AmericanMuscle4.6GT

its all about your torque curve. study it, and see where power drops off significantly, shift before that, but high enough that you'll still be in your powerband when the next gear hits. its different in every gear, obviously an example is 3rd to 4th

GT Bob

Not exactly true. You have to take in to account the torque multiplication going on in the transmission as well. To make it easier to understand, let me give you an example and understand that these numbers are just for ease of illustration.

Now, that is a SUPER simplified explanation, but it gets ya started in the right direction. Now, you have to add in the inertia of the car, the powerband the car has, Gear ratios in the trans and rear, and about 3 million other variables and you begin to see where this gets complex. Auto crossers may hold a gear and push the RPM's simply for the benefit of maintaining power thru a turn, whereas drag racers wanna burn thru the gear and get to the next one. It depends on application.

A good rule of thumb for Drag racing is, you want to come out of gear just after peak power, and come back into it right before peak torque. Ideally, mechanically, this will always happen. However realistically, it rarely does so my rule of thumb is, shifting into 2nd, you time the shift to come in just before peak torque, and run it out to just past peak power, and come into third wherever that puts ya.