What is stall speed?

Question

I am having trouble understading the significance of stall speed on an automatic transmission

Please explain what it means.

Also, how do different stall speeds impact acceleration?

Answer 1

Stall speed refers to the torque converters theoretical fluid lock up point, basically the point at which the engine doesn't have any more torque available to shear the fluid.
Installing a converter with a higher stall speed allows the engine to get farther up in its power band, so when you leave the line the engine will be doing a higher RPM and creating more horsepower.
Traditionally high stall converters were needed for high RPM engines because at the normal 1200 RPM or so these engines didn't have anything on the bottom of the tachometer.
Let alone if you've got one that wants to idle at 2000 RPM and the converter will not let it get past 1000. ( so the bastard is tugging at the line with the brakes pinned to the floor )
In an average hot rod a high stall converter and lower rear gears can shave a good 1.5 to 2 seconds off the quarter mile.
Modern high fuel millage cars are built with popcorn fart tight lock-up converters so that no energy is wasted.
The old school common one was to put a Vega converter on a Chevrolet V8. OH YEA.

Answer 2

The stalling speed is the airspeed at which the airflow over and under the wings can no longer support the aircraft and it will just fall. Basically the faster a plane goes the more lift is produced by the wings. The slower, the less lift is produced. Flaps are extendable surfaces on the wing that increase the wing area. The more wing area the more lift is produced for a given airspeed. When you are travelling in a car, put your hand out of the window and level with the ground. Then tip your hand so the front edge is higher. See how the airflow lifts your hand more? Its the same principle. To get an aircraft to cruise at the required speeds safely you dont want that extra lift so you have to retract the flaps so you have a clean wing (a normal shaped wing). On approach and landing and take off it involves low speed handling and the flaps enable the pilot to increase their level of control and lower the landing speeds so it is safer for the aircraft or passengers. The stalling speed is a certain speed (different for all aircraft and changes in weather conditions) at which the flaps do not compensate for the lack of airspeed and the plane will just fall, literally. The nose of the aircraft may still be level with the horizon or even pitched up but its still losing height and falling. To prove it do the hand thing on a main road then slow down and see how it affects the lift on your hand. No matter what angle you put your hand at it will fall, thats stalling because there is insufficent lift.

Answer 3

It's the speed in revolutions per minute when the torque converter in your automatic transmission stops slipping. A stall speed that is too low will cause your engine to lug, and maybe stall if it is really low. Ideally you want a stall speed that matches the torque and power curve of your engine so that the transmission stops slipping as you approach maximum horsepower and torque condidions. At that point max horsepower and torque is transferred directly to your driving wheels giving max acceleration.

Answer 4

you know on a manual car when you put it in gear and lift the clutch the engine will stall if there arent enough revs. well an automatic gearbox has to have a rev speed set right, too little revs and the engine will stall when you go to move away

Answer 5

aim your vehicle in a safe direction---step on the brake---push the throttle to the floor---quickly read stall speed on tachometer and release throttle

horse power increases as engine speed increases [ within limits] and initial acceleration will be greater