The 6.4 HD Hemi Thread

[hemi1282]

I havent seen mine drop under 14mpg yet i drive an hour to work over hills and all doin 60 65 and i have the mega cab, it was on 12mpg when got it with 10miles saturday i reset it before drive off and now have 1270miles gettin high 14s low 15s

 

[NewBlackDak]

104 mile round trip to the airport tonight cruise set at 66 mph(I'm not a speeder). 16.8 mpg average according to the display. I'll fill it up in the morning to confirm. Had to do a quick merge onto I-15 on the way home. Gave it about 1/3 throttle at 50mph, and it barked the rear end. After driving for only a week, it seems like the 6.4L/4.10 combo is a great match. Can't wait to put a load behind it.

The cylinder deactivation is weird when it first, but you stop noticing it fairly quickly.

 

[Jonthefireman]

All this talk about MPG....just curious. Is everyone going strictly by the EVIC, or has anyone (I'm betting Ollie has) filled her up to the brim and drove her til the "Low Fuel" came on and then done the math. IMO, that's the only true way to come up with some accurate MPG. I'm sure the EVIC is just a "ballpark" number. I gave up on the EVIC when I quickly realized that I was NEVER going to get the tire pressure to read a perfect 65 up front and 80 in the back like the door said. So to put faith in accurate MPG, no way.

Besides, it's a 6.4 HEMI....did we actually expect anything better than 15 maybe? JMO

 

[Jonthefireman]

On another note.....I've been toying with doing a little exhaust mod already. I stopped by the local hot rod muffler shop and he suggested to just go with a Magnaflow 3.5" muffler replacement rather than duals. Said it would breath better and give it a better sound.

My only worry is the "sound" when the MDS kicks on. I actually bought a programmer to turn off the MDS on my 5.7 just because the MDS sounded horrible with duals.

Has anyone already done anything with their 6.4? Thoughts??

 

[NewBlackDak]

All this talk about MPG....just curious. Is everyone going strictly by the EVIC, or has anyone (I'm betting Ollie has) filled her up to the brim and drove her til the "Low Fuel" came on and then done the math. IMO, that's the only true way to come up with some accurate MPG. I'm sure the EVIC is just a "ballpark" number. I gave up on the EVIC when I quickly realized that I was NEVER going to get the tire pressure to read a perfect 65 up front and 80 in the back like the door said. So to put faith in accurate MPG, no way.

Besides, it's a 6.4 HEMI....did we actually expect anything better than 15 maybe? JMO

This is obviously not for a full tank....
I filled up last night before heading to the airport to pick up a family member, and reset the computer just after I started the truck. The readout said 16.8 for the trip. It was mostly CC set at 66, but a couple romps to merge or get around someone and 3-4 mins idling while loading bags/hi/hugs.
I just filled up at the same pump, and put in 6.289 gallons with the trip meter reading 105.2. That makes 16.72761965336301 not exactly the 16.8 the truck says, but close enough for me to trust it.

I'll create a profile on fuelly when I get home, so I can confirm the EVIC from time to time, and have a long term history for it.


Sent from my iPhone using Tapatalk

 

[NewBlackDak]

On another note.....I've been toying with doing a little exhaust mod already. I stopped by the local hot rod muffler shop and he suggested to just go with a Magnaflow 3.5" muffler replacement rather than duals. Said it would breath better and give it a better sound.

My only worry is the "sound" when the MDS kicks on. I actually bought a programmer to turn off the MDS on my 5.7 just because the MDS sounded horrible with duals.

Has anyone already done anything with their 6.4? Thoughts??

In the 1500, you can manually put the truck in the top gear instead of "D" to deactivate MDS. Have you tried that?


Sent from my iPhone using Tapatalk

 

[Olli]

All this talk about MPG....just curious. Is everyone going strictly by the EVIC, or has anyone (I'm betting Ollie has) filled her up to the brim and drove her til the "Low Fuel" came on and then done the math. IMO, that's the only true way to come up with some accurate MPG. I'm sure the EVIC is just a "ballpark" number. I gave up on the EVIC when I quickly realized that I was NEVER going to get the tire pressure to read a perfect 65 up front and 80 in the back like the door said. So to put faith in accurate MPG, no way.

Besides, it's a 6.4 HEMI....did we actually expect anything better than 15 maybe? JMO

Not yet. My truck is supposed to be built this week!

Olli

 

[Olli]

I was "in paint" yesterday! I should see the truck in a few weeks.

Olli

 

[FF in MN]

Took the plunge and ordered today! 2500 CC Longhorn 6.4...now I play the waiting game...and the deciding which mods I want/can afford game.

 

[Olli]

The waiting game isn't too long..

I ordered 1/31. Today is 2/20 and my truck is "in shipment". I am guessing that I should take delivery the week of 3/9. That would be only 6 weeks!

Olli

 

[pullthis]

anyone have any idea what the bore and stroke is for the 6.4?
just wondering what combination they used to get to 390+ci.

 

[Olli]

4.09" x 3.72"

Olli

 

[pullthis]

thanks olli
I was wondering if they used the same bore and stoke as the srt motor.
so does it have the apache heads?
what is the compression ratio?
does it have the log type exhaust manifolds?

 

[Olli]

This is all that I have.....there is more information on allpar.com

ENGINE: 6.4-LITER HEMI® V-8
Type and Description Eight-cylinder, 90-degree V-type, liquid-cooled, with variable-valve timing (VVT)
Displacement 392 cu. in. (6,417 cu. cm)
Bore x Stroke 4.09 x 3.72 (103.9 x 94.6)
Valve System VVT, push-rod operated overhead valves (16, two-per-cylinder), eight de-activating
and eight hydraulic lifters all with roller followers
Fuel Injection Sequential, multiport, electronic, returnless
Construction Deep-skirt cast-iron block with cross-bolted main bear caps, 356 aluminum cylinder
heads with hemispherical combustion chambers
Compression Ratio 10.0:1
Power (SAE gross) 410 hp (306 kW) @ 5,600 rpm
Torque (SAE gross) 429 lb.-ft. (582 N•m) at 4,000 rpm
Maximum Engine Speed 5,800 rpm limited
Fuel Requirement Unleaded regular, 87 octane (R+M)/2
Oil Capacity 7.0 qt. (6.6 liters)
Coolant Capacity 15.75 liters
Emission Control Three-way catalytic converters, heated oxygen sensors, cooled electronic EGR and
individual cylinder fuel control

 

[pullthis]

thought I saw egr piping headed for the intake. To bad it has to eat exhaust to meet emissions.

 

[PTCTreeGuy]

Having been around and driven all 2500s my whole life I was surprised I didn't even really consider replacing my 2500 Suburban with a 3/4 ton. I had been almost exclusively caught up in the EcoDiesel and its 28-30 mpg estimates on the highway since I commute almost 100 miles a day to work. It's labored roll-out and seemingly decreasing interest from my local dealers to even talk about it has me considering the options.

I know going from that high mpg engine to the 6.4 is a wide swing but if I'm going to go with a Hemi I want to see what the gap between the 5.7 1500 and 6.4 2500. Yes I would pay the extra for the 6.4 but not going up to the Cummins, no need for the extra torque for the 7k bucks. It seems like most of you are getting around 15 to highs of 17ish in the 6.4 vs 17-19 and so seemingly high claims of 22+ with the 5.7 1500, if that sounds about right? I know neither one is an efficiency champ but just gathering all information I can and to pick the right truck. Or if Ram and the dealers keep ticking me off know what they have vs the competition.

Thanks for any information, looking at the Outdoorsman trim in both models.

 

[Donelam304]

Sure, you can get the higher milage in places where it's flat but even the guys I work with that have the ½ ton and ¾ ton 5.7 HEMI's are getting almost what I get on my 6.4L. I have just over 4,200 miles in mine now in right at 2 months and I'm up to about 11.9mpg now. But in flatter terrain I can get 15mpg pretty easy.

Sent from my Samsung Galaxy Note 3 (SM-N900V) via taptalk...

 

[PTCTreeGuy]

It's fairly flat here commuting around Atlanta, sadly 15 mpg isn't much better than my old 95 Suburban but kids on bicycles wouldn't be taking me from a light anymore. And runs regular, the Burban can't handle regular anymore; about shakes itself to pieces on anything but premium.

 

[Donelam304]

O e of the guys here on base that has an SRT 8 (that he will only drive in the summer and is 0% chance of rain). Lol. Said when he puts his programmer on eco mode he gets 18mog to 20mpg. I'm not sure if it's true. But just going off what he said. I dunno if our motor will do the same with a better exhaust and CAI. Diablo just released two tuners for the 6.4L and k&n has an air filter and tube for it. But no hood yet or CAI.

Sent from my Samsung Galaxy Note 3 (SM-N900V) via taptalk...

 

[FF in MN]

I've got a few more hours to edit my order...do I need dual alternators? I have it in the order now, but trying to trim costs if I can. Truck will be a DD mostly and pulling a travel trailer 7-10 weekends a season.

How about the anti-spin differential? Yes/no?

Ctr Stop Lamp w/cargo camera? Yes/no?

Thoughts? Thanks fellas!