Quote:
Originally Posted by rtspence
Based on information from Camp Freightliner the ISL9 sweet spot is 1800- 1900 rpm for power & economy. Your speed will be determined by gear ratio an tire diameter.
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I have the 300HP Cummins ISB. At 65 MPH, the Allison transmission downshifts for smaller grades. At 67-70, the Allison will hang in there longer on the grades. 67 MPH is right at 1,800 RPM. I try for 67-70 MPH if the traffic permits the use of cruise control.