I have a Yank SS4000 (advertised as 4000 Stall, 2.60:1 STR)
It was previously behind my LE H/C 350 LT1
The stall worked great with that setup at the track and seems very streetable.
I did not dyno the car after the SS4000 install (removed a 3200 Protorque)

This year, I installed a forged 383 with a much larger cam and bigger heads.
When we sat it on the dyno to tune, we found that the converter was slipping about 35% unlocked VS locked. (300rwhp VS 461)
That seems a little extreme, even for a 2.6:1
When I drive it on the street, it fees MUCH looser than it did with the 350.

When I asked another SS4000 owner about it, he suggested that he had
only seen about 10% loss behind his cammed 396.

How would I go about diagnosing/repairing the issue?
Or is this just a symptom of having put the converter behind a motor with more torque?

 

If it's an actual measured 35% then call yank and tell them what it's doing and ask them if they can cure it.

My PT4000 was slipping too much to suit me so I set it up with them to pull it apart and tighten it up. Sent it in and they found that it had broken parts in it as well. $300 plus shipping later and it's perfect.

 

Didn't have much luck with Yank support via email or PM .. I'll try calling.
This thing is less than 2years old .. it should still be under warranty.

 

I believe the more powerful the motor, the higher a converter will stall at.

 

Yes that's true but stall speed isn't slip at speed. After the rpms get higher than the stall speed of the converter it shouldn't slip more than 10-15%.

 

Oh I see what you mean, might it be the transmission clutches slipping?

 

The issue is locked VS unlocked, so we know it's the converter.
If it were anything else, locking up the verter early wouldn't have made a difference.

 

https://www.camaroz28.com/forums/sho...d.php?t=415639

Rich