Here is how this works. A higher stall speed torque converter allows the Rpm’s to increase when you launch from a start. The Stall speed is rated at a ‘flash’ speed. To get that flash speed for your car, just punch it from idle and watch the tachometer go up before the car starts to move. The reading you get will be the flash stall speed that your stock torque converter has now.

A higher stall speed torque converter allows more ‘slip’ so the Rpm’s increase before the torque converter locks up. If you make modifications to your car that include a longer duration camshaft (230 degrees @ .050 lift), you want a higher stall speed torque converter because your motor has lost bottom end torque and will be lazy off the line. That is, your motor does not have the low speed torque it had with the shorter duration camshaft (218 degrees @ .050 lift).

You can upgrade to a higher stall speed torque converter without changing your camshaft. This would increase your launch by letting the Rpm’s slip until say 2200Rpm’s.

Remember that a torque converter doubles the engine torque to the wheels. That’s why an automatic transmission vehicle will jump off the line faster than a manual transmission vehicle if they both launch at the same Rpm. Also, higher stall speed torque converters develop more HEAT due to the increased slippage and will require additional cooling requirements.