If a converter will stall 3000 rpm with 200 ft lbs of torque, then doubling the stall to 6000 rpm will take four times the torque, or 800 ft lbs. If you find the square root of 200ft lbs, then divide it into the rpm the converter stalled at, (3000) you get what they call the K factor. Do the same with 800 ft lbs, divide the 6000 rpm by that square root of 800 and you will get the same number, or the same K factor. So the K factor is the constant that will tell you what stall speed you will have once you know how much torque changed. Multiply the square root of the torque by the K factor and you get the stall speed.