Ok, I must be MR or something because I have read up on torque converters and my brain is just not understanding what they do precisely. I understand how they work but not exactly what they do. Let's just use a converter with a 3200 stall for example. Does this mean the converter isn't sending power to the wheels until my engine reaches 3200 rpms? That doesn't make sense to me but that's the impression i'm getting.

 

If you sat there with a 3200 stall and nailed the gas your engine would almost instantly jump to 3200rpms. It's like it's in neutral until it hits 3200rpms. It just brings the car to it's power band. Basically like revving up to 3200rpms and dumping the clutch in a manual.

 

and once you get up to a certain speed (like 35mph) the TC locks up so that its sending power to the wheels no matter what the rpm right?

 

stall speed means this:its the rpm that the wheels either turn or the engine stalls....its can slip nomo...up to that rpm it slips less and less until it reaches its stall speed...then either the wheels move or the engine stalls.

 

The stock torque converter is 1800 rpm's and 1.6 STR. 1800 is the rpm that the converter flashes to when you punch the gas. STR = stall torque ratio and the higher the number the harder the converter hits the rear tires. 1.6 is considered relatively mild and 3.0 is considered a monster. Most 3200 stalls are in the 2.0 - 2.2 STR range.

I mention the above only as a comparison to what the aftermarket converter feels like. So when you punch the gas on a stock torque converter you'll get a little spin and see the rpm's jump to 1800 and climb from there. Now put a 3200 stall with a 2.2 STR in that same car and the car feels way different.

Now when you punch the gas the stall flashes to 3200 rpm's and you climb from there instead of 1800. This makes the car feels alot faster because the LS1 motor makes alot more torque at 3200 rpm's then it does at 1800. Plus a 2.2 STR puts alot more torque to the wheels so when you hit it you'll feel a much more violent type of "pinning you back in your seat" (big fun). Unfortunately this STR will also roast street tires so many people switch to drag radials. But all of this talk is about when we go WoT, what about normal driving?

With anything bigger then say a 3000 stall you will notice it takes a little more gas to get moving off a light or in reverse. Not a lot but a little. You'll also notice that while under say 40 mph the car runs at slightly higher rpm's. I used to be at 1000 rpm's at 30 mph but with a 3500 stall I now will be at 1400 rpm's. After 35-40 mph the converter should "lock up" and the rpm's will drop back down to normal. Not a big deal. But off a light I do have to give more pedal to get moving which is referred to as "looseness". A 3000 stall feels pretty tight, A 3200 stall feels just a little tiny bit loose, A 3500 stall feels mildly loose, 3800 stalls are definately loose and 4000+ would be very loose on a internally stock motor with stock gears.

So basically you have a good and bad trade off. The higher stalls allow you to flash above the lower rpm ranges where you make less torque, allows the car to be a good .5 faster in the quarter mile, fixes that damn 35 mph dead spot and makes launching on sticky tires an extremly fun experience. But it does all that at the expense of making the car feel a little more sluggish at part throttle, higher rpm's in the city causeing less mpg and it generates more heat on the transmission. Since heat is the number one killer of 4L60E'S everyone recommends a 24K transmission cooler be installed at the same time as any 3000+ stall torque converter.

All that being said, I would never go back to driving a car with a stock torque converter again. I absolutely love this TCI 3500 stall

 

I had a hard time understanding what they do / how they work too

This cleared it up for me alot hope it can help you

http://auto.howstuffworks.com/torque-converter.htm

 

If you want some good info go to Yanks website. It has some really good info on there.

Plus you have to remember there stall rate (3200rpm or what ever) can actually mean several things. It's all explained on Yanks site however. If you're not sure what you need, have a word with them and exlain (realisticaly) what you want from the car and what it IS going to be used for. They will then be able to guide you to what is most suitable.

Jsst remember different companies rate things differently though, so a 3200 frpm one place may not be the same as 3200 from another.