X2, the usual model for stall speed is the most frequent buyer: SBC 350. In round numbers, torque near stall speed is proportionate to displacement X static CR. The industry has created a rating factor for comparing torque converters, the “K” factor: RPM = K × (T^.5). Some manufacturers supply this data; if attempting to approximate it remember that the relevant torque output is not necessarily peak torque (although with a very high stall speed it will be close), but the torque at the (probably lower) actual stall speed. If the manufacturer identifies your converter stall speed as 3,200 RPM, this was almost certainly with regard to its characteristics with a Chevrolet V8 engine developing perhaps 350 ft./lbs. of torque at that speed (which places the K factor value at 170). When installed behind your L6 engine developing perhaps 230 ft./lbs. of torque at that speed, the actual stall speed will be closer to 2,600 RPM.
