Im planning on rebuilding my trans here soon and im trying to find a heavy duty torque converter. I have a 5.4 with the 4r70w and im pretty sure the stock stall is 1200. I have a buddy that can get me a new HD Dacco torque converter for cheap but they only go as low as 1600. Im wondering if that 400 rpm difference will shorten my powerband too much. What do you guys think?

Thanks
Ccdline73

 

the stock stall converter is 2000rpm.

i have a circle D 2400 stall and i love it!

 

Well the guys at Dacco were telling me it was 1200. So 1600 should be fine either way? Not to high or low?

 

If they go as low as 1600, isn't something closer to stock better? Assuming 2000 is stock, and you seem to want to keep that, get something closest to whatever stock truly is.

 

Do you want a converter hat is more robust than stock? Or do you want one that produces more power by having a higher torque multiplication number?

 

Now im not sure what the stock stall is and I can't find anything online that says what the stock stall is. I would like a beefier tq converter but id also like the higher tq multiplication. I've also been told that the lower rpm the better the mpg and the trans fluid stays cooler. Somebody please straighten me out cuz im starting to get mixed up

 

Reread this thread, you have been told what the stock stall speed is..........post #2.

 

To multiply the torque the converter has to slip. That is not conducive to fuel economy. That is why the convert has a lock up system. That keeps the converter from slipping. Your engine is designed to produce 90% of the maximum torque at 2000 rpm. The stock converter is plenty robust and stalls at an optimum rpm for fuel economy. If you want more power get a higher stall stall converter.

 

Like I said before, Dacco told me the stall speed is 1200 but others seem to think it's 2000 so that is why I was getting confused

 

I've never seen a converter that low. 2k is around what most stock converters are on any vehicle.

 

There is more to all this than meets the eye so to speak.
There are differences in stall between the 4.2, 4.6 and 5.4L engine combinations.
The usual stall is in the 1500/1600 range.
Where the truck 'begins' to move freely with throttle applied is not the stall speed. On my truck the converter is so tight that the truck will move by it's self without anymore than just sleight off idle application from hot idle of 750 rpm.
.
The stall point of the converter in any particular vehicle is the point the engine RPM is limited too, at full throttle, with the brakes applied, to keep the truck from moving. This can be higher or lower depending on the torque the motor puts out.
Then there is 'flash' stall that loads the converter with sudden application of full throttle that can be yet a different variation reaction to total torque produced..
Performance overall is dependent on weight, gear ratio, transmission gearing in lower gears, engine torque and converter characteristics.
There is more yet to this;
The motor's torque curve. Where does it begin to build at a more rapid rate?
That answer is in the 2100 RPM range +.
A better converter to hook up and get the motor into this torque curve faster is this range or slightly higher to make a worthwhile improvement for street use.
Does it shorten the torque band, not much when looked at from a street performance point of view but may cause more slip below it's stall point area. It depends on the way the converter was built internally.
The lockup feature accounts for slip in OD except when forced out of lockup or any reason then you see the slip values as the change in RPM.
The increased torque comes from this sequence; converter stall raised allows the engine to enter it's higher torque producing curve rpm, converter multiplication increases it more, the first gear ratio multiples it more plus the multiplication of the rear gear ratio.
When you increase this multiplication 'stacking' it allows the motor to enter it's higher part of torque band at a faster rate, the results is faster acceleration rate per throttle application to move the vehicle weight.
.
Surprise; horse power does not move any vehicle, torque produced by the motor does all the work at any speed.
Horse Power is only a mathematical computation derived from Torque and RPM.
Lastly, max engine torque occurs at about 3250 rpm well above converter lockup. The farther up the stall is brought toward this max. the more torque is built and the 'shorter' the useful high torque band becomes.
As the torque rpm goes past the max, upshifting must take place to drop back into the lower end of the band to build again to the next shift point.
Good luck.

 

2000 stall is what your truck came with from the factory as others have stated so I wouldn't go any lower than that.

I ran a 4000 stall in my Camaro from Circle D, it was too much fun.