2021 Cummins 1075 lbft peak torque at 1356 rpm
Apparently the 2021 Cummins makes its peak torque of 1075 lbft at 1356 rpm. Are you still impressed?
Forum Discussion
I don't think it worth doing the math to see how much faster you'd be able to pull the hills but your chart demonstrates a clear advantage on the steeper hills where you could gain as much as 15 HP over the 6 speed. And as you've pointed out on very tough pulls the drop to 2nd might be a bit of a hole. I think the Cummins can put out good power to at least 3000 rpm though and 3000 rpm in 2nd is 41 mph. A hill that would bring the Cummins to its knees in 3rd gear (down to 40 mph) pulling an 18000 lb trailer would be about a 10% grade.
I also see according to your chart I should have dropped the torque off slightly faster after after 2800 rpm ... (peak HP is supposed to be 420 @ 2800 and your chart is showing 423 HP at 2892rpm.... oops)
(Edit: I checked the data I put in to draw the chart and @ 2900 rpm I have the torque at 752 lbft so 415 HP. I have the curve dropping off a little sharper after 2600 rpm so that peak power of 420 is obtained at 2800 rpm.)
For fuel economy purposes pulling hard at 60 mph is probably a good scenario to run (201 HP or 150 Kw) .... This might be towing into a stiff enough wind to bring the fuel economy down to 6.7 mpg.
I'd be 5th gear 1674 rpm and 856 Nm ... so 192 g/kwhr and 6.7 mpg
You'd be 8th gear/1848 rpm and 775 Nm .... and the same 192 g/kw hr and 6.7 mpg
Then it is probably good to see what happens with a lighter trailer ... say one where we are able to get about 11 mpg at 65 mph.
This would be when 93 KW could carry us along at 65 mph.
We'd be in high gear at very similar rpms
I'd be 1484 @ 598 Nm
You'd be 1489 @ 596 Nm
We'd both be 205 g/kwhr or 11 mpg
I also see according to your chart I should have dropped the torque off slightly faster after after 2800 rpm ... (peak HP is supposed to be 420 @ 2800 and your chart is showing 423 HP at 2892rpm.... oops)
(Edit: I checked the data I put in to draw the chart and @ 2900 rpm I have the torque at 752 lbft so 415 HP. I have the curve dropping off a little sharper after 2600 rpm so that peak power of 420 is obtained at 2800 rpm.)
For fuel economy purposes pulling hard at 60 mph is probably a good scenario to run (201 HP or 150 Kw) .... This might be towing into a stiff enough wind to bring the fuel economy down to 6.7 mpg.
I'd be 5th gear 1674 rpm and 856 Nm ... so 192 g/kwhr and 6.7 mpg
You'd be 8th gear/1848 rpm and 775 Nm .... and the same 192 g/kw hr and 6.7 mpg
Then it is probably good to see what happens with a lighter trailer ... say one where we are able to get about 11 mpg at 65 mph.
This would be when 93 KW could carry us along at 65 mph.
We'd be in high gear at very similar rpms
I'd be 1484 @ 598 Nm
You'd be 1489 @ 596 Nm
We'd both be 205 g/kwhr or 11 mpg
