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
4x4ord wrote:
^^^ I figure a Ram towing a typical 20,000 lb toy hauler should get around 9 mpg at 62 mph. If you use the BSFC map that we have and figure the Cummins will be running in the 205 g/kwhr area of the bsfc map we can come up with the kw required to tow a 20k trailer at 62 mph. 9 miles per gallon is 22182 grams of fuel per hour. 22182/205 = 108 kw or 145 HP. From there you should be able to come up with what you think are reasonable numbers for surface area, rolling resistance and coefficient of drag.
(Keep in mind that the calculated power requirement is at the crankshaft so rear wheel hp would only be about 123 to 125 hp.)
I'm trying the Powerstroke with 10 spd first, as it's a real combo and we can calibrate against real life performance.
First the curve fitting based on your numbers, a 5th order poly provides near exact fit, with R^2 of 0.9998:
I re-calculated hp using the equation in the last column, and numbers are near perfect to the input.
For the model, I used a mass of 43,500 lbs, full GVW of an F450. Cross section area of 75 sq ft, based on J2807's max for travel trailers. I guessed a Cd of 0.80. Tire diameter based on 245/75R17, and tire coefficient of 0.015. I'm starting out full throttle on 7% grade, as a "torture test".
The model uses a column for each gear, each row is 0.1s time step. Based on initial launch rpm (2000), it uses the hp curve to calculate final net thrust: gross thrust minus air drag, tire drag, and gravity. Net thrust calculates instant acceleration, which gets ups the new starting speed for the next 0.1s time step:
