New to the LS game
1. Very expensive.
2. Gen 4, not the most user friendly.
3. Displacement matters very little with boost.
4. The rotating assembly isn't any stronger than any other floating rod LS.
The LS2 is a better choice, but still falls in the categories of the above.
The truck engines are the go-to for boost for several reasons.
1. Much cheaper
2. Far more abundant
3. Gen 3 engines everywhere.
4. Easier to tune/work with stock ECU.
5. Several displacements to choose from.
6. Replacement parts are everywhere.
7. Drive-by-cable made easy.
8. I can keep going.....
Unless you have zero budget, the truck motors are the go-to for boost. Even the smaller 4.8 has powered half a dozen cars into the 8s in the quarter mile on a stock long block. There are more 8-second stock shortblock 4.8s than 8-second stock shortblock LS3s.
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I throw an insane amount of boost at it, and it runs well enough that I drive it basically every day the sun is shining, even in the winter.
I've done similar with a $350 4.8.
If you want an aluminum block, the 5.3 is the way to go. There is a huge amount of material between the cylinders and you're not going to have strength issues. Anything bigger than the 5.3, I would probably have went with an iron block, especially since an aluminum 6.0 short block is typically twice what I spend on my entire engine.
I use a stock driver's side truck exhaust manifold with a KB Racing turbo manifold on the passenger side.
I've ran 30 PSI on my stock aluminum 5.3 long block.
Best trans for big power? Depends.
Track only? TH400 or powerglide. Lots of street/highway use? 4L80e.

