What exactly does the "stall" rating on a torque converter mean? I guess it is usually measure in rpm. When a person upgrades their engine and changes the stall on the converter, what result are they getting from this? I am gradually learning about the automatics but need a little help. Thanks alot!
well the easiest way I can think to explain it is the amount that the engine can rev before the tranny will fully ingauge. if you install a large cam you need for the converter to "slip" so when you put it in gear it will noy lung forward and kill the engine. also it alows the engine to reach its rpm rang to where its making power before it starts "loading" the transmission. usually a cam shaft will say what converter it needs to operate and you always want to mate all of the after market parts you use ie.....cam, intake, carb,headers,ect........also when running a stall you will need to run some lower gears high gears and a stall do not work together.
Convertor stall in any given car is a function of torque the engine is able to make, the weight of the car and the gearing. In a Mav with the C4 trans and a stock 302 v8, the normal hook up for 'drive away' is about 1200 rpm. The flash stall would be several hundred rpm higher. The differences in brake stall and flash stall is in how the convertor reacts to applied torque. Flash stall is when a sudden application of full throttle is done and results in a sleigtly higher stall rpm. Brake stall is the application of the brakes to keep the car from moving and a full throttle application of power to the point the convertor will limit the engine RPM. The stall in relation to perfromance is a matter of matching the stall speed to the beginning of the 'fast rise' in engine torque, toward it's peak. The two togather makes better use of the power the engine produces without waisting the time interval below this torque point until the engine starts to pull hard. When the engine is modified for more torque, and /or the RPM at which the torque starts to rise fast, is raised, the convertor stall selection should rise with it to make the best use of the power. When lowering the rear gear ratio, this will also raise the stall point (of the convertor) due to the extra torque multiplaction loading on the convertor that the engine is trying to overcome to move the car. Sorry for the long speel but it is not easy to convey without a lot of explanation to cover the main points and there is more to it yet.
Thank you guys. It makes sense to me. I may still have some other questions when I go to buy one but I will asked them as I come up with them.
easier explained this way. Place two fans face to face, as close to each other as you can. Turn one of them on, the airflow from it causes the other to spin the opposite direction. This is how a torque converter works. Place them further apart, and the fan that's being powered (the one that's turned on) will have to turn faster to spin the other one the same speed. This is basically what they do to increase stall speed--alter the angle of the blades inside the converter and/or make it a smaller diameter to reduce fluid velocity. Higher stall speed converters basically cause "slippage" inside the converter, thus creating lots of heat. That's why converter companies recommend adding a cooler when changing converters.
