6.4 vs 5.7

yillbs · Jan 7, 2017

Can someone explain to me the overall benefits of the 6.4 over the 5.7. I'm reading tons of reviews regarding how awesome the 6.4 is, but isn't the horsepower / torque only 10-15 points higher than the 5.7? The history isn't there, and it's really not that much more of a power house over it's smaller brother.

What gives ?

drittal · Jan 7, 2017

More power, same or better MPG. Also higher GVWR and GCWR.

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smurfs_of_war · Jan 7, 2017

Torque comes on at lower RPM.

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Farmer Fran · Jan 7, 2017

yillbs said:
Can someone explain to me the overall benefits of the 6.4 over the 5.7. I'm reading tons of reviews regarding how awesome the 6.4 is, but isn't the horsepower / torque only 10-15 points higher than the 5.7? The history isn't there, and it's really not that much more of a power house over it's smaller brother.

What gives ?

Really?

drittal · Jan 7, 2017

The 6.4 has the same power as the 5.7 hemi at 1000 rpm less

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drittal · Jan 7, 2017

Also, in the HD line the 5.7 is de-rated compared to the 1500 line. 383hp/400lbft 5.7l

vs

410hp/429lbft 6.4l

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Danno · Jan 7, 2017

Having had both a 2014 2500 5.7 and currently a 2016 2500 6.4. The 5.7 got better mpg, I would average 13-15 with a 5.7 now I'm happy to see 13 in the 6.4. Power seems about the same just comes in a little lower.

soper72 · Jan 7, 2017

I've had the 2500 with the 5.7 and now have the 6.4. I think the 6.4 feels more snappy when you have to get up and go unloaded. With a load I feel it pulls a little easier out on the highway.

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JLEONARD · Jan 8, 2017

I've had a 1500 5.7 and now a 2500 6.4. The 5.7 felt racier than the 6.4 but the 6.4 has more power seemingly slower to rev though.
I personally get the same maybe a tad better gas mileage with my 6.4 due to trying to daily driving it in MDS, or trying my best to.
I need the payload caacity, otherwise I would have kept my 1500.

HvyDuty · Jan 8, 2017

JLEONARD said:
I've had a 1500 5.7 and now a 2500 6.4. The 5.7 felt racier than the 6.4 but the 6.4 has more power seemingly slower to rev though.
I personally get the same maybe a tad better gas mileage with my 6.4 due to trying to daily driving it in MDS, or trying my best to.
I need the payload caacity, otherwise I would have kept my 1500.

I agree with this. Had a 2015 5.7 1500. The 5.7L was more rev happy and sounded better (had factory duals). The 6.4 is a work beast, a tad rougher around the edges. Can't really go wrong with either motor for stoutness with edge going to 6.4L IMO.

Wish the 8spd I had in it was in my 2500.

bcbouy · Jan 8, 2017

drittal said:
More power, same or better MPG. Also higher GVWR and GCWR.

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huh? unless the 6.4 is hundreds of pounds lighter it makes no difference to weight ratings of any truck.

drittal · Jan 8, 2017

bcbouy said:
huh? unless the 6.4 is hundreds of pounds lighter it makes no difference to weight ratings of any truck.

9k vs 10k

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SwollenMonkey16 · Feb 10, 2017

Both are great. Ppl are going to be biased to whatever they have now get over it. If you have such a problem with it just get a CTD and walk around with your feathers popped out

SHOOT2KILL · Feb 10, 2017

IMO...The weak link in the 2500 with the 6.4 is the 3.73 gear and the ****** shift points in the tranny...A 5.7 with the optional ($50.00) 4.10 gear IMO would be a better combo...The extra $1500.00 for the 6.4 isn't worth it...Remember...to utilize all 400+ hp in the 6.4 you have to spin that motor up near 6000 rpm........Which is absolute INSANITY....

drittal · Feb 10, 2017

SHOOT2KILL said:
IMO...The weak link in the 2500 with the 6.4 is the 3.73 gear and the ****** shift points in the tranny...A 5.7 with the optional ($50.00) 4.10 gear IMO would be a better combo...The extra $1500.00 for the 6.4 isn't worth it...Remember...to utilize all 400+ hp in the 6.4 you have to spin that motor up near 6000 rpm........Which is absolute INSANITY....

But you can get 4.10 in the 6.4 as well, get an extra 1,000 lbs of GVWR, and roughly the same output of the 5.7 1000rpm sooner.

Both are hamstrung by the 66rfe in the HD line.

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gustheram · Feb 10, 2017

I can't find the exact article that explains it at the moment but, if I recall correctly, the 6.4 also has some additional cooling jackets and a different coating on the valves and/or pistons for decreased wear and increased life span under heavy use conditions. Essentially, the Chrysler engineers stated that the 6.4 is a purpose-built work motor built to take a beating for 100s of thousands of miles. The 5.7 was de-rated and moved up from the 1500 line with a couple minor tweaks. The 6.4 should supposedly outlast the 5.7 under identical conditions.

yoda · Feb 10, 2017

I've said this before but in my opinion the transmission gear ratio thing is way overblown.
If it were not for the Ike Gauntlet video 99% of people would never notice the second gear ratio thing.
Could the ratios be better? yes, would it benefit from an 8 speed yes.
It was one test under specific load, grade, altitude.
In different conditions it may benefit from the steeper 2nd gear.
If the trucks were loaded differently, different grade, altitude, and none of the trucks could hold, or pull it in 3rd, The 6.4 would probably be faster than the Chev. or Ford pulling in 2nd.
If I were planning on pulling at max, in the mountains, I would no doubt have gotten the Cummins.

SHOOT2KILL · Feb 10, 2017

drittal said:
But you can get 4.10 in the 6.4 as well, get an extra 1,000 lbs of GVWR, and roughly the same output of the 5.7 1000rpm sooner.

Both are hamstrung by the 66rfe in the HD line.

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IMO... less than 20% of H.D. truck owners get close to the max gvwr at any given time....Same amount would rarely need to spin the motor to 6k to get max h.p./TQ that the 6.4 offers

For the everyday driver who needs the EGO/TESTOSTERONE trip, the 5.7/4.10 would be more than enough. Plus you keep that $1500.00 in your pocket

The roads are full of POSERS with all brands of H.D. trucks.Just look at the inside of the receiver hitchs on other trucks as you pass them on the road. Very few even have the paint wore off the inside...lol...

drittal · Feb 10, 2017

SHOOT2KILL said:
IMO... less than 20% of H.D. truck owners get close to the max gvwr at any given time....Same amount would rarely need to spin the motor to 6k to get max h.p./TQ that the 6.4 offers...

A great deal of drivers for sure don't use the full potential 98% of the time, but for that 2% you might find it handy, combined with if you need the full output of a 5.7 you can get it at 1000 less rpm with the 6.4l.

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zogg · Feb 10, 2017

I had 5.7 in a 2013 4x2 2500 to pull our 8500 pound trailer. I bought a 2016 4x4 2500 and I would have bought another 5.7 but the dealer only stocked 2500s with the 6.4. I don't notice a whole lot of difference in ride or towing, but my mpg is down about 2 mpg. I'm happy with the 6.4 but not super excited over the 5.7.....either would work for me.

6.4 vs 5.7

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