Hi. I just bought a 91 firebird with the 3.1l. I bought the car because I am intending on doing this swap. I'm 18 and have never done anything like this before but I will have tons of help from people I know. Anyways I am thinking about buying a semi low mile 5.3 from a local junkyard. I would like to also get a ls6 cam/intake for it. I'm hoping this will get me to 400hp? And my last question's are will I be able to use my stock driveshaft with the 4l60e trans and also what motor mounts should I use. And will my stock fuel pump be fine. And if people have done this swap before, is there any other common issues that people run into with this setup. Thanks!

 

Unfortunately those components will only net you about 350hp on an LM7. The truck motor doesn't have the the compression, head flow, or displacement of the LS6 so it won't make the same power with just those parts.

 

SilverChicken is right, the LS1/6 cam and intake won't be enough to make 400hp on it's own, however I'd check out the Hot Rod website.
If you want 400 hp from a 5.3, check out Hot Rod and Car Craft websites. I can't remember which one, but this weekend I read about a fairly simple build on a 5.3 that made over 400 hp N/A.
Most of your questions that you already asked will be in the sticky thread below. But here's a quick answer to your questions, no your stock fuel pump will not be enough. There is a significant pressure difference between the two motors. Your driveshaft should fit, if it's a 700.

https://www.thirdgen.org/forums/ltx-...third-gen.html

Also, if you want more responses, perhaps asking a moderator to move it into the LSX part of the engine swap forum could help.

 

Thanks for the input! I'll go do some more research then!

 

A build like this would get you around 400 horsepower at the wheels:

http://www.camaroperformers.com/cama...aro-ls-engine/

Not sure if you meant 400BHP or 400WHP...

 

Alright did a lot of the research. It answered almost every question I have had so far! Thanks soo much for the help!