As time rolls on, more and more people will likely be interested in swapping out their older motors for a more modern LS engine. The benefits to fuel economy and choice, horsepower, and torque--not to mention the easy of a Fuel Injected start--are innumerable. There are a ton of resources around the Internet on this very topic, and that is the problem--it's overwhelming!
So, I figured I'd start this thread on resources for swapping to an LS motor. Keep in mind, I have not done this myself but I plan to--and here I will simply share the information I have collected. This is FAR from everything and some of it will be plain wrong--so please lets chat about this and build a resource for other Impala owners looking to do this swap.
Starting from the rear to the front end:
1) Fuel - I didn't know this but your stock fuel system won't handle an LS swap. LS motors require 58 PSI in the fuel line, which may necessitate an upgraded line. The stock tank needs a bit of tinkering too--in order to ensure the fuel PSI is maintained, you will need a tank with baffles in it to prevent the fuel from sloshing away from the in-tank pump during acceleration, cornering, and stopping. I have read that in-line pumps are not ideal for LS motors.
2) Drive Shaft - You may need to get it shortened.
3) Transmission - You can get a kit that will bolt up any old small block chevy transmission to an LS motor. Or, you can use the stock transmissions. This is an area where I'm a bit weak.
3) Electronics - You'll need to either re-wire the factory harness from the LS donor, or you'll need to purchase a specially designed wiring loom from a place like Painless Autowire. In addition, there are all kinds of emissions issues and anti-theft devices built into the computer on the LS motor, which you will need to have reprogrammed. There are plenty of places and ways to do this programming but it will have to happen.
4) The Engine - We are working with big cars, but even still, space may be an issue. The oil pan can sometimes hit the crossmember, and you'll need to replace it with a different one. GM does make pans that will fit, and there are plenty of aftermarket options. Additionally, the engine mounts on LS motors are different then SBC (small block chevys) and BBC (5 points if you can figure that out :P) and so a specific conversion kit is necessary to bolt it in. Finally, there are accessories on the front end that all connect to a serpentine belt that will change if the engine will fit in your application.
In addition, there are quite a few variations on the LS motor for you to choose from. Seems that the best place is an automobile wreckers, but selecting your specific engine is probably best done with the help of Wikipedia:
And a handy guide for what these engines put out:
There are a LOT more details then what I've covered, but let's pool our knowledge a bit to provide some guidance.
Where can one get conversion kits? Baffled fuel tanks? Has anyone done a swap and if so what kinds of mods did you have to make to your car?