LS swap: pros and cons

[Zambo]

As long as I'm breaking down the humongous for paint, I've been considering swapping the gen 1 383 for an LS motor. I figure that it'll run a little better with less tweaking, respond to varying fuel octane and quality better, and get better mileage. How hard is the swap and is it worth it? What are some gotchas?

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[desertspeed]

While this doesn't help with your specific swap, and you may have already read it, here is some great background and technical information about the Gen III/IV (LSx) engines:

Part 1- http://www.pirate4x4.com/tech/billav...SPrimer/Part1/
Part 2- http://www.pirate4x4.com/tech/billav...SPrimer/Part2/

[Ramsey_ElWardani]

Just throw Fuel Injection on top of that thing and rejoice in a real SBC!

[Zambo]

Just throw Fuel Injection on top of that thing and rejoice in a real SBC!

Or that too. Anybody got any recs on good FI systems?

[Ol' Curmudgeon]

Just throw a TBI on it.

[BangShiftChad]

One great option if you don't want to do the swap is the new MSD Atomic EFI. It's super easy to install, works at any angle and through the roughest stuff, and doesn't require any real tuning experience. Plus you can install it on a Saturday morning. We've used them and tested them and they work great. They offer two kits that work at different power levels, and you don't have to replace any of your existing intake or air cleaner setup. Plumbing it is easy too, and it only has a few wires to hook up. We dig it.

As for the LS Swap, you can make more power with a tuned up 5.3 than you are getting from the 383 unless it is built with a really good set of cylinder heads. They are stupid easy to work on, but you will need headers, starter, bell housing, some clutch or torque converter parts depending on what trans you are running, and then of course the EFI setup. OR you can run it with a carb style intake and then run the Atomic on it too. There are lots of options, but these things make real power with a cnc port job on the heads, cam, intake, valvesprings, and you are good to go. Leave the stock pistons, rods, and crank in it and have a great engine that you can beat on.

[Zambo]

That Atomic unit looks pretty nice. Did you guys run a returnless fuel system or plumb a return line?

I've considered the 5.3 as well. Turnkey has a 400hp version but its like 7 or 8 grand I believe. I see 5.3 pullouts advertised complete for less than a grand but I don't know what it would take to get one up to the 400ish hp range. I like the 5.3 in my 03 Tahoe though, it pulls pretty good.

[Ol' Curmudgeon]

How often are you going to need in excess of 200 hp in a pre-runner? What's it weigh? A 1992 TBI SBC would push a 9C1 Caprice to 133 mph.

[allairch]

The ls based engines are great I run a ls6 in race truck cast 6.0 in prerunner and have a twin turbo in street t/a .They are very hard to beat a 5.3 with a good cam , headers and tune will make 400 @ flywheel with no prob.You could do engine for less than 1200. Then harness and headers

[Zambo]

How often are you going to need in excess of 200 hp in a pre-runner? What's it weigh? A 1992 TBI SBC would push a 9C1 Caprice to 133 mph.

Only to get out of trouble or to keep the front end up when necessary. The Humongous can get on top of some decent size stuff but i don't drive it super hard. The 383 I have now puts down about 300 torque to the rear wheels and that seems to be plenty. Would just like it to have some better efficiency (range) and quicker throttle response.