Stall Converters... [Archive] - Cherokee SRT8 Forum

: Stall Converters...


FastJeepSRT8
11-30-2006, 01:28 AM
I've heard some mention of stall converters here. What are they and how do they affect performance? Is this a mod worth while or should I be focusing on other areas first? Thanks.

ekool
11-30-2006, 01:53 AM
A "stall converter" is usually refered to as a "torque converter" -- its basicly a device that sits between the crank and the transmission and it allows the car to "rev" to a certain RPM and keep the engine in the power band. There are different stalls (read: the range that the torque converter allows the motor to "flash" to before the torque converter starts transferring the power to the transmission) and generally speaking the higher the RPM, the quicker the acceleration as it puts you into the powerband more often then a lower stall converter.

Imagine if you punch your Jeep now at a low RPM and it doesnt necessarily kick down a gear.. you might be at 1500 RPM and the motor is lugging a bit... imagine if the converter kicked that up to 3500 RPM's instead.

Its a crude description, but you get the idea. Basicly, a torque converter is one of the best things you can do to an automatic tranny equipped vehicle that doesnt actually increase the power at all :)

Here's a good wikipedia article on it:
http://en.wikipedia.org/wiki/Torque_converter

FastJeepSRT8
11-30-2006, 02:06 AM
Nice link, thanks ekool. So am I to understand that if you upgrade your converter then you're replacing the entire unit? If you do this how will this affect overall performance on the low and high end? And lastly could the torque converters in our Jeeps be the source of the downshift problems in the 30mph range? I have that problem in mine similar to what you just explained you punch it and the rpm's aren't high enough and it doesn't shift any lower so you just muddle along until the rpm's come up.

gculver
11-30-2006, 09:08 AM
Nice link, thanks ekool. So am I to understand that if you upgrade your converter then you're replacing the entire unit? If you do this how will this affect overall performance on the low and high end? And lastly could the torque converters in our Jeeps be the source of the downshift problems in the 30mph range? I have that problem in mine similar to what you just explained you punch it and the rpm's aren't high enough and it doesn't shift any lower so you just muddle along until the rpm's come up.
If you are looking towards the converter to fix the inherent ECM,TCM shortcomings, it will not. Downshifts are dictated by throttle position, vehicle speeds, torque load and rpm.Reducing the torque managment programming is the only real solution. Dont get me wrong converters would net you a reduction in 1/4 mile time if thats what your after(working within the powerband of the cam/motor) but your street driveability will suffer a little,to much stall speed and it feels like the tranny is slipping until the converters stall speed is reached. Tried to keep it simple,hope this helps.