Does the higher shift extension come from the transmission slipping? In other words if you lock up the converter during WOT to put more power to the wheels do you give up the higher shift extension?

 

Shift extension is a factor of the drop in gear ratio along with converter slippage.

in a manual transmission (assuming the clutch isn't slipping) a gear change will have a shift extension directly related to the gear ratio of the trans. So it may drop from 6000 to 3400 and climb linearly from there.

With a converter...the gear ratio may dictate the same 6000 to 3400 drop...but the converter will change the shift extension...it may "hang out" at 4400 rpm until the wheelspeed "catches up" to the converter then rpm will continue to rise again.

So...if you lock the converter during WOT...the shift extension will obviously be given up because the converter is no longer allowed to do its job and "slip"
And...as I've covered in another post quite recently...locking the converter at WOT is not always better. It won't always make you faster.

 

That's what I thought

 

Locking the torque converter clutch on the shift, will give you the biggest rpm drop, just like a manual transmission, compared to keeping it unlocked. I do not like the term "shift extension". The torque of the motor, the "gear ratio spread", diameter of the torque converter, the time it takes to complete a shift, from the beginning of the shift to the completion of the shift, STR of the specific torque converter, etc. Way too many variables. I don't know, who coined this "shift extension".

 

Shift extension is just a matter of how much rpm it drops...weird termonology but I just roll with it

for example...SBE guys trying to really wring out as much power as they can without hurting the rods want a small rpm drop. They want to go from 6600 in 2nd to 5800 in 3rd and let the converter just hang out and do work. Keeping the engine from bogging down helps save the rods.

 

Very very true :-)

 

So what dictates what a converters shift extension is? I'd assume a looser converter will have a higher shift extension.

 

see post #4

there's a boatload of variables
diameter
fin angle
stator blade count
converter charge pressure
weight
gear
rpm
cubes
power adder
etc etc etc