Torque converter question

MidTexCuda said

dumb question but what happens in a transbrake application when the stall speed is c lose to the launch speed? Does it work the same as dumping a clutch? What is the reason for running a high stall in a t-brake car? say you launch at 5k on a 5k verter. why not just use a lower stall and maybe larger case say 10" or 11" vs. a 7" or 8"?

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Your reference to the stall speed being close to the launch speed is a non issue. Using a high stall converter gets the rpm up in the engines power band so it takes off harder. The trans brake acts similar to dumping the clutch but also has the advantage of holding the car in place (a t-brake locks the trans in drive and reverse at the same time) on the starting line and letting go of a button is a quicker reaction than letting off the brake and flooring the accelerator.

If you use a lower stall converter you engine will not be in it's power band on take off so the car will be slower. You cannot get a 11" converter to stall at 5k. Doubt anyone could get a 10" to stall that high. Also keep in mind the mass your spinning with a 11 or 12" clutch vs. a 7 or 8. That mass may help the launch (if the stall speed were the same) but it sucks up HP

Think of it like this. Say your driving a stick shift car and you stop and rev it to 2500 rpm and dump the clutch then you stop again and rev it to 4500 and dump the clutch. Which rpm is it going to take off harder at? The 4500 of course. This assumes you have traction available to take off at a 4500 drop

Hope that helps