3 GM 6.5's later now I have a Cummins

[b1jetmech]

The 4L80E isn't all that strong. The inline engines tend to bring the weekness's out in em. There main weekness though IS the OD unit that GM added on.

The only thing I hear breaking on th400 and 4l80e on high horse and torque applications is the case. Adding an aluminum pan helps out. A TH400/4L80e can be built to handle 1400 HP. that's not far behind an Allison.

Nelson Racing engines put 4l80E's behind their 1,500 plus HP twin turbo engines.

TCI builds a 6 speed version of the 4L80 that handles 850 hp right out of the box. They didn't do any mods to the rotating assembly other then adding more clutches and modifying a planet assembly for a lower ratio in first. They doubles the over drive clutch pack from 3 to 6.

Chase