The 6.4 HD Hemi Thread

[Canadian Mopar]

Currently looking for a new truck to replace my 2011 Ram 2500 with a 5.7L HEMI. I've been looking at used 6.4L trucks and think I'm pretty set on one (or at least another gas HD RAM) as my 5.7L does an ok job for what I need it for and I can't justify the cost/pain of a Cummins with the price of diesel now. Only problem I'm having is 6.4L's are harder to find around here (and 6.4L's with 4.10's are even worse). So wondering if a 6.4L and/or 4.10's make that much of a difference from a 5.7L with 3.73's?
I use my truck mostly for towing/hauling (usually a ~5500# enclosed trailer or ~2300lb payload), where most of the towing/hauling is done through the mountains (4-6hr trips). My 5.7L isn't terrible in the mountains with the 3.73's, it just hardly ever shifts up to 5th and works pretty hard on the long uphill sections, so I'm wondering if the 6.4L (and the 6 speed) would be any different?
I've also been reading a few guys were re-gearing their gas HDs to better match the transmission gears, is that something I should seriously be looking at? And don't worry about 3.73/4.10's right off the bat? I never plan on lifting my truck or going bigger than the stock ~33" tire.
Thanks!

 

[sandawilliams]

Currently looking for a new truck to replace my 2011 Ram 2500 with a 5.7L HEMI. I've been looking at used 6.4L trucks and think I'm pretty set on one (or at least another gas HD RAM) as my 5.7L does an ok job for what I need it for and I can't justify the cost/pain of a Cummins with the price of diesel now. Only problem I'm having is 6.4L's are harder to find around here (and 6.4L's with 4.10's are even worse). So wondering if a 6.4L and/or 4.10's make that much of a difference from a 5.7L with 3.73's?
I use my truck mostly for towing/hauling (usually a ~5500# enclosed trailer or ~2300lb payload), where most of the towing/hauling is done through the mountains (4-6hr trips). My 5.7L isn't terrible in the mountains with the 3.73's, it just hardly ever shifts up to 5th and works pretty hard on the long uphill sections, so I'm wondering if the 6.4L (and the 6 speed) would be any different?
I've also been reading a few guys were re-gearing their gas HDs to better match the transmission gears, is that something I should seriously be looking at? And don't worry about 3.73/4.10's right off the bat? I never plan on lifting my truck or going bigger than the stock ~33" tire.
Thanks!

With your light load 3.73's are just fine. I tow 8800 lbs with another 1500 in the bed. 50,000 miles over all terrain with no problem at all.

 

[Mountaineer83]

Currently looking for a new truck to replace my 2011 Ram 2500 with a 5.7L HEMI. I've been looking at used 6.4L trucks and think I'm pretty set on one (or at least another gas HD RAM) as my 5.7L does an ok job for what I need it for and I can't justify the cost/pain of a Cummins with the price of diesel now. Only problem I'm having is 6.4L's are harder to find around here (and 6.4L's with 4.10's are even worse). So wondering if a 6.4L and/or 4.10's make that much of a difference from a 5.7L with 3.73's?
I use my truck mostly for towing/hauling (usually a ~5500# enclosed trailer or ~2300lb payload), where most of the towing/hauling is done through the mountains (4-6hr trips). My 5.7L isn't terrible in the mountains with the 3.73's, it just hardly ever shifts up to 5th and works pretty hard on the long uphill sections, so I'm wondering if the 6.4L (and the 6 speed) would be any different?
I've also been reading a few guys were re-gearing their gas HDs to better match the transmission gears, is that something I should seriously be looking at? And don't worry about 3.73/4.10's right off the bat? I never plan on lifting my truck or going bigger than the stock ~33" tire.
Thanks!

The biggest difference in the 3.73 and 4.10 gear set is the towing capacity. The 4.10 had a higher rated towing. As for the 5.7 vs the 6.4, the numbers (hp and tq) aren't that far apart, but the torque curve on the 6.4 is lower, so it doesn't work as hard (i.e., lower rpm on the 6.4) as a 5.7 would under the same load.

As for the loads you mention, a 3.73 geared 6.4 will do just fine. But if you can find one with 4.10, then it's better to have more and not need it than to need it and not have it.

 

[Canadian Mopar]

With your light load 3.73's are just fine. I tow 8800 lbs with another 1500 in the bed. 50,000 miles over all terrain with no problem at all.

The biggest difference in the 3.73 and 4.10 gear set is the towing capacity. The 4.10 had a higher rated towing. As for the 5.7 vs the 6.4, the numbers (hp and tq) aren't that far apart, but the torque curve on the 6.4 is lower, so it doesn't work as hard (i.e., lower rpm on the 6.4) as a 5.7 would under the same load.

As for the loads you mention, a 3.73 geared 6.4 will do just fine. But if you can find one with 4.10, then it's better to have more and not need it than to need it and not have it.

Alright, thanks! Good to know.

 

[MN-Ram]

I swapped out the factory shocks yesterday, and threw in some Bilstein 5100’s.

I’m not gonna lie, the front shocks were mother effers to get out. But the back 2 were easy.

Just my little drive around the block (with a lot of potholes) last night showed remarkable improvement over the factory shocks.

 

[Marine Les]

The truck I want is the 6.4 with the 8 speed and 3.73 gears and that combo would suit your needs perfectly but there are no used ones as they are just now arriving at dealers.

 

[Moto006]

Hi guys, the Wife and I got the camper and pulled it back to PA from Michigan. Added a Magnaflow exhaust, a CAI and Airlift stabilizer bags to the beast since I bought it. Truck pulled the load like a champ but the highway was mostly flat. So far, so good. If I have any complaints it would be the fuel mileage was shocking at 5.5, was hoping for a little better but with only 4k on the odometer maybe it will get a little better or just wishful thinking. lol Going to put her to the test this summer in the rockies with camper in tow, can't wait to see the mileage going up those mountains!!

 

[kiloRAM]

That's impressive and really nice looking. I was surprised with my 8 MPG while towing. 5.5 is shocking. It is a beautiful setup you got though.

 

[tjfdesmo]

Hi guys, the Wife and I got the camper and pulled it back to PA from Michigan. Added a Magnaflow exhaust, a CAI and Airlift stabilizer bags to the beast since I bought it. Truck pulled the load like a champ but the highway was mostly flat. So far, so good. If I have any complaints it would be the fuel mileage was shocking at 5.5, was hoping for a little better but with only 4k on the odometer maybe it will get a little better or just wishful thinking. lol Going to put her to the test this summer in the rockies with camper in tow, can't wait to see the mileage going up those mountains!!View attachment 161462

Have you put your setup on a scale? I am pulling a 41' gooseneck toyhauler, GCW 23,160, and generally get 7-8, with lowest so far 6.5 mpg.My toyhauler is built like a LQ horse trailer so it is lower profile than what you are pulling. Looking into going back to a Cummins now, and a dually this time.

 

[Slick rick 2500]

Hi guys, the Wife and I got the camper and pulled it back to PA from Michigan. Added a Magnaflow exhaust, a CAI and Airlift stabilizer bags to the beast since I bought it. Truck pulled the load like a champ but the highway was mostly flat. So far, so good. If I have any complaints it would be the fuel mileage was shocking at 5.5, was hoping for a little better but with only 4k on the odometer maybe it will get a little better or just wishful thinking. lol Going to put her to the test this summer in the rockies with camper in tow, can't wait to see the mileage going up those mountains!!View attachment 161462

Nice to see another big rig pulled with a 6.4. I love my 2015 6.4 2500 4x4. I pull a heartland e326 10xxx bare 115xx loaded. I pull all over the west. Living in vegas travelled to Bellingham Washington a few times. Hunnington beach alot. Lake Navajo in a few weeks. I just deal with the 5.9 mpg. Have a aux fuel tank helps a little. I can now make it to Huntington beach on with no re fueling.

 

[Moto006]

Have you put your setup on a scale? I am pulling a 41' gooseneck toyhauler, GCW 23,160, and generally get 7-8, with lowest so far 6.5 mpg.My toyhauler is built like a LQ horse trailer so it is lower profile than what you are pulling. Looking into going back to a Cummins now, and a dually this time.

Haven't put the rig on a scale yet but plan to in the future. Camper is 12500 dry so a little quick math I can get a ballpark figure. If I can get 7-8 mpg in the future I'd be happy! Haha. Thanks for the compliments guys and I'll keep updating the fuel mpg in the future. Hey Slick Rick 2500, do you have the info on a aux tank for a gasser? The only thing I found so far is for diesel.

 

[olyelr]

Nice to see another big rig pulled with a 6.4. I love my 2015 6.4 2500 4x4. I pull a heartland e326 10xxx bare 115xx loaded. I pull all over the west. Living in vegas travelled to Bellingham Washington a few times. Hunnington beach alot. Lake Navajo in a few weeks. I just deal with the 5.9 mpg. Have a aux fuel tank helps a little. I can now make it to Huntington beach on with no re fueling.

Auxiliary fuel tank?

 

[pcschwenke]

We have a 3500 with 6.4l & 4:10 gears pulling a 9300lb trailer and 1500lbs of extra payload. We typically get 9-10mpg running 89-93 octane gas.

 

[Moto006]

Auxiliary fuel tank?

Yes, auxiliary fuel tank. The only thing I found so far is for a diesel and if the mpg does not improve, I would like to not have to stop to refuel every 2 hours.

 

[tjfdesmo]

Yes, auxiliary fuel tank. The only thing I found so far is for a diesel and if the mpg does not improve, I would like to not have to stop to refuel every 2 hours.

Even with a Cummins the fuel tank size is a joke. But with the 6.4 it's a crime. Out west it can be a long long ways between fuel stops, so I am continuously planning fuel stops. The MyPilot app is pretty handy to find Flying Js with RV pumps. Ram needs to at least offer a bigger tank as an option. At least with the Cummins you can go to Titan or Transfer Flow and replace the peanut tank with a 55 gallon and not take up bed space with an aux tank.

 

[NewBlackDak]

Even with a Cummins the fuel tank size is a joke. But with the 6.4 it's a crime. Out west it can be a long long ways between fuel stops, so I am continuously planning fuel stops. The MyPilot app is pretty handy to find Flying Js with RV pumps. Ram needs to at least offer a bigger tank as an option. At least with the Cummins you can go to Titan or Transfer Flow and replace the peanut tank with a 55 gallon and not take up bed space with an aux tank.

I really don’t understand what is going on with the Titan tanks. The fuel tank on gas and diesel is the same part number, so the Titan tank should just work. Nobody has been gutsy enough to try it.


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[tjfdesmo]

I really don’t understand what is going on with the Titan tanks. The fuel tank on gas and diesel is the same part number, so the Titan tank should just work. Nobody has been gutsy enough to try it.


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Agree 100%. I think it has to be a longbox, though, right???

 

[sandawilliams]

Even with a Cummins the fuel tank size is a joke. But with the 6.4 it's a crime. Out west it can be a long long ways between fuel stops, so I am continuously planning fuel stops. The MyPilot app is pretty handy to find Flying Js with RV pumps. Ram needs to at least offer a bigger tank as an option. At least with the Cummins you can go to Titan or Transfer Flow and replace the peanut tank with a 55 gallon and not take up bed space with an aux tank.

I live in the west and know what your talking about. Try going through Canada and Alaska. The 7 gallons of extra gas I carried saved me a number of times. I have found larger aftermarket tanks that will work in our trucks but the spare tire has to be re-located. I don't have room for it anywhere but where it is.

 

[olyelr]

Yes, auxiliary fuel tank. The only thing I found so far is for a diesel and if the mpg does not improve, I would like to not have to stop to refuel every 2 hours.

Exactly. Thats why i am questioning what he is using.

 

[JFR Johnny]

I use Mobil 1 0w40.. hope its ok.