Everything I need to know for 5.3 or 6.0 Ls swap

[Christian Monfort]

I have a 1998 Chevy K2500 with a Vortec 5.7L and 4L80E. I’m hoping to mount the 5.3 to the 4L80 I heard there might be a problem with the torque converter mating. Also been reading forums and watching videos online on swapping a 5.3 in and it kind of keeps out stuff like will I be able to use the 5.3l’s ECM while still being able to keep gauges and other things working or will it need to run both ECMs? Is there a replacement stock 5.3 wiring harness? can I use the 5.7 fuel lines with a custom hose or adapter or would I need the 5.3 fuel lines as a replacement? can I keep the 5.7 Radiator or should I use a 5.3 radiator?

 

[Awest623]

Dunno about tc lining up, pretty sure there's an ls swap thread on here tho.

5.3 0411 ECM can run our gauges with the right programming.

Best place to get a harness would be the junk yard.

Fuel lines will be fine, runs on the same psi. May need a bigger fuel pump depending on your power output. The TRE performance 255lph kit would work great.

A radiator is a radiator. It'll work as long as you plumb it up.

 

[TexasRebel]

If you want to upgrade the radiator, I've heard some people using the 454 truck radiator.

Sent from my SM-N950U using Tapatalk

 

[Madscientist]

I have a 5.3 in my 97. You can use your stock radiator. It will cool just fine. I did upgrade mine but only because my stock one had a leak so i put the bigger in cause it was the same price but i used the stock for 6 months. Get yourself the harness from whatever donor motor and the computer, one with an auto. One with a 4l80 will save you just a little time in wire repin but to use a 4l60 harness is easy too. You will need to order a flexplate from a 2001 chevy 2500 with the 6.0 and 4l80e WITH the flexplate spacer and get the bolts too as they will be slightly longer. If you use a return style intake then you just need fuel line extensions/adapter and they will work. Returnless will use a Corvette ls1 fuel filter/pressure regulator that is a return unit built in and has the single feed coming out. Factory manifolds fit the exhaust with zero problems. gmt800 headers with with a little clearance. The stock ls computer will run your transmission. Your stock fuel pump will run a stock 4.8. 5.3 will run but will run out of fuel up top. I did a drop in aem 340lph e85 pump and its extremely quiet and feeds 500hp on stock fuel lines.

 

[Madscientist]

It a little bit of a hassle but you can hook up all of your factory gauges and i even have my cruze control hooked up too.

 

[stutaeng]

How do you like the 5.3 over the 5.7? I've got an ECSB '99 NBS with a tired 4.3. I was thinking about swapping a 5.3. I would really like to just go ahead and do a 4L80e while I have everything torn apart, as I have rebuild my 4L60 valve body...not sure yet.

OP, if you could find a '99 to '01 GMT 800 2500 Light Duty, that would be best. They came with 5.3 or 6.0 mated with 4L80e. May look at rear end also. They had 14 bolt semi float with disc brakes. They were only offered in regular cab or extended cab.

I have a 5.3 in my 97. You can use your stock radiator. It will cool just fine. I did upgrade mine but only because my stock one had a leak so i put the bigger in cause it was the same price but i used the stock for 6 months. Get yourself the harness from whatever donor motor and the computer, one with an auto. One with a 4l80 will save you just a little time in wire repin but to use a 4l60 harness is easy too. You will need to order a flexplate from a 2001 chevy 2500 with the 6.0 and 4l80e WITH the flexplate spacer and get the bolts too as they will be slightly longer. If you use a return style intake then you just need fuel line extensions/adapter and they will work. Returnless will use a Corvette ls1 fuel filter/pressure regulator that is a return unit built in and has the single feed coming out. Factory manifolds fit the exhaust with zero problems. gmt800 headers with with a little clearance. The stock ls computer will run your transmission. Your stock fuel pump will run a stock 4.8. 5.3 will run but will run out of fuel up top. I did a drop in aem 340lph e85 pump and its extremely quiet and feeds 500hp on stock fuel lines.

 

[Madscientist]

How do you like the 5.3 over the 5.7? I've got an ECSB '99 NBS with a tired 4.3. I was thinking about swapping a 5.3. I would really like to just go ahead and do a 4L80e while I have everything torn apart, as I have rebuild my 4L60 valve body...not sure yet.

OP, if you could find a '99 to '01 GMT 800 2500 Light Duty, that would be best. They came with 5.3 or 6.0 mated with 4L80e. May look at rear end also. They had 14 bolt semi float with disc brakes. They were only offered in regular cab or extended cab.

The 5.3 is in a completely different category than the 5.7. It has less torque under 2000 rpm than the 5.7 does and that is a big trade off but i have a big cam in mine with a built 4l60e with a 3000 stall and bolt ons. I also have 4.56 gears with a 33 inch tire. With this combo i have power everywhere and i get about 17mpg with it. The 6.0 is like the 5.7 down low and will pull way harder up top

 

[Madscientist]

I guess i never answered the question but i freaking love it! It is capable of making and holding serious power. Mine pulls very well up to 6500 and it pulls trailers very well too. I like fast stuff thou. I have a supercharger going on it soon.

 

[stutaeng]

The 5.3 is in a completely different category than the 5.7. It has less torque under 2000 rpm than the 5.7 does and that is a big trade off but i have a big cam in mine with a built 4l60e with a 3000 stall and bolt ons. I also have 4.56 gears with a 33 inch tire. With this combo i have power everywhere and i get about 17mpg with it. The 6.0 is like the 5.7 down low and will pull way harder up top

Ok, cool. I have 3.42 on the '99 and was thinking re-gearing also.

My other trucks are a '00 K3500 CCLB with 5.7 and GMT-800 2500 Suburban 2wd with LQ4. Both have 4L80 and 4.10s and are stock. The suburban feels a bit faster but the truck is heavier, so I cannot do an apples to apples comparison. But I like both engines combinations, just haven't driven a 5.3.

 

[89obsSB]

What all is needed to put my 5.3 out of my 2002 avalanche in my 97 ECSB. Will the 5.3 mount up to the 4l60 that came in the 97?