A typical 12-inch stock converter (shown right) loses about 250 rpm at cruise speed, and a high-stall 10-inch converter (shown left) loses much more rpm. If you won't be running a transmission that uses a lockup converter, you may want to choose a converter with less stall speed to maintain fuel economy. Just remember to match the engine's camshaft to the converter. Typically, torque converters with less stall speed should be paired with engine camshafts with shorter amounts of duration. Check with the cam company for a recommendation.