Hello Snowtoy,
Here's my real world. I will be running 31" tires, R&P 4.10s. My RPM in 5th gear is calculated to be approximately 2900 at 80 MPH, right were I want it, which is the beginning of my projected peak torque range for my engine rebuild.
Changing R&Ps to 4.56 will move my RPM in 5th gear to 3200 RPM, which is in middle of peak torque, NOT where I want.
I want the RPM in 5th gear at 80 MPH to be at or near 2900 because if I drop down to 4th gear, at say 70 MPH my RPM will be approximately 3200 right in the middle of my peak torque range - right where I want it.
Now I have two gears that I can use to take advantage of my peak torque and pull steep grades or buck head winds while traveling at freeway speeds.
With 4.10s if I need to drop down to 3rd gear, my RPM at 50 MPH will be about 3200 RPM, right in the middle of my peak torque range - right where I want it to be.
It does not matter whether my torque and HP numbers are calculated at brake or at the rear wheels. Whatever power is produced to my rear tires, and whatever energy is absorbed, I will have my peak torque range right where I want it at the rear tires.
Gnarls.
