Is an LS3 a good route for a GMT800? My goal is 500whp for now with plenty of low end and daily driver manners, but a solid platform that I can take beyond that down the road. My current 5.3 has 200k on it..
Two things, an LS3 is Gen IV architecture. You have to decide if the electrical adaptation required is worth it as the GMT800s are Gen III.
Second, dropping in an LS3 crate motor is going to kill your bottom end. The camshaft was designed to move cars around fast, not trucks weighing 2000 pounds more. Most performance camshafts, even the "low lift" cams advertised for trucks, lose a substantial amount of lower end torque and gain it back higher in the rpm band. The is counter-productive for getting a big truck moving and of course, towing.
I read the posts of guys putting in "mild" cams in their trucks and then going with high stall converters and gears because they are now dogs off the line but scream above 4000 rpms. Who drives at 4000 rpms? In my daily travels, mine rarely sees 3000 rpms, the tune and 3.42 gear gets it up to the posted speed limits with little effort.
Just make sure the camshaft is designed to move a heavy truck, not a regular cab short bed that weighs as much as a Vette! And if going with forced induction, mild single pattern cams usually work best in those applications, letting the turbo or supercharger do most of the work when under boost.
