If I put a supercharger kit on my truck I want to upgrade the trans. While the 4L80e is a stout unit, mine has 258k on the original in a 7000 pound truck. Even just 50% more power puts me over the 440 lb-ft input limit is 4L80e is rated at. If I wanted to upgrade the transmission without rebuilding it, what upgrades do y'all recommend? I know there are quite a few threads, but most talk about rebuilding. Thanks in advance!
Personally I wouldn't worry about it at all. There are lots of people putting huge HP/TQ to the tires (really huge, like 1000 HP) through relatively stock junkyard 4L80Es. If you really want to do something I'd install a TransGo HD2 shift kit (minus one specific part, link to that below, top of the page) and call it good. https://sites.google.com/site/sloppywiki/everything-ls/4l80e-info Just for laughs, here's an example of the type of setup I was talking about. Turbo LQ4, 250K mile junkyard 4L80E with a TransGo HD2.
Here's an uncut hour long video of that same guy with the Colorado installing a TransGo HD2 in a 4L80E.
