[reeds98gt]

i have a 98 gt with a auto transmission i have heard people talk about changing out the torque converter with a different stall speed. can someone explain what that does? my car is stock but here are the mod i have in the works. 373 gears, pi intake, tb and plenum, long tube headers,h pipe no cat, cat back system.
thanks for the info.

[White99stang]

well from what i know about it when you put the stall in there you can foot brake it up to that stall speed, so if you got a 4000rpm stall i think you can push the brake and rev up to 4000rpm and launch that way.

[Drgnracin72]

exactly. makes you launch b etter so you dont launch from idle. akes for better times

[1slo5.0]

Originally Posted by White99stang well from what i know about it when you put the stall in there you can foot brake it up to that stall speed, so if you got a 4000rpm stall i think you can push the brake and rev up to 4000rpm and launch that way.

Close. The only way to get full stall speed out of a converter is with a transbrake. Mine for example is a 5500 stall. Foot braking I see about 3200 rpm but on the trans brake it goes right to 5500-5600. The best way to buy a torque converter is to call a reputable converter company like Coan, PTC, BTE or Precision and have them build one for you. You give them every single specification on your car and they will build you the best converter for your car. It costs more but its well worth it. The junk that you can buy off the shelf from Summit or Jegs will work for you and be better than stock but will be far from optimal.

[Screemin3o2]

During converter stall, the impeller rotates but the turbine does not. The highest amount of stall is when the engine drives the impeller inside the converter at the max speed possible without moving the turbine. The engine RPM that this occurs is the stall speed. When the transmission is in drive and you put your foot on the brake and it is lower or at the stall speed and the turbine is not spinning, then the wheels are not turning. When turbine starts to move, that is when the wheels start to turn.

Torque converters are different between a fuild coupling because they multiply torque. They receive the highest amount of torque multiplication at the stall speed (when the engine is at its highest RPM without braking the tires loose).

Please correct me if I'm wrong because I lack more info on the high performance area on this. When you go to a higher stall converter, the converter is actually smaller than what the stock application is. They require more torque to turn the wheels, therefore they need a higher RPM to brake the tires loose. That is where you get more torque out of a higher stall speed, but smaller converter.

From my own thinking, as long as you have an unmodified vehicle, you should get the full stall speed out of the vehicle. Once you start giving your car more power and torque, the stall speed decreases.

[1slo5.0]

More horsepower will increase the stall speed. That is why you can buy a TCI converter that is advertised as a 3500 stall speed and it only does 2900 on the transbrake behind a mild small block but will do 3500+ behind a mild big block. Nitrous converters are built tighter with less stall because the instant horsepower of the nitrous will increase the stall speed by roughly 1000 rpm and sometimes more than that.

[Screemin3o2]

Originally Posted by Darrell More horsepower will increase the stall speed. That is why you can buy a TCI converter that is advertised as a 3500 stall speed and it only does 2900 on the transbrake behind a mild small block but will do 3500+ behind a mild big block. Nitrous converters are built tighter with less stall because the instant horsepower of the nitrous will increase the stall speed by roughly 1000 rpm and sometimes more than that.

Good to know, that's where I was a little vague on. But why wouldn't more torque from a larger engine be able to turn the turbine easier with less RPM? I was thinking since the engine creates more torque then it won't take as much to get the wheels to brake loose.

[reeds98gt]

THANKS FOR THE INFO

THE THE MODS I HAVE IN MIND DO YOU THINK I SHOULD CHANGE THE CONVERTER OR STAY WITH STOCK. THE CAR IS GOING TO BE MORE OF A DAILEY DRIVER. MAY BE PLAY AT THE TRACK SOME TIME.

TELL ME WHAT YOU THINK

[Bossman351]

Just a matter of personal opinion, I would shy away from a high stall if its a DD. A high stall converter creates a LOT of extra heat and friction and can be hard on a daily driven car especially in stop and go traffic. If you do go with a stall let me recomend that you use a good external automatic trans cooler.

[Screemin3o2]

I would stay stock for now until you get other things first. There are a few other things you can get over a converter.