regardless. If he wants help all he has to do is reply. We ask why when it's not a good idea to do. Trying to help him. If he has a good reason then all he's gotta do is get back online and reply.

Either that or he's Trollin.

 

I know ya'll will think its a stupid idea, but i have an 03 2500 Suburban with the 6.0, has about 220,xxx miles on it, pushing around 300 hp, but i have a 5.3 out of an 04 silverado, cammed, built pretty well, pushing about 410 hp, this is the only reason I'm wanting to swap to a 5.3 instead of keeping the 6.0. The 5.3 also only has 144,xxx miles on it. I planned on keeping the 4l80 Trans, just need to know what I need to get the 5.3 to work in place of the 6.0.

 

I don't know anything about cams, duration, LSA, etc., so I can't comment on your specific swap application from a power perspective.

But the 5.3 will swap into where the 6.0 is. Just swap over the flexplate from the 6.0. Do your segment swap and/or tune and off you go. Your suburban has 3.73 or 4.10. Not sure on torque converter stall speed. That all has to work together. 🤷

I drive an 06 Suburban 6.0/4.10, which is bone stock. IIRC the SUV 2500s were rated at 325 HP, not sure why? Probably had to do with derating the 2500HD trucks because they knew they were going to live hard lives? I've never really gotten a straight answer on that online.

Anyways, "I" would keep the 6.0. I know that's not what you are asking, so that's just my opinion. I suppose you can try it. If it doesn't work to your taste, swap it back? Or keep the swap. The nice things about these engines is that are pretty much all interchangeable.

 

04 truck engine into an 03 SUV is an easy long block swap with the caveats noted above.
good luck. i'd just expect it to work harder & get worse mileage if that 5.3's power is all mid & high rpm because the LQ4's low torque is what that suburban needs.

 

5.3L is going to be a dog compared to the stock 6.0L.