[AdamIsAdam]

Originally Posted by pastry_chef

Where is 704 and 705 coming from?
What are the gear ratios?

What hits the rear wheels is the important thing.
If you provide your specifics I can show you both methods that end up with the same final result.

Using the formula from EE's video and my own torque curve from when I first dyno'd the car on the chassis dyno 3 years ago, I got the following math:

2.2 (1st gear) x 320 lb.ft = 704lb.ft @ 5300 RPM
1.64 (2nd gear) x 430 lb.ft = 705 lb.ft @ 3950 RPM

and to get the RPM drop of 3950 it was:

2.2 5300
---- * ------ = 3950
1.64 x


At a 5300 shift point, the torque was the same before and after the shift.