I was just wondering how much HP that a 4L80e can rob? Has anyone gone from 6speed to a 80 and have any true dyno numbers.

 

Right at 50 according to a non load bearing dyno.

 

With or without the converter locked? I suspect that is with the converter unlocked and it will be more around 30 with the converter locked.
I'm guessing, so please confirm.

The approximate guideline is that a manual trans car loses 10% of the HP in the drivetrain, while an automatic trans car loses 20% of the HP with a non-locking converter. I'm guessing a loss of 15% with a locking converter.

Remember that only triple-disk converters can reliably be locked at WOT.

 

Unlocked