what does a stall converter do

A stall converter is a type of torque converter that has three stages of operation: stall, acceleration, and coupling. Stall is when the transmission is in gear, but the brakes prevent the car from moving. At stall, the torque converter can produce maximum torque multiplication, called stall ratio, if sufficient input power is applied. A stall converter is designed to hold back the engine speed when the transmission output is prohibited, and the stall speed is the speed at which the converter holds back or limits the engine speed. The stall speed is important because it determines the engines RPM stalls and the gap between where the vehicle idles and begins to move. A high-performance torque converter, like the ones sold at RevMax Performance Torque Converters, can increase launch and get the car off the line quicker if the proper stall speed is selected. The proper converter stall depends on many things such as cam selection, vehicle weight, engine torque, and other factors. The internal parts and characteristics of a converter must be matched to the intended vehicles specs. Higher stall ratio converters tend to provide more possible torque multiplication, but they are usually relatively inefficient below the coupling speed, whereas low-stall ratio converters tend to provide less possible torque multiplication. It should be noted that higher stall converters slip more and build up lots of heat, which requires aftermarket coolers to keep transmission oil temperatures down.