3.25 vs 3.55

11R22.5

 

I have 3.58's. ISX /450. 70MPH for me is about 1625 rpm.

22.5 LP

 

You’d be running about 75 in the big hole at 1400, assuming a .74 OD transmission.

 

I would ideally cruise around 1150-1200RPM since the Cummins peak torque curve is 1150RPM. and I am considering getting the 505HP 2050 TQ version instead of 525HP. I would be pulling reefer and staying consistently loaded for the most part. So I want enough power to get me up steep grades with 75,000 LBS but also want somewhat decent fuel economy

 

The other thing would be similar weights but stepdeck

 

http://www.roadranger.com/ecm/groups/public/@pub/@eaton/@roadranger/documents/content/ct_062746.swf

3.25 = 71.1 mph @ 1400 rpm
3.55 = 65.1 mph @ 1400 rpm

If you aren't pulling over 80,000 lbs and aren't pulling a lot of big hills, your 3.25's will be fine.

 

I had this almost exact setup with that motor. You will like it i think.
Only difference was my tires were 22.5LP....
If you go with 11R you might want a 3.25 or 3.36 rear ...

These motors aren't the same as the older ones that needed lots more RPM...

honestly doing it again, I'd go 500/1850 Efficiency , that 2050tq isn't a crazy power difference for the extra fuel consumption...

Plus that E series pulls further down to 1,000rpm which might actually be more useful real world business sense too, saving more fuel.

 

I have a 2017 Kenworth t680 with the Paccar MX 13 and 3.15 radiu and 22.5 Hankook tires, does anyone know the sweet spot for this truck?

 

very interesting that 1650 is where the fuel mileage is. On 13 speed 3.25s? When do you use the high gear then? When you gotta make time and speed up only?