5.7 Rebuild or replace with a 5.3 LS?

I am new to the forum, so sorry if this has been discussed 1,000,000 times.

My 99 GMC 1500 Suburban is right at 300k miles. She does not smoke or knock or anything, but you can tell she is getting tired. I think she left the gate open and a bunch of her ponies escaped. I've put a good tune up on her and had the transmission rebuilt this year.

Given the cost of new trucks my wife and I have decided to keep it around. We have been getting about 16-17 mpg (stock with no cats) and a shocking 14.5 while pulling our camper (it's only 2700 pounds). I really want to keep the mpg as we love taking long camping trips. I do not ever see needing to tow more than 5-6k. I am trying to decide if I should have the 5.7 rebuilt or replaced with an LS. I figured this would be the place to get some opinions. Money is a factor in this decision also.

Looking this good I cannot see giving her up.

Do. A. Search.
This has been debated to death on this site, the pros and cons of both routes. Comes down to personal choice.

618 Syndicate said:

Do. A. Search.

Click to expand...

I did, and found several threads, but many seemed to be about making more power. Others did seem more on the practical side, but none seemed to mesh with what I am looking for. My main concern is moderate camper towing over long distances with the best possible mpg. Maybe I missed a few. I will look more.

IMO, stay with the 5.7. Yeah the LS's might make more power, but for what it costs to swap one, you could have a 5.7 rebuilt. I don't have any personal experience with an LS, but many of my friends do, and they all say the LS's are great, but none mentioned towing. I do have some that tow, and they all say a 454 tows better. I constantly have this debate with myself, but need to learn more bout LS's.

I was thinking the same I have a 96 k1500 suburban engine is knocking so contemplated engine ideas talked to a few people about the swap they did there's for the fuel economy and the extra power the 5.3 are great engines but for me I decided I would keep the 5.7. one reason because I like the original look. my suburban is in great condition and didn't want to change it up plus swapping a 5.3 can get a little costly with all the little pieces and changing wiring harness. Vs just rebuilding and putting 5.7 back in. Just depends on how much work you want to do a plug and play 5.7 or swap to a 5.3 and deal swapping out harnesses and getting all the original gauges to work takes a little extra plus pulling all the stuff out of engine bay you don't need anymore will look different as well Some people say is easy to do which I am sure it is others have a difficulty time just depends on how you are with it all.

I would say stick with the 5.7. This is just a personal opinion but I am tired of seeing LS swaps. To those of you that have done it good for you its just not my thing. I'd love to swap a 12v cummins into my 95 with the 6.5 but with what it would cost I could find a truck that already has one from the factory. I'm a believer in that if you want something with a certain option do the digging and find it factory installed. It will be less problems down the road. Again my 2 cents take it for what is worth.

I am probably wrong but i think a LS makes it power in a RPM range we don't normally run at in a stock drivetrain?

WillH said:

I did, and found several threads, but many seemed to be about making more power. Others did seem more on the practical side, but none seemed to mesh with what I am looking for. My main concern is moderate camper towing over long distances with the best possible mpg. Maybe I missed a few. I will look more.

Click to expand...

If your main concern is towing over distances with good fuel economy, go buy a modern diesel. You can LS swap or rebuild the burb, and it'll tow fine, but it'll never get the mileage of a diesel. There are notorious LS haters here, and several swap fans as well and you'll get opinions from both sides. But what you do comes down to personal choice. That should be guided by your intended purpose and budget.

If I could get a rebuilt 6.0 installed and running (with all oem gauges etc functioning) for the same price as rebuilding the 5.7, I might pick the 6.0. Otherwise I say rebuilt 5.7. Fresh is good.

I would not pick a 5.3 over a 5.7, unless force feeding the 5.3.

Rebuild or crate motor 5.7L FTW!