From my friends over at
Edge Racing Converters
What is Stall?
The easy answer is: The RPM a torque converter will allow the engine to attain with a given engine torque input.
How is Stall measured?
That's where the confusion begins between the racer and the builder. Stall is measured in three different ways. TRUE, BRAKE and FLASH Stall. The only true way to set stall is using TRUE stall math.
What is TRUE Stall?
True stall is measured with the transmission locked (Trans brake) and the drive shaft still. The throttle is then fully depressed and held to obtain the holding RPM of the torque converter. This is the "TRUE" Stall.
TRUE Stall is the only real way to insure that the stall converter is set up properly for the intended combo.
What is foot Brake stall?
This is attained with the transmission in gear and the brakes depressed fully. Now slowly apply the accelerator. The RPM the engine reaches the moment before the tires spin is known as the "BRAKE" Stall
BRAKE Stall in not a consistent way to measure your stall converter and has many variables. This method will be lower then TRUE stall by 600-1000 RPM
What is FLASH Stall?
Flash stall is generally read while the car is in motion. While rolling at a slow speed the throttle is depressed fully to see where the RPM will flash (or peak)
This method will not be true if tires spin or car is rolling too fast.
Due to the turbine already turning in converter we end up with less torque multiplication.
This will give you a lower stall reading of between 200 and 800 RPM under the converters TRUE stall in the same application.