Looks like it's time for the "old man" to give another one of his "101 lessons"

stall speed is the engine RPM level at which the torque converter "locks" and overcomes whatever resistance is present to turn the wheels. Weight affects the stall speed because it changes the amount of resistance that the converter has to overcome.A more powerful engine also lowers stall speed because increasing engine power has essentially the same effect as lowering a vehicle's weight.
One of the worst mistakes you can make is to buy a converter with a stall speed that is too high. This usually results in a car that is not only much slower than it used to be, but also gets horrendous fuel economy and eats transmissions. This is because the converter is slipping all of the time, robbing power from your engine. That absorbed power is passed along as heat to the rest of the transmission.
An important factor to consider when selecting a torque converter is the camshaft. The camshaft basically dictates the RPM level at which the engine will produce it's peak torque, which will in turn dictate the optimum stall speed. If your camshaft has a duration of 220-230 degrees (@ 0.050" lift) or more, you definitely want to think about a higher stall speed converter, probably about 1000 RPM over stock, because the engine will probably make peak torque at well over 2000 RPM.
Performance Torque Converters are usually designed to accelerate more aggressively than stock, so an aftermarket converter with the exact same stall speed rating as stock will often be much more responsive than the stock unit. Especially in our case, because the stock converter in our trannies is considered one of our trucks most serious Achilles' Heel. You just want to be very careful about the stall speed that you select.
If you've ever been to the drag strip, you have probably noticed that the cars rev way up before the light turns green - this is because most racing engines don't make substantial power until they are spinning over 3000 RPM. Now when I say "streetable", think of how it would suck, if you had to rev to 3000 RPM+ at every intersection before your torque converter fully engaged!

By the way, I cannot take credit for 80% of this post, as some paragraphs are "cut & pastes" from a couple of sites, but I hope it helps...

 

so you kinda unload the engine by letting it freewheel a little bit so that it can rev up faster?

 

Sort of. If I understand correctly, it's kind of like holding in the clutch until you rev the engine to the stall speed, then dumping the clutch. You basically have to hit the stall speed (and keep it there or higher) before the torque converter fully engages, thereby transferring power to the transmission.

As HammerZ71 stated, if you buy a converter with a stall speed too high, say 3000 RPM, you'll be losing power anytime the engine isn't revving that high. It's basically like you're feathering the clutch the whole time you are driving, which creates heat and burns up the converter and the tranny.

 

how hard is it to put a new torque convertor in? Can you loosen up the tranny enough to put one in or do you have to take it out?

 

Thanks again Hammer for the info, I'll check out that web site. As for high stall converters, be aware that high stall equals high heat! A killer of everything mechanical! High stall converters are great for drag race applications where you want the converter to lock up right in the middle of your power band so that you get full torque when you launch! The downside is that they slip like hell outside the power band sending your transmission temp into the stratosphere! 99% of your normal driving habits will fall well below your maximum torque / HP range so 99% of the time a high stall coverter will be slipping away boiling your trans fluid.

 

Proof positive.

The 09 RT has an "upgraded" converter. No other mods but a mild cat back... It will get to 60 in under 6 seconds. Take a similar 09 and I guarantee it will be mid 6s.

http://www.pickuptrucks.com/html/200...m-1500-rt.html

If I get a 4th Gen that will be my first, well OK, one of my mods.

 

so if i wanted a lowe end torque machine, i'd wat to stick to the low stall speed, but switch out this crap *** stock convertor, right?

 

YEP! Hey you stole my terminator pic! GIT!

 

Actually Xfee, you are taking a page out of my book. I've got the CAI and LT Headers because the Cam I'm doing next needs them and will be a low end torque monster cam (KRC 210) and to get ALL that power and low end torque to the ground, it's gonna be a much higher end, after market Torque Converter, but by "higher end" I am in no way talking "higher stall"...

 

Where does one look in order to purchase a high end torque converter? KRC performance, Air Ram, Moe's performance?