6.4 Hemi w/4.10s or Cummins?

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RandomRam

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6.4, 8 speed, 4.10 gears, and 35s here. I average 13.5 overall and regularly pull down 15 on the highway. It’s a great truck, drives nice, and handles a load well. More than enough power. The 8 speed auto really made a difference. The old 6 speed is pretty terrible.
 

RandomRam

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Rams 6.4 is no match for ford’s 7.3 gasser. I have to say i am a bit disappointed with my 2020 6.4 hemi‘s giddy up. If i were buying a truck tomorrow and a 7.3 gasser was available i would go that route. I do like my power wagon‘s ride but it is lacking a bit In the engine department

If you haven’t changed the tire size in the BCM you really need to. It makes a difference. Also the truck really wakes up after you get some miles on it.
 

mtnrider

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Since there have been a couple of "cost of ownership" posts let me add my real world numbers on my gas vs diesel. Both of these are mine so it's not internet numbers

At 91k miles on my current cummins I have recouped ~65% of the cost of the diesel vs what my hemi was costing me. The remaining 35% I will easily get back ++ in resale value. Now this is calculating using 85 octane gas, (85 octane and diesel are ruffly the same price where I live) if I ran the numbers using a more expensive higher octane gas that most people run in the hemi (87, 89+ ) it would be more in the diesels favor.

I realize diesel may be more in some areas but the 2 places I have lived in the past several years it was comparable to the cheap gas price so that's how I ran the numbers.

Something people don't take into consideration when saying diesel maintenance is higher. They say diesel takes more oil (12 quarts vs 7). Very true, But at 15K change intervals it is almost twice as long as the hemi so in reality it's almost 2 hemi oil changes to 1 diesel. In the end it's pretty close to a wash

The only real difference as far as maintenance is the fuel filters.

I won't get into any of the other stuff because for every broken diesel truck I can find a broken hemi truck. It happens to all makes and models

Obviously there are some variables and you can disagree all you want but these are My real numbers.


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Fatbob Frank

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My P.W. with 35s is averaging 15mpgs.
No interstate yet but my highway mileage must be pretty good to average 15 cause I start my morning everyday climbing out of the valley I live in and I know it's only getting single digits...
 

mtnrider

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My P.W. with 35s is averaging 15mpgs.
No interstate yet but my highway mileage must be pretty good to average 15 cause I start my morning everyday climbing out of the valley I live in and I know it's only getting single digits...

That is amazing mpg for a PW. Probably the best I have ever seen, especially if there are hills involved.

Have you tried hand calculating just to verify?

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Fatbob Frank

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Hand calc is slightly better cause I haven't done a speedo recalibration after going to 35s.
Prior to getting the tires installed my commute was exactly 44 miles round trip.
Now it says 43 miles.
I should add that I also added an S&B CAI and got rid of the muffler and resonator and am running a glasspack and resonator tip, but I'm thinking any mpg gains were probably offset by the bigger and heavier 35" tires.
Still I'm pretty happy cause my 1500 Laramie with 33s and 3:21 gears only averaged 18mpgs.
 

retired

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If you haven’t changed the tire size in the BCM you really need to. It makes a difference. Also the truck really wakes up after you get some miles on it.
I changed it right away with an aev snap. In fact aev used my truck to make the pro cal work with new power wagons. My speedometer and tripometer are spot on. I am at 11000 miles and will be at 12500 by tomorrow. It is a heavy truck and needs an update engine wise
 

retired

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That is amazing mpg for a PW. Probably the best I have ever seen, especially if there are hills involved.

Have you tried hand calculating just to verify?

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That is where I am at. I'm on a long trip and driving speed limits. I hand figure every fill up.started in western Montana and am in Southern Mn.
 

mtnrider

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That is where I am at. I'm on a long trip and driving speed limits. I hand figure every fill up.started in western Montana and am in Southern Mn.

I see his second post that this is a long commute mpg. I took his first post as around town type driving since he mentioned not being on the interstate so I misunderstood what he was saying.

That is a 44 mile highway commute mpg so sounds about right.

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Firebird

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Rams 6.4 is no match for ford’s 7.3 gasser. I have to say i am a bit disappointed with my 2020 6.4 hemi‘s giddy up. If i were buying a truck tomorrow and a 7.3 gasser was available i would go that route. I do like my power wagon‘s ride but it is lacking a bit In the engine department
You are probably right, I haven't driven the new 7.3 with the 10 speed, but I would imagine it is very sweet! I've had Fords, and they were excellent trucks, but for me, they just were not comfortable. I'm old now, and comfort is more important than peak power. I got tired of being achy after a long trip. Can the 7.3 pull my camper a little easier? Probably. But my 6.4 does it easily, and I am so much more comfortable in the Ram interior. Besides, the Ram also cost less, and I think it looks a little better. Just my opinion only, as there are plenty of folks who are more comfortable in a Ford or GM, it's all about what fits you the best.
 

HEMIMANN

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6.4, 8 speed, 4.10 gears, and 35s here. I average 13.5 overall and regularly pull down 15 on the highway. It’s a great truck, drives nice, and handles a load well. More than enough power. The 8 speed auto really made a difference. The old 6 speed is pretty terrible.

Don't tempt me into upgrade!!! lol Besides - I don't want to change oil on the German wonder-transmission. How ridiculous is it not to include a dipstick and oil drain? C'mon, man!
 

HEMIMANN

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Anymore you can't look at the cost you have to actually want the diesel. You will never get your money back until trade in time. I loved driving my 14 with the 6.4 with 3.73 gears and loved it ever more when I changed it to 4.44 gears. However after the trans started going and I traded it for a HO cummins I will never buy another truck with a gas engine. Just the ease of driving compared to the lack of low end grunt of the hemi makes it a much more enjoyable experience empty let alone towing. I am averaging 16 or so with 35's on my HO cummins and with my 6.4 I was averaging 12-12.5 with the same size tires.

You must pull a heavy load, then? I pull 7,000 lb max, which was too much for my half ton but just right for my 3/4 ton with 6.4L Hemi. I agree when you head north of 10,000 pounds diesel is the only choice.
 

dhay13

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Around here diesel is between .50 and 1.00/gallon more than the 89 octane. Currently 89 octane is 3.28 at my local station. Diesel is 3.89. Can't get anything any lower than 89 around here so that is the cheapest you will find. I average 12.2 hand calculated in my truck with 4.10's after about 15,000 miles of tracking it. My son just bought a 2021 2500 Cummins with 3.73's and his EVIC is reading about 15.5 after about 700 miles. He has never hand calculated but I would suspect it to be cloesr to about 15.0. Pretty much a wash as far as cost savings in fuel costs between the two. Diesel is about 19% more expensive here but gets about 22% better mileage. Very slightly more cost effective but factor in DEF and that gap narrows slightly. In my mind pretty much a wash
 

loveracing1988

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Around here diesel is between .50 and 1.00/gallon more than the 89 octane. Currently 89 octane is 3.28 at my local station. Diesel is 3.89. Can't get anything any lower than 89 around here so that is the cheapest you will find. I average 12.2 hand calculated in my truck with 4.10's after about 15,000 miles of tracking it. My son just bought a 2021 2500 Cummins with 3.73's and his EVIC is reading about 15.5 after about 700 miles. He has never hand calculated but I would suspect it to be cloesr to about 15.0. Pretty much a wash as far as cost savings in fuel costs between the two. Diesel is about 19% more expensive here but gets about 22% better mileage. Very slightly more cost effective but factor in DEF and that gap narrows slightly. In my mind pretty much a wash
Your sons truck will get better slowly for about 3000 miles and average 16-17 provided he keeps it stock.
 

loveracing1988

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You must pull a heavy load, then? I pull 7,000 lb max, which was too much for my half ton but just right for my 3/4 ton with 6.4L Hemi. I agree when you head north of 10,000 pounds diesel is the only choice.
Fully loaded my fifth wheel is just over 10k. I really didn't mind towing the same load with my 6.4 and thought it did good, until I towed it with my cummins...
 

RandomRam

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My P.W. with 35s is averaging 15mpgs.
No interstate yet but my highway mileage must be pretty good to average 15 cause I start my morning everyday climbing out of the valley I live in and I know it's only getting single digits...

In Iowa I believe it. We have too much elevation change and wind here in central Oregon. You’re either going up or down and half the time there is a steady head wind.
 

mtnrider

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Around here diesel is between .50 and 1.00/gallon more than the 89 octane. Currently 89 octane is 3.28 at my local station. Diesel is 3.89.

Crazy the price difference's around the country. Like I said in my earlier post Diesel everywhere I have lived has been the same as the cheap 85 octane gas. Right now Diesel and 85 octane is $2.89 and 87 is $3.14, 89 is $3.39 so it is cheaper for me to operate a diesel then a hemi HD truck.

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dhay13

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Crazy the price difference's around the country. Like I said in my earlier post Diesel everywhere I have lived has been the same as the cheap 85 octane gas. Right now Diesel and 85 octane is $2.89 and 87 is $3.14, 89 is $3.39 so it is cheaper for me to operate a diesel then a hemi HD truck.

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lol. yeah odd that you guys have lower octane and we don't. not sure i would run the lower stuff anyway but yeah your diesel prices are way cheaper than ours here
 

KKBB

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^^^ The cummins definitely tows better than the gas. I have always had a cummins until this truck, eventhough I didn't really need it. Well, I did have a 6.4 hemi 2014 for a bit, but traded it for a cummins because I hated towing with it. We now have a smaller 5th wheel and the 8 speed hemi tows it decent, but not like a cummins. If you have never towed with a cummins you will think the hemi is great. If you have always towed with a cummins and go to a hemi, it is a huge difference. The reason I went with a hemi and overall enjoy it more than the cummins is I have a 1 mile drive to work, and live in Iowa where 6 months out of the year can be pretty darn cold...not great for the emissions on the new diesels. Love the quick warmup of the hemi compared to the cummins.
 
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