Ram 6.4, 4.56 MPG

[Bucksaw]

OK, I know what you are thinking. "Why do you buy a 3/4 ton truck for mileage?" "If you want mileage, buy a Prius." "Blah, blah, blah." And, yes, you are right. I didnt buy it for mileage, I dont want to buy a diesel, and I am not going back to stock. Anyway, I think that about covers the basic smart-A responses to the question I am about to ask.

Also, I have scoured the Ram forums looking for an answer, but everything is either being reported as mileage while towing, pertaining to 4.10 gears, or for 37" tires. Cant find my exact setup.

So, I have this 2500 pickup with a 6.4 Hemi, 35" tires, a skirted flatbed, and factory 3.73 gears. I love the truck more than any one I have had to date, and I have had a lot. The only complaint I have is that when I put the 35s on it, while it looks awesome, it has a bit of a lug in 6th gear at speeds between 60 and 70, which is where I drive most of the time. The mileage I can live with, but I would like to get a little more "umph" to it to be able to hold 70 a little easier in 6th gear. So, I have considered having it regeared to 4.56 gears after I pay it off. My thoughts are that if I put lower gears in it, it should be able to handle itself better on the highway and allow the MDS to kick in at highway speeds, which at the very least might help offset the higher RPMs that I will be turning. Plus, the added capability when towing would be a big plus.

While I am OK if the mileage stays the same, I dont want it to get any worse. Anyone have any personal experience with the 6.4 Hemi matched to 4.56 gears that can report on before and after mileage?

[jshouse]

Mirrors up or down?

[Spearchunker]

Mirrors up or down?

winner lol

[txwhitetail]

Break the mirrors off and an instant gain of 4 mpg.

[denimdeerslayer]

Mirrors up or down?

Mirrors are always deployed!!!!

[scott123456789]

If you research power wagon numbers it should give you a little better idea?

[duckmanep]

and that ghost trailer must be HEAVY!!!

[Tyrex750]

When u put bigger tires, if u want it back to stock ratio that's the only way is to change out the gears. Putting bigger gears the motor can turn the bigger tires easier which puts u back like it has stock tires.

[Bucksaw]

Mirrors up or down?

winner lol

Break the mirrors off and an instant gain of 4 mpg.

Mirrors are always deployed!!!!

Mine are always down. Aint searchin' for any company.

[Bucksaw]

If you research power wagon numbers it should give you a little better idea?

Power wagons have 33" tires and 4.10 gears. The old ones had 4.56 gears, but the 5.7 hemi. The setup Im looking for is for a 6.4 hemi with 35" on 4.56.

[Bucksaw]

When u put bigger tires, if u want it back to stock ratio that's the only way is to change out the gears. Putting bigger gears the motor can turn the bigger tires easier which puts u back like it has stock tires.

Numerically, it works out to needing 3.80 something gears, so just going by the numbers, 4.10s would be the closest upgrade. However, there are many other variables that can come into play that dont always make the numerical calculations accurate.

[batmaninja]

Have you tried some truck nutz?

Seriously though, I put a CAI and a chip on a 5.7 Hemi and it really woke it up.

[beefiedoubleoh]

Lower gearing = less MPG. There's no way around it.

[Acameron52]

Mirrors up or down?

Good question.

[pblaetz]

What rpm's are you running in 6th gear at 70mph and what rpm's in 5th gear at 70?