypass. Still, a great truck I sold for 45k, only b/c I wanted a diesel with 5th wheel prep. Drove it through rivers, beach sand, etc. with no problem. Interior was quite nice too.

#3 - 2021 w/ 6.7 Cummins/3.73 rear end. Mega-cab. Paid 72K(!) Coil spring rear is a much more comfortable ride, Id say twice as comfortable as my 2017's ride. MPG is 16 to 18 so far (only 3000 miles). Auto-dim hi beams better but not perfect so I don't use them. Interior definitely quieter that my 2017. DEF isn't the problem/hassle I thought it would be. Love the exhaust brake, I use it all the time. It sounds good too. The 6.7 will launch you like the 6.4 Hemi, even when towing. 68 trans shifts smoother and less frequent that the 66, b/c of the increased engine torque I guess. Really cant think of something about this truck I don't like, except the cost. Rides like a car (mostly) and pulls like a tractor. In 2017 I looked at Ford, Chevy and Ram. Mega Cab sold me on the Ram (again).
 
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RamGuy110

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So I found a new 21' 2500 Big Horn, night edition, 6.4 Hemi. It has a 4" lift and 37/13.5/20 tires. It has the tech pkg, blind spot, level 2 group, safety group, so pretty loaded for a big horn. So with those tires, it brings the gear ratio down to 3.37. With the lift, tires, etc, how much less towing capacity would you expect?
 

mtnrider

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So I found a new 21' 2500 Big Horn, night edition, 6.4 Hemi. It has a 4" lift and 37/13.5/20 tires. It has the tech pkg, blind spot, level 2 group, safety group, so pretty loaded for a big horn. So with those tires, it brings the gear ratio down to 3.37. With the lift, tires, etc, how much less towing capacity would you expect?

I wouldn't be towing at all with that to be honest. Maybe a small bass boat or something but not any serious weight. I wouldn't even tow serious weight with the diesel and 37's, that's some serious stress being put on the transmission. I know people do it all the time but I couldn't imagine doing it with a gas motor.
I'm sure it looks nice though.


.
 

retired

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Are you suppose to use 89 octane in the 6.4 or is that only when towing?
My owners manual says 87 and that is what i run. I get 12-17 mpg and when i have tried 89 or 91 i got the same.
 

sandawilliams

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The 6.4 with 8 speed tows beautifully, and unloaded driving is so much better than a Cummins (I've had 6 Cummins)

When I bought my 2021 6.4 I fully expected to install the pedal commander like I did on my 2014. After driving it now I don't experience the throttle lag that I had on the 14. No commander for me. Maybe the 4.10's help too.
 
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When I bought my 2021 6.4 I fully expected to install the pedal commander like I did on my 2014. After driving it now I don't experience the throttle lag that I had on the 14. No commander for me. Maybe the 4.10's help too.
Agreed. I have one on my Wrangler because the throttle response was abysmal, so expected to need one on the PW. Not the case. It feels plenty peppy with the stock pedal programming. If I turn off traction control, the truck will spin 35" tires off the line with ease and for a good bit.
 
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RamGuy110

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I agree! The 6.4 is stupid drivable, and easily pulls everything I need to tow with ease. Also makes an excellent in town short trip rig, without worrying about all of the diesel emissions
I may have found that I will buy tomorrow. Its a new one, 2021 Ram 2500 Big Horn, Night edition, tech package. The dealer installed a Bilsten 2" Level with Reservoir shocks, off road package, LED light package front and back and it has 20" Fuel Blitz rims on 295/60/20 Ridge Grapplers. I wish it had blind spot monitoring and 4.10s, but it has the 3.73s. The one big appealing thing is $500 reduction in car payment. I used to tow with the older 6.4 Hemis, but they had the 6-speeds. I don't remember much about them, but towing they were real sluggish.
 

NH RAM

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Ive had 3 Ram 2500 Laramie trucks over the years.
My perspective:

#1 - '97 with 5.9B Cummins 12 valve, 3.73 rear, crew cab. Paid 32k, fuel was 99 cents per gallon. Had a cassette player too. Trans started failing at 80K miles. 16 MPG as I remember, best was 21 MPG on a long rod trip. Sold for 16K in 2016. Tighter turning radius compared to newer trucks as I recall. Louder too. Excellent truck except for the lack of 4 doors.

#2 - 2017 with 6.4 Hemi gas/3.73 rear, mega-cab. Paid 49k. Mega Cab is why I bought the Ram, I absolutely love it. Leveled/added 35" tries. Recalled 4X for minor things, plus an exhaust rattle that took 3 visits to fix. MPG was about 15 unloaded, 11 loaded/pulling. Rough ride with leaf springs unless hauling something heavy. Seats very stiff, took 1 year to loosen up. Auto-dim hi beams don't. Engine and trans had plenty of power for towing my 20' boat and 16' Util trailer loaded w/ ATVs or a tractor. The 66 trans shifted back and forth a lot when towing, even in tow haul mod (more than expected I should say). MDS was annoying, so I would put in "6" instead of "D" to bypass. Still, a great truck I sold for 45k, only b/c I wanted a diesel with 5th wheel prep. Drove it through rivers, beach sand, etc. with no problem. Interior was quite nice too.

#3 - 2021 w/ 6.7 Cummins/3.73 rear end. Mega-cab. Paid 72K(!) Coil spring rear is a much more comfortable ride, Id say twice as comfortable as my 2017's ride. MPG is 16 to 18 so far (only 3000 miles). Auto-dim hi beams better but not perfect so I don't use them. Interior definitely quieter that my 2017. DEF isn't the problem/hassle I thought it would be. Love the exhaust brake, I use it all the time. It sounds good too. The 6.7 will launch you like the 6.4 Hemi, even when towing. 68 trans shifts smoother and less frequent that the 66, b/c of the increased engine torque I guess. Really cant think of something about this truck I don't like, except the cost. Rides like a car (mostly) and pulls like a tractor. In 2017 I looked at Ford, Chevy and Ram. Mega Cab sold me on the Ram (again).
2500's had coil springs on the since 2014 while 3500's stayed with leaf springs. I don't think I've ever heard anyone talk nicely about the 66rfe while towing.
Those mega cab's are nice, enjoy your '21!
 

Aelwulf

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I looked at the Lariat before ordering my Laramie. I found the interior sub-par and seemingly cheap in comparison. IMO
I very nearly got a Silverado Trail Boss with the 6.2L (yeah, gambling a bit). But the same issue there, the interior is still pretty dated and the cost difference between similar 1500s & 2500s wasn't big enough to justify it.

Aside from having a history of known folks with Ford issues when younger, I can't get over the window shape for Ford trucks. It's a non-issue for almost everyone else I'm sure but test driving one with the window down and resting my arm that drop-down drove me nuts.
 

Aelwulf

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When I bought my 2021 6.4 I fully expected to install the pedal commander like I did on my 2014. After driving it now I don't experience the throttle lag that I had on the 14. No commander for me. Maybe the 4.10's help too.
I have one on my GTI due to a small amount of drive-by-wire and turbo lag. My family got me one for the truck for my birthday. So we'll see if it's worth the difference once I figure out where I want to stash it. :/ I'll try to post up on the 'What I did this week thread'.
 

pjtj2k

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I got the 6.4 w/4.10s. Wife and I are wrapping up a 7k trip towing our TT weighing 6.5k. Truck did great the entire trip. We got between 10-11 mpg. Unloaded we're getting 17-18.
 

Frankwhoa

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Right - mileage or initial cost are not independent variables. You trade them off to see which works. My calculations concur with @General Clortho , payback for extra capital outlay for the diesel (plus finance interest) goes waaaaaay out their in usage miles. You can pay for a lot of gasoline for the much higher prices of the diesel package and finance interest.

The real question is how you intend to use - if you're pulling a heavy trailer in mountains, I wouldn't even consider gasoline regardless of axle gear ratio or transmission type. I pull a moderate weight trailer in moderate hilly country, therefore 6.4L Hemi is perfect for me. And after driving it I can validate that.
What gear ratio do you have in the 6.4 - 3.73 or 4.10? I only tow a few times a month (8k). We may get a camper later but if I have to get a deisel then, I will so we are thinking gas for now. We are very flat terrain here also
 

HEMIMANN

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What gear ratio do you have in the 6.4 - 3.73 or 4.10? I only tow a few times a month (8k). We may get a camper later but if I have to get a deisel then, I will so we are thinking gas for now. We are very flat terrain here also

3.73 which was the standard config, so most people took it or bought off dealer lot, like I did. I wanted 4.10 but wasn't willing to go thru hassle of custom order. I got a great deal on a lightly used 2500 from a lady who disliked the size. It was only a year old with 13k miles for $42K - crew cab, 4x4, short bed, Laramie (leather seats). Searched for a year before this deal popped up - pre-pandemic days, too.

I tow between a half dozen and dozen times a year, up to 7,000 lbs. 3.73 is sufficient, just not optimal. Any tow above that weight demands 4.10, up to 12,000 lbs. Any weight above that should be diesel.

I added a tuner that has a towing AFR program that opens up the fueling. Very helpful. The 66RFE trans hasn't balked at it yet, but I also removed the quick heat up thermostat from the trans oil cooler line, so it runs normal temp. That will make the trans last even with a jazzed fuel rate and 7,000 lbs. load.
 
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