We are going from diesel back to gasser and I will stick with a Ram 2500. We tow all over the West which, of course, means lots of mountains to climb so I would like the power and payload of the 6.4. On the other hand, the truck will be my daily driver so I would lean toward the 5.7 for mpg. As I shop, research, and listen to others, I am realizing the best of each engine, BUT I am not hearing from others that tow in the mountains.I would appreciate hearing from those who tow with either engine, in the 2500. Please don't turn this into a brand war.Thanks in advance and Happy New Year!

I went from a history of two cummins diesels to the 6.4L Hemi.Mountain towing is not a problem with this engine. The rv I tow is a 37' 5th wheel that has 3 slides and weighs about 11000 to 11500#, depending on how much we pack. I live in the flat lands but always tow to the rockies. In the flats, we fight headwind. In the mountains we climb and descend grades.The 6.4L Hemi and previous 5.9L Cummins both climb the same grades at about the same speeds. The difference is that the Cummins did it in 3rd (4 speed auto) at about 2200 - 2400 RPM, and the 6.4L Hemi uses 2nd gear (6 speed auto) at ~5000 RPM.Towing mpg with the Cummins was 10-12, and the Hemi gets 7-9 mpg hauling the same RV over the same route. The diesel had 3.73 gears, the Hemi has 4.10s.On the mpg front, an important thing to note is that the 6.4L Hemi is able to switch into 4 cylinder mode when running empty, the 5.7L in the 2500 doesn't have that ability as it is not equipped with MDS. RAM engineers say the 6.4L Hemi will therefore get better mpg than the 5.7L (Video).Also, the 6.4L hemi has only slightly more power than the 5.7L, but it makes peak torque 800 - 1000 RPM lower than the 5.7L, GMs 6.0L Vortec, and the Ford 6.2L gas V8. That is what allows MDS to be used, and is great for towing. They accomplish this by using variable length intake runners. Good low end, then they change to add more top end power. If you listen carefully you can hear it happen when you floor it and the rpm climbs.Typically, my truck will haul my RV at 2200 RPM in 5th gear and hold there down the highway when in flat terrain. Here's a video of my truck towing my RV. Link

Let me know if you have any other questions.I forgot, I have a few other truck videos on YouTube I can link if you want.

I have a 2014 1500 with the 5.7 which works well for my particular needs, but if I required a 2500 it would be powered by the 6.4 simply because of the RPM power range. You will read of the recommendation for 89 octane fuel for the 5.7 but in reality you will notice very little if any difference in actual driving. Towing, both engines will provide average mpg of around 8 to 10 depending on trailer size. Empty both will average 16 to 18. We drove our 5.7 1200 miles over Christmas,from south of Memphis to Charleston SC to Raleigh NC and back through the Smokies. No towing and mostly highway speeds in mid 70's. Average fuel burn was calculated at 19.8. With 87 fuel. If your towing requirements are within the range of the 5.7 specs, you will be very happy with it. If you need. A little more torque, get the 6.4. You will certainly be happy with either.

Why does RAM offer both 5.7 and 6.4 engines in their HD trucks? Must be a reason.

FishOnOne wrote:Why does RAM offer both 5.7 and 6.4 engines in their HD trucks? Must be a reason.Because they don't have a 2.7 eco turbo ?

Towing with Ram 2500, either 5.7 or 6.4 engine | Good Sam Community

24 Replies

otrfun
Explorer II
Jan 02, 2015
otrfun wrote:
It's important to keep in mind the Ram 2500 5.7 has 900-1000 lbs. LESS payload than the same Ram 2500 with a 6.4. Many will argue this is just on paper since the rear GAWR is the same for the 5.7 & 6.4 (fwiw, GVWR is exactly 1000 lbs. less for the 5.7--confusing to say the least). Regardless, that's a BIG deal if you tow.

If you tow, and factor in the fact the 6.4 has MDS (better MPG), more torque/hp, and almost a 1000 lbs. more payload, IMO $1300-$1400 is a small price to pay for all this capability.

Good luck and Happy New Years!
APT wrote:
Ram 6.4L doesn't have 900 pounds lower payload than 5.7L. Diesel does.
The 6.4 has ~900 lbs. more payload than the 5.7 and the CTD. Or, put another way, the 5.7 and CTD have almost the same payload.

.
Community Alumni
Jan 02, 2015
camp-n-family wrote:
...Not sure why the 5.7 doesn't have it since it is available in the 1500 series.

I believe this was due to the additional weight of the 2500 and the type of service it was designed for. The truck would constantly hop in and out of MDS with a 5.7L.
APT
Explorer
Jan 02, 2015
Ram 6.4L doesn't have 900 pounds lower payload than 5.7L. Diesel does.

Get the 6.4L. There won't be any measurable fuel consumption difference, but you'll always feel the power. That includes more power in 4-cyl mode too.
gtsum
Explorer
Jan 02, 2015
I had a 2013 ram 1500 with 5.7 and used it to tow atvs and trailers to and from the west va mountains...I cant imagine using the 5.7 hemi in a 2500 towing heavy loads. Yes it has power (above 4000 rpms), but the mileage towing is terrible (I got about 11.5 on 700 mile round trips towing 4000lbs). My 2013 5.7 DID have the MDS also (could get 19 hwy and about 14-15 city over 20k miles that I owned it).
Hannibal
Explorer
Jan 01, 2015
I went from four Cummins Rams to a 5.7L Hemi powered 2500HD in 2005. I was very happy with the 5.7L around the southeast towing 10,400~lbs weighed 5th wheel. However, if given the choice, I would pay the $1500 for the 6.4L option without hesitation. Especially if I lived out west.
spoon059
Explorer II
Jan 01, 2015
FishOnOne wrote:
The reason I asked is there's either a market for each engine to justify having two gas engines or perhaps RAM still has some commitment to continue producing the 5.7. For me the 6.4 just seams to be a better engine so why not standardize on one to simplify the manufacturing line at the truck plant.

The Ram 1500 uses the 5.7 and they have to worry about EPA mileage in the half ton trucks. They already have the engine... why not offer it?

My Tundra with the 5.7 has slightly less power and handles my needs perfectly. When the family grows and I need more payload, the Ram 2500 with the 5.7 would be a perfect vehicle. No real mountains on the east coast to worry about...

OP, glad you made a decision. For $1500 more, I think its a great and easy decision to upgrade to the 6.4. Enjoy it and put the miles on!
IDman
Explorer
Jan 01, 2015
Thanks to you all for your comments and opinions. Contrary to what a couple of you said, around here the dealers have mainly 6.4s, and 5.7s are rare in 2500. That should tell me something about towing in the mountains!

I'm going with the 6.4!

Thanks again!
RoyJ
Explorer
Jan 01, 2015
otrfun wrote:
It's important to keep in mind the Ram 2500 5.7 has 900-1000 lbs. less payload than the same Ram 2500 with a 6.4. Many will argue this is just on paper since the rear GAWR is the same for the 5.7 & 6.4 (fwiw, GVWR is exactly 1000 lbs. less for the 5.7--confusing to say the least). Regardless, that's a BIG deal if you tow.

If you tow, and factor in the fact the 6.4 has MDS (better MPG), more torque/hp, and almost a 1000 lbs. more payload, IMO $1300-$1400 is a small price to pay for all this capability.

Good luck and Happy New Years!

This makes me wonder if the payload is another "marketing spec" vs real "engineering spec".

If the GAWRs are the same, and we know the same frame and drivetrain (save for the engine obviously) is used, how can there be any difference? Softer sprung? Lesser brakes? But, those would be reflected in the GAWRs, as springs and brakes are part of the axle spec.

It's definitely not power limited, as both engines can tow 10,000+ lbs, so an extra 1000 lbs payload won't even be felt by the engines.

This is why I always say, with a bit of research, we can safely ignore SOME manufacturer's specs.
camp-n-family
Explorer
Jan 01, 2015
On the mpg front, an important thing to note is that the 6.4L Hemi is able to switch into 4 cylinder mode when running empty, the 5.7L in the 2500 doesn't have that ability as it is not equipped with MDS. RAM engineers say the 6.4L Hemi will therefore get better mpg than the 5.7L (Video).

X2 Everything I've seen has the 6.4 getting better gas mileage than the 5.7. I imagine mostly due to MDS. Not sure why the 5.7 doesn't have it since it is available in the 1500 series.

Overall, the 6.4 seems to be the better buy. That being said, they are still pretty new and hard to find on dealer lots. I couldn't wait the time it would take to order one so I ended up with a slightly used 2500 with the 5.7. Haven't towed with it yet but it has the same power as my outgoing Tundra which hauled my 8k tt just fine. Mileage is worse, averaging 14mpg, but then it curbs 1k more than the Tundra.
ib516
Explorer II
Jan 01, 2015
06Fargo wrote:
ib516 wrote:
Let me know if you have any other questions.

I forgot, I have a few other truck videos on YouTube I can link if you want.

Hi ib516 - how does your empty pickup winter mpg compare between your last diesel and your new truck?

I'm getting about 15% less mpg with the Hemi in the winter when compared to the 5.9L Cummins. However, regular unleaded has been averaging about 25% less expensive than diesel here so I'm happy. Having heat (and heated seats & steering wheel) has been nice too.

Summer commuting nets a bigger advantage for the diesel.