Can someone explain to me how a stall converter works? A seasoned drag racer told me I should run a 3000 stall converter in my stock GT to get a better launch. Any comments?

 

Seasoned?
Well before electronics took over that would be true.
That is why he said that. Old school. New school... computer tune!!!
Don W knows more than I do about this. Ask him.

 

It's actually the stall speed of your torque converter. From the factory they're around 2k. A higher stall would allow you to launch the car at a higher RPM to take advantage of more torque. That's the quick answer.

 

I am guessing it would be pointless to use a stall converter if you are using street radials.

 

My 07 GT is a daily driver and weekend warrior, and I have a very big stall converter (flashes to 4,500 rpm's). Mashing the throttle means flashing the converter right to peak torque and tire spin with the factory rubber in 1st and 2nd gears (and that was before adding the supercharger). I absolutely love that the car can be at peak torque instantly with the converter! At the dragstrip, I use drag radials which hook up great, even with the 4.10 gears and big stall converter.

Back to the original question, though. My launches at the dragstrip (60' times) improved .25 second (on average) after installing the stall converter, which made it one heckuva great modification for the money spent. Daily driving is so much more entertaining, as well, in all gears.

Word to the wise, though. For a daily driver, make sure that you pick a stall converter that retains the lock-up mode for drive and overdrive to keep fuel economy reasonable on the highway. The lock-up style converters typically cost a little more, but are worth it for a street car. 1st, 2nd, and 3rd gears do not lock-up with the factory converter or the aftermarket converters, so they are very loose (flash easily) and eager to rev so city fuel economy will suffer a bit with a big converter. I lost about 3 mpg in town, but highway mileage stayed exactly the same as I bought a lock-up style converter.

 

By the way, if you want to hear what my GT sounds like with a big stall converter, I've included an in-car video I shot before the supercharger was installed. The converter was flashing to 3,800 rpm's then. The beginning of the vid I was just taking off mildly onto the street (you'll notice very little drop in rpm's between gears). At the stop light I hammered it (you'll notice instant rev to 3,800 rpm's and beyond as the tires went up in smoke in 1st and 2nd gears before I let off due to oncoming traffic)...

http://s294.photobucket.com/albums/m...07GTLaunch.flv