MPGs with 6.4 Hemi and new 8-speed?

[MrMopar]

Welp...my 392 HEMI in my 2019 PW with 4.10 Gears and Crappy Goodyear 33" tires along with 4 tanks of fuel thru her is getting approx 10.5 MPG...City driving.
No trip performed yet. I'm sure it will get better.

 

[Deleted member 80]

Welp...my 392 HEMI in my 2019 PW with 4.10 Gears and Crappy Goodyear 33" tires along with 4 tanks of fuel thru her is getting approx 10.5 MPG...City driving.
No trip performed yet. I'm sure it will get better.

Sounds like you have a serious case of "Hemi-Foot"
My truck has 4.10s and does better than that, even with the 66RFE.

 

[RancidLunchmeat]

Sounds like you have a serious case of "Hemi-Foot"

That's what I was wondering! Although, 100% city driving could have something to do it. Wondering why @MrMopar had confidence that it would improve.

Maybe he knows eventually he'll get bored of the sound?

 

[MrMopar]

Sounds like you have a serious case of "Hemi-Foot"
My truck has 4.10s and does better than that, even with the 66RFE.

I do have a Hemi foot, however i do get better MPG in my Chally...but rear tires don't last long...grin

 

[RamGuy84]

So I found a Laramie black, with a 6.4, priced right and optioned the way I like, but it has the 4.10 rear end. I did order a limited diesel, but maybe regretting that now.

How would the mpg's differ from a 3.73 to a 4.10 with the 6.4L Hemi? Anybody have experience?

 

[Deleted member 80]

So I found a Laramie black, with a 6.4, priced right and optioned the way I like, but it has the 4.10 rear end. I did order a limited diesel, but maybe regretting that now.

How would the mpg's differ from a 3.73 to a 4.10 with the 6.4L Hemi? Anybody have experience?

With two overdrive gears there will be very little difference between 3.73 and 4.10. It's not the old days of 1:1 top gear, especially with the 8 speed.

 

[RamGuy84]

A little more pep with the 4.10s I would imagine as well.

 

[slimchance]

look at my fuelly in sig below for 2500 .... i can tell you this is not a town car ... without etorque stop and go kills mpg whit this trk

 

[Chriuus]

look at my fuelly in sig below for 2500 .... i can tell you this is not a town car ... without etorque stop and go kills mpg whit this trk

I have a 6.4 2500 crew cab longhorn with 4.10's and around 600 miles total. The 5 hour trip of interstate driving back from the dealership I got 16.9 the first half with MDS on and 16.3 the second half with MDS off. Driving to work (using remote start for a minute or 2 before I get in) I'm getting between 13-14. I'm hoping it'll get better once I have more miles on it.

 

[hutchman]

About 13,000 miles on mine with 3.73s. Fuelly is in my sig. I put 35" tires on about 2 tanks of fuel ago and it appears they will cost me about 1 mpg.

 

[Gondul]

I have a 6.4 2500 crew cab longhorn with 4.10's and around 600 miles total. The 5 hour trip of interstate driving back from the dealership I got 16.9 the first half with MDS on and 16.3 the second half with MDS off. Driving to work (using remote start for a minute or 2 before I get in) I'm getting between 13-14. I'm hoping it'll get better once I have more miles on it.

Was that hand calculated or the EVIC as there is usually a 1-2mpg difference (worse) than what is indicated (which is why many use Fuelly).

 

[Chriuus]

Was that hand calculated or the EVIC as there is usually a 1-2mpg difference (worse) than what is indicated (which is why many use Fuelly).

EVIC, I set the trip to hand calc rhe next fill up

 

[Gondul]

EVIC, I set the trip to hand calc rhe next fill up

Thanks... interested in seeing the spread between the two.
While some folks report it is spot on, they are generally in the minority.

 

[slimchance]

my difference between the EVIC and hand cal is all over the place, i think the fill up at topoff is driven by the gas pump sensitivity ... it seems like IF i go back to the same PUMP the spread is more constant

 

[Chriuus]

my difference between the EVIC and hand cal is all over the place, i think the fill up at topoff is driven by the gas pump sensitivity ... it seems like IF i go back to the same PUMP the spread is more constant

I forgot to mention the mpg I posted was with 87 octane. I realized it was supposed to be 89 after. So right now I'm on a mix of 87 and 89.

 

[slimchance]

my gas of choice is 88 octane E-15

 

[Gondul]

I forgot to mention the mpg I posted was with 87 octane. I realized it was supposed to be 89 after. So right now I'm on a mix of 87 and 89.

I'm just running 87... I ran 89 and 87 through the 2019 1500 and the difference in gas mileage was not enough to offset the price difference.
I'll likely run 89 when towing, but a TOP TIER 87 is likely just fine for everyday running around.

Here's a list of TOP TIER brands.

 

[Chriuus]

On the last tank I had dropped the tire pressure in the rear to 50psi and noticed around 2mpg difference watching the current mpg numbers. I noticed the evic never really wanted to get above 14 or 15 current mpg on flat stretches at 70mph. That tank was 12.6 mpg hand calc. I reset the EVIC during that cycle so I don't know what it read. I pumped the pressure back up to 65 and put 200 lbs of sand in the bed (got rid of the bounce in the rear on some stretches of interstate) and it looks like I'm getting better mpg. Now on the same flat stretches at 70mph it hits 16-18 current mpg with over 14 average.

What RPMs are you guys with the 3.73s running at 70mph? I'm right at 2000 with 4.10s in 8th gear.
Have any of you guys noticed a boost in mpg after a certain amount of miles?

 

[hutchman]

Before I put the 35" tires on my truck, the engine was turning about 1800 rpm or so at 70 mph. That's from memory though......

I run 50 psig in the fronts and 40 in the rear tires. That's what I've run from day one so I don't know how it affects my mileage, but common sense says I might get better at full pressure. I have a bad back and choose to run lower tire pressure for comfort over any savings I might get from higher pressure.

My mileage has gotten better as the truck loosened up from being new. When the truck had about 1000 miles on it, we headed to the midwest. On the way east, I got about 15.5 mpg on the highway. When we headed home, the truck had about 8,000 miles on the odometer and we got just about 16.5 on the highway. Those numbers are from my fuelly account. Right now, my overall average for 13,000 miles is 15.5. That included highway, city, and Forest Service roads. The FS roads really take a toll on mileage!

 

[Chriuus]

Before I put the 35" tires on my truck, the engine was turning about 1800 rpm or so at 70 mph. That's from memory though......

I run 50 psig in the fronts and 40 in the rear tires. That's what I've run from day one so I don't know how it affects my mileage, but common sense says I might get better at full pressure. I have a bad back and choose to run lower tire pressure for comfort over any savings I might get from higher pressure.

My mileage has gotten better as the truck loosened up from being new. When the truck had about 1000 miles on it, we headed to the midwest. On the way east, I got about 15.5 mpg on the highway. When we headed home, the truck had about 8,000 miles on the odometer and we got just about 16.5 on the highway. Those numbers are from my fuelly account. Right now, my overall average for 13,000 miles is 15.5. That included highway, city, and Forest Service roads. The FS roads really take a toll on mileage!

That seems pretty good