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Showme_5vr's avatar
Showme_5vr
Explorer
Feb 24, 2023

RAM 3500 with HO 6.7L Cummins SRW

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
  • 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.
    Thanks



    Pretty 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.
  • 4x4ord's avatar
    4x4ord
    Explorer III
    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.
    Thanks



    Pretty 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.
  • 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.
    Thanks



    Pretty 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 .