Driving With Torque and a dead lift pump.

[Rich-n-Linda]

Originally Posted by capnqball

My ISB 340 HP/660 # torque comes out to 2705 !!! Cummins tells me that its safe to run 2600/2800 "all day long" but the specced torque peak is at 1550 rpm which isn't even close to that 2705. So that formula above doesn't seem to work for my B series.

That formula is right. When climbing a grade you do not want to be at the torque peak RPM! You want to run at or near the HORSEPOWER PEAK RPM, and that would be at a much higher RPM.

As I stated earlier in this thread, attempting to climb a grade at the torque peak RPM is a sure-fire recipe for lousy grade climbing performance and overheating. I don't know where this nonsense about climbing grades at the torque peak RPM got started, but it is wrong information that will definitely cause problems.


Rich & Linda
'06 Mandalay 40E
Freightliner XC-R chassis
Cummins 400 HP ISL

[hes4all]

KNow your coach is the key here.

I like to drive at 1650-1700 rmps with the economy button on. For most slight grades I leave the cruise on. But when a steeper climb comes I will down shift to keep my rpm's at 1950 or higher.

This is what works for "me". Your results maybe vary?

My coach like this style of driving, mileage stays better, temps stay down and I move right along!

My last trip was last month to Silverton Colorado. If you haven't been thier then I will tell you that it is a steep long climb. With this driving style my highest temps were: Trans 205, engine 204.

I weighed in at 44,000 gross!