Well the nitrous has certainly solved some of my 3.0 slow issues, BUT it still isn't fast enough off the line... yet. When I hit the gas the truck jumps forward, then the 33" tires slow it down, once I hit 3000 RPM, the nitrous hits and off I go.

I'm looking to get a stall converter (2500 RPM) coupled with posi so that I can hit the switch off the line. The only problem I can forsee, (other then breaking things from immense torqe) is that the computer might give some error codes b/c the input and output speeds of the stall converter will no longer be what they were. Anyone have any experiance with this, or would a programmer solve these issues? Thanks in advance,

- Matthew - KE5AFU

 

The stall RPM of the stock converter is over 2500 already -- you want to drop it?

 

Hmm, maybe I'm not being specific enough. Or I misunderstand what it does. To my knowledge there are two different types of converters, locked and unlocked. Dunno which does which. But one will spin freely until a specific RPM range and then gear up and engage. Hence I can be idling @ 2000-2500 rpm @ light then floor it and immediatly be @ 3000 (safe range for nitrous). Right now I hit the gas and the RPM's surge to 2700 then drop back down as truck starts to move, I'm trying to get out of the hole faster essentially and was told that this is what I needed to do.
I may have the RPM ranges wrong, but that's why I'm asking on here before doing.

 

You need to read up on torque converters... Your understanding is flawed.
If I find a good site I'll edit in a link..
As I dont feel like typing out a page... (any takers out there?)

 

The basic stall speed is where the RPMS stop climbing with the torque converter output shaft not rotating. There is a different set of circumstances at play when the truck starts rolling because now real "torque multiplication" is occuring and the input shaft slows down. That is highly variable and difficult to measure.

You will not get the vehcile to stand still unless your foot is on the brake. "Lock up" torque converters have a clutch to "bypass" the torque converter and directly connect the input and output shafts.

Read up as Rand suggested. Still, there may be a specific way that racing converters are specified that differs from the way converters are normally described that we're not aware of, and that may be something you can find out and explain to US!

 

If you have an auto, power break, if you have a stick, feather the clutch, you'll only make things worse with a stall converter in a truck like yours.

 

high stalls can be terrible on the street or rock crawling. idealy u wanna 2500 or so rpm stall for street. 3000-4500 is great for drag racing, hill climbing, mud bogging...anywhere u are gunna spend most of ur time at higher rpms...but terrible on the street.

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

http://www.fuelinjection.net/newslet...all_speed.html

 

Also if you were to go to a higher stall I would get one with anti-ballooning plates. The anti-ballooning plates reinforce the toque converter's walls when used in power adder applications. For your power level it really isn't needed, but if you've ever seen one (torque converter) blow at the track, you would invest in them.

As was stated though I wouldn't do this if this is your daily driver. The number one killer of automatic transmissions is excessive heat, and a higher stall converter just adds tons of heat when it is "dragging" (below its recommended stall speed).

Just some food for thought.

 

Your factory converter has a clutch that can "lock" the converter when commanded by the PCM. This effectively takes the torque converter out of the picture by reducing its slippage to zero. The torque converter clutch is generally not applied during WOT launches in 1st gear. It is typically used at lighter throttle cruise for fuel economy or in manual 3rd or 4th for transmission temperature reduction while towing.

I think you are talking about a high-stall converter which allows the RPMs to rise higher at launch. This is useful for launching a vehicle with an engine that is tuned to make the bulk of its power at higher RPM but is weak at lower RPM. As noted above, it is a poor choice for general street and off road use.

The shop manual lists the stall speed of a factory 3.0L/5R44E TC as 2825~3400, which should be plenty high. Perhaps what you really need is to regear to compensate for the 33" tires.