30,000 lbs behind the Ram
Clicky The Rams time was almost exactly what I expected out of a 385 hp engine. Using the same formula the 440 HP Powerstroke should have made the run in 10.5 minutes.
Forum Discussion
Cummins12V98 wrote:
Downshifting with the Aisin trans is a waste of time when climbing a grade. I have tried it thinking a higher RPM would net a higher MPH. Downshifting while descending does work well by keeping the RPM in the high 2,000's.
Combined 33K in 2nd would hold around 33 MPH as seen in video on this 14 percent grade.
Wow. Impressive.
I haven't seen a torque curve for the new 900 lbft Cummins but you can be certain that at 1900 rpm the engine is making no more than 325 hp. If you downshift at 2100 from 4th to third you will jump to 2800 rpm where your making 385 hp. I'm not sure what the torque value of the cummins is at 2100 rpm but I do know that by downshifting from 4th to third at 2121 rpm brings your engine rpm up to 2800. At 2800rpm the engine makes 722 lb ft of torque. When that torwue is multiplied by the 1.32 third gear ratio your definitely going to gain making the downshift. You're equivalent to 953 lbft of torque in 4th gear which is more torque than the engine can deliver at 1800 rpm and you don't have to slow down to get it. I wouldn't necessarily make the shift but if I knew the hill was going to cause it to happen anyway I would shift sooner rather than wait.
