Just discovered that the new RAM we ordered has been built and is waiting to ship. The 2015 RAM 2500 with the regular 6.7L Cummins that we have now will get around 20-21 miles per gallon when running empty on a trip. Does anyone have experience with the HO on fuel mileage? Both trucks have the 3.73 rear end.Thanks

Showme 5vr wrote:Just discovered that the new RAM we ordered has been built and is waiting to ship. The 2015 RAM 2500 with the regular 6.7L Cummins that we have now will get around 20-21 miles per gallon when running empty on a trip. Does anyone have experience with the HO on fuel mileage? Both trucks have the 3.73 rear end.ThanksPretty sure your 2015 SRW has the 3.42 rear end ,unless you put 3.73's in it . As far as mileage no idea , but would stand to reason having 3.73 in the new one ,probably slightly less mileage would be my guess .

cummins2014 wrote:Showme 5vr wrote:Just discovered that the new RAM we ordered has been built and is waiting to ship. The 2015 RAM 2500 with the regular 6.7L Cummins that we have now will get around 20-21 miles per gallon when running empty on a trip. Does anyone have experience with the HO on fuel mileage? Both trucks have the 3.73 rear end.ThanksPretty sure your 2015 SRW has the 3.42 rear end ,unless you put 3.73's in it . As far as mileage no idea , but would stand to reason having 3.73 in the new one ,probably slightly less mileage would be my guess .The High Output also has a lower compression ratio which is also likely to contribute to poorer fuel economy when empty. On the other hand, I would guess that neither the gear ratio nor the lower compression ratio will have much affect on the truck's towing mileage.

4x4ord wrote:cummins2014 wrote:Showme 5vr wrote:Just discovered that the new RAM we ordered has been built and is waiting to ship. The 2015 RAM 2500 with the regular 6.7L Cummins that we have now will get around 20-21 miles per gallon when running empty on a trip. Does anyone have experience with the HO on fuel mileage? Both trucks have the 3.73 rear end.ThanksPretty sure your 2015 SRW has the 3.42 rear end ,unless you put 3.73's in it . As far as mileage no idea , but would stand to reason having 3.73 in the new one ,probably slightly less mileage would be my guess .The High Output also has a lower compression ratio which is also likely to contribute to poorer fuel economy when empty. On the other hand, I would guess that neither the gear ratio nor the lower compression ratio will have much affect on the truck's towing mileage.That is less than a 10% gear ratio change so it shouldn't have a big effect. You don't generally see a large drop on diesel fuel economy until you start getting out of their torque range. The drop in torque is largely due to less efficient combustion.

2oldman wrote:quote festivalIndeed. :)

RAM 3500 with HO 6.7L Cummins SRW | Good Sam Community

Cummins12V98
Explorer III
Mar 02, 2023
Larry stays quite busy, he is a Wood Magician.
Grit_dog
Navigator
Feb 28, 2023
larry barnhart wrote:
for our combined 22,900 lbs. I didn't have any issue with a 5 sp Allison Duramax awesome truck. Not saying it would be great for a much bigger fifth but I was happy. No issues going down mountians. Now I get to look at it everyday waiting for me to get some fresh air. chevman

:(
I feel for ya Larry. I know what you’re going thru. Stay strong!
larry_barnhart
Explorer
Feb 28, 2023
for our combined 22,900 lbs. I didn't have any issue with a 5 sp Allison Duramax awesome truck. Not saying it would be great for a much bigger fifth but I was happy. No issues going down mountians. Now I get to look at it everyday waiting for me to get some fresh air. chevman
Cummins12V98
Explorer III
Feb 28, 2023
Grit dog wrote:
Me Again wrote:
My F-150 has a 10 speed and it spends a lot of time shifting gears, sometimes skipping a gear. I am sure that 7 or 8 would have been just fine behind the 2.7L ecoboost that has a broad torque curve down low. It is said that it is snappier and more fun to drive than the 3.5L ecoboost.

I agree. 8 or 9 forward gears is the practical max/ideal gears needed. The 10 speed like you have only has about 150 rpm’s diff between 9 and 10. That’s one gear split not needed.

I don't need "SPLITS". :B
Grit_dog
Navigator
Feb 26, 2023
Me Again wrote:
My F-150 has a 10 speed and it spends a lot of time shifting gears, sometimes skipping a gear. I am sure that 7 or 8 would have been just fine behind the 2.7L ecoboost that has a broad torque curve down low. It is said that it is snappier and more fun to drive than the 3.5L ecoboost.

I agree. 8 or 9 forward gears is the practical max/ideal gears needed. The 10 speed like you have only has about 150 rpm’s diff between 9 and 10. That’s one gear split not needed.
Me_Again
Explorer III
Feb 26, 2023
My F-150 has a 10 speed and it spends a lot of time shifting gears, sometimes skipping a gear. I am sure that 7 or 8 would have been just fine behind the 2.7L ecoboost that has a broad torque curve down low. It is said that it is snappier and more fun to drive than the 3.5L ecoboost.
Grit_dog
Navigator
Feb 26, 2023
Cummins12V98 wrote:
Grit dog wrote:
And yes, a new 3.73 HO will not get as good of empty cruising fuel mileage as a 3.42 standard Cummins.
But if they’re both srw trucks, the difference should not be huge. Maybe a couple mpgs.

Also, I’d wait for a 2024 model…..can’t say why, but anyone halfway well read about Ram’s current and future transmission options will understand.
I’ll throw out a clue. 12V says this will not be a worthwhile change….lol.

This transmission change has been "going to happen" for several years. We will see what if anything changes in 2024. So far RAM has not caved to the "more is better" mentality.

Icbw, but will have to wait and see. That’s all I’ll say aboot that.
But “Ram has not caved to the more gears is better, is laughable, and nothing more than your own personal theory and undying love for the Aisin trans.
They were late to the table with Hd gassers with >6 speeds as well. And the 66rfe that was replaced by the 8HP was far too long in coming.
However, who lead the US (and Jap truck) market in introducing the 8HP pretty much, no, completely, across their rwd/4wd platforms from cars to suvs to light duty pickups in 2015?

Yup it was Chrysler. Not Ford, GM, Yoda or Nissan.
Ram didn’t “cave in” even though they were real world testing the ZF Powerline back in like 2018? Iirc.
Your theory is simply that of unfounded opinion vs what really happened at FCA/Stellantis over the last 5 years or so. Ram has been long overdue for an upgrade in this department.

Maybe I’ll eat my words but I bet you’ll see your beloved AS69rc and the old maligned 68rfe bite the dust for good here real soon! Hopefully….
Cummins12V98
Explorer III
Feb 26, 2023
Me Again said: "I still think they got rid of the 3.42's as a concession to the 68 RFE's taller 1st and 2nd gears."

100% agree! Take those gears and put them behind the AISIN with it's lower starting gears and you have a GREAT combo for towing and running Bobtail.

To order my truck again I would skip the 4.10's and order the 3,42's. I would tow at 60 at 1,750 rpm's in 5th the same turns as 4.10's in 6th. YES even at my 35k combined and West Coast Towing!!!
Cummins12V98
Explorer III
Feb 26, 2023
Grit dog wrote:
And yes, a new 3.73 HO will not get as good of empty cruising fuel mileage as a 3.42 standard Cummins.
But if they’re both srw trucks, the difference should not be huge. Maybe a couple mpgs.

Also, I’d wait for a 2024 model…..can’t say why, but anyone halfway well read about Ram’s current and future transmission options will understand.
I’ll throw out a clue. 12V says this will not be a worthwhile change….lol.

This transmission change has been "going to happen" for several years. We will see what if anything changes in 2024. So far RAM has not caved to the "more is better" mentality.
Me_Again
Explorer III
Feb 26, 2023
If I kept my 2015 3500 4x4 HO SBW SB Laramie at 70 MPH it would break the 20 mpg barrier easily. Towing at 24,500 lbs combined with tall 5th wheel netted 10.5-11 mpg. Did I ever say, "I loved my 3.42 gears"? 80 MPH at 1750 rpms.

I still think they got rid of the 3.42's as a concession to the 68 RFE's taller 1st and 2nd gears.