Engine RPM and fuel economy

[rjanuszewski]

Just got a 2025 Lonestar with the SO hurricane engine. I noticed that the RPMs exceeded 2000 when going over 70 and there was a dip in fuel economy to around 15 and 16 MPG. I recently had a loaner with the same engine and transmission but noticed lower RPMs and obviously better fuel economy while driving the same. Not sure of where the RPMs should be when driving at 75 MPG where I have higher speed limits.

 

[FloridaSun]

Noticed same thing in my HO..sits at 2000...my 2020 would hit OD and drop to 1400 to 1500.....on the flip side hit the pedal and you better have something to hold onto...

 

[Scram1500]

Just got a 2025 Lonestar with the SO hurricane engine. I noticed that the RPMs exceeded 2000 when going over 70 and there was a dip in fuel economy to around 15 and 16 MPG. I recently had a loaner with the same engine and transmission but noticed lower RPMs and obviously better fuel economy while driving the same. Not sure of where the RPMs should be when driving at 75 MPG where I have higher speed limits.

My guess is your truck has a 3.92 and the loaner had a 3.21 gear ratio

 

[Skater]

My guess is your truck has a 3.92 and the loaner had a 3.21 gear ratio

I would agree with Scram1500. Does your truck feel like it has more pep of the start and is quicker to get up to speed than the loaner? If so, the gearing is likely what Scram1500 said.

 

[rjanuszewski]

It is the 3.92 in my truck. Had to look at the windows sticker.

 

[LITTLEREBEL]

It is the 3.92 in my truck. Had to look at the windows sticker.

From my knowledge, the 3.92 is a better all around gear.

 

[rjanuszewski]

Thanks

 

[Zeeya]

The rebel comes with 392 gears and as you mentioned at 70 mph I ran about 2000 rpms, where as the Laramie my bud has is the 321 gears. Like mentioned above it was down around 1550.

 

[jmr]

The S/O has 3.55 gears standard and 3.92 optional all H/O have 3.92. The 5th gen Ram with 5.7L had 3.21 gears standard and 3.92 optional the 3.6L had 3.55.