5.7 vortec or 5.3LS?

[Supercharged111]

Um, no you can't bore a a 305 to a 350. Take a 350, bore it .030 over and put in a 3.75" crank, then you have a 383. Can do that to a 305 too, makes a 335 IIRC.

I'm not sure on the 305 wall thickness, but in the LS world a 5.3 can be bored to a 5.7.

 

[BeXtreme]

Um, no you can't bore a a 305 to a 350. Take a 350, bore it .030 over and put in a 3.75" crank, then you have a 383. Can do that to a 305 too, makes a 335 IIRC.

Yeah, sorry.. total brain fart. I'm not sure what I was thinking about, but you can't bore a 305 block over that much. If you want to go 350, just get a donor. If it is in decent shape just run it as-is. If you need to do any work to it, you might as well just put in a 383 stroker kit. For it to be a true 383, it will need to be .030' over as rat stated.

 

[stutaeng]

Yeah, don't mess around with the 5.0L. Seems they were the worst, underpowered V8, carryover from the 80s when they sucked the power of the V8. 190 HP! As you said, nobody wants them, for good reason.

The 6.0LS/4L80e is probably the best combination out there at a very economical price. At least around here they are around $2200-2500. Seems expensive, but you get a ready to drop-in power train, complete with wiring harness and ECU. If you can figure out the wiring, you won't regret it. 300-325 HP/380 TQ. Not too bad for out of box performance. Mods can you you much higher, but I'm taking stock vs stock, so we'll use that.

When compared to a full rebuild cost of your engine, it makes that $2500 price very affordable, and you step up the the HD transmission. I've got a few 2500 series GMT 800 SUVs LQ4 6.0 (a 2wd and a 4x4) and I'm very pleased with that combination. Both have 4.10 gears. Plenty of power, smooth and very reliable. Really no complaints.

Next option is a 5.3LS. Somewhere around 315 HP/320 TQ. I've got another GMT 800 1500 that I swapped a 5.3 LM7/4L80e from the original 4.3/4L60e. I got to say, the 5.3/4L80e is another great option since you have a 1500. Mine has 3.42. In a lighter truck the 5.3 is just fine with 3.42/3.73. That engine I got for like $450 or so, complete with everything. HP/$ ratio, this probably the best bang for your buck.

Last truck I own is a GMT 400 K3500 with the 5.7/4L80e/4.10. 255 HP/330 TQ. It's plenty torque-y off the line, but just doesn't have the mid to high range power. It's fine, but my experience with the SBC is they can have issues with distributors, missfires, and those spider injectors, especially after the 200K mark...not a fan of that system, but some guys like it. My truck is not a daily, so the SBC is just fine. I only use it like once a month at most. I would pick the 6.0 over the 5.7 if I needed a reliable HD truck though.

At some point I considered swapping a 5.7 Vortec in my 1500. You can get rid of the spider injectors, but requires a "Marine" intake. When I looked, the very few of those intakes that I found were like $600-$800 alone. I said screw that. You can also do a distributor delete on the SBC, but it's a lot of work. Same for the 0411 upgrade. Just do an LS and automatically get all of that, for way cheaper and less headaches.

Note all trucks I mentioned have the 4L80e. It's a great transmission for heavy duty use.

Generally, the LS is just a more advanced engine, there was more engineering and research used on it than the earlier Generation I/II SBC. It has distributor-less ignition (individual coil packs), fuel rail that makes injector diagnosis easier, and the ECU is also much more advanced with ignition timing thanks to the 24 tooth (or 58 tooth of the Gen IV LS)reluctor wheel. This book I read said the LS1 from 1997 ECU had as much memory as a desktop PC of the era. LOL.

There's a reason why those engines get swapped in just about anything. They are compact, powerful, reliable, and very economical.

 

[letitsnow]

We all have had different experiences.

I have had many of each sbc and ls powered trucks over the years. Have had many, many more issues with the LS powered trucks.

I now use a 5.7 vortec to pull a medium sized camper to races. Mine is tuned with headers and a decent exhaust. I don't think that I have ever been passed by a 6.0 LS powered truck that was pulling a camper. I have passed many though.

 

[PlayingWithTBI]

OP, what year truck are we talking about? Is it a 88-95 TBI, or a 96-98 Vortec. Swapping an LS into a TBI truck is a little more involved since you're also switching from OBDI to OBDII but, it's doable.

 

[Brothajack93]

Yeah, don't mess around with the 5.0L. Seems they were the worst, underpowered V8, carryover from the 80s when they sucked the power of the V8. 190 HP! As you said, nobody wants them, for good reason.

The 6.0LS/4L80e is probably the best combination out there at a very economical price. At least around here they are around $2200-2500. Seems expensive, but you get a ready to drop-in power train, complete with wiring harness and ECU. If you can figure out the wiring, you won't regret it. 300-325 HP/380 TQ. Not too bad for out of box performance. Mods can you you much higher, but I'm taking stock vs stock, so we'll use that.

When compared to a full rebuild cost of your engine, it makes that $2500 price very affordable, and you step up the the HD transmission. I've got a few 2500 series GMT 800 SUVs LQ4 6.0 (a 2wd and a 4x4) and I'm very pleased with that combination. Both have 4.10 gears. Plenty of power, smooth and very reliable. Really no complaints.

Next option is a 5.3LS. Somewhere around 315 HP/320 TQ. I've got another GMT 800 1500 that I swapped a 5.3 LM7/4L80e from the original 4.3/4L60e. I got to say, the 5.3/4L80e is another great option since you have a 1500. Mine has 3.42. In a lighter truck the 5.3 is just fine with 3.42/3.73. That engine I got for like $450 or so, complete with everything. HP/$ ratio, this probably the best bang for your buck.

Last truck I own is a GMT 400 K3500 with the 5.7/4L80e/4.10. 255 HP/330 TQ. It's plenty torque-y off the line, but just doesn't have the mid to high range power. It's fine, but my experience with the SBC is they can have issues with distributors, missfires, and those spider injectors, especially after the 200K mark...not a fan of that system, but some guys like it. My truck is not a daily, so the SBC is just fine. I only use it like once a month at most. I would pick the 6.0 over the 5.7 if I needed a reliable HD truck though.

At some point I considered swapping a 5.7 Vortec in my 1500. You can get rid of the spider injectors, but requires a "Marine" intake. When I looked, the very few of those intakes that I found were like $600-$800 alone. I said screw that. You can also do a distributor delete on the SBC, but it's a lot of work. Same for the 0411 upgrade. Just do an LS and automatically get all of that, for way cheaper and less headaches.

Note all trucks I mentioned have the 4L80e. It's a great transmission for heavy duty use.

Generally, the LS is just a more advanced engine, there was more engineering and research used on it than the earlier Generation I/II SBC. It has distributor-less ignition (individual coil packs), fuel rail that makes injector diagnosis easier, and the ECU is also much more advanced with ignition timing thanks to the 24 tooth (or 58 tooth of the Gen IV LS)reluctor wheel. This book I read said the LS1 from 1997 ECU had as much memory as a desktop PC of the era. LOL.

There's a reason why those engines get swapped in just about anything. They are compact, powerful, reliable, and very economical.

OP, what year truck are we talking about? Is it a 88-95 TBI, or a 96-98 Vortec. Swapping an LS into a TBI truck is a little more involved since you're also switching from OBDI to OBDII but, it's doable.

It’s a 1997 so a vortec

 

[Spareparts]

My LS experience has been mixed.
Wife drives a 2005 Avalanche with a 5.3L, LS. Other than the early LS piston slap it has ran perfect and still does at 120K.
I had a 2009 Escalade EXT with a 6.2L, L9H. What a POS engine that is. Lost oil pressure. Cam bearings were all but gone. Bought a Reman engine with a 100k/3-year warranty
and had a shop install it to keep the warranty. Loved that truck but never really trusted it
About 8mos later I start it up one morning and i can hear a faint noise. So i check the oil pressure and it was down to 12psi.
When this happened i hated that truck, but i loved that truck at the same time.
I sold the car and gave the guy all the info on where it was installed and all the paperwork. About 4 months later I'm driving by the mechanic shop and there sits the Escalade with the engine out of it.

 

[Erik the Awful]

I don't know how it is there, but here you can get a clean 350 for under $200. Throw $200 into refreshing it and it's a bolt-in solution.

However, if the 305 is running fine, I'd concentrate on everything else before the motor. I can abide a lo-po 305, but I can't abide steering by hope or a busted interior.

 

[stutaeng]

My 6.0 LQ4/4L80 is at 250k. Everything is original and I got it from the PO at 225k. He's a car enthusiast and owned a collection of Corvettes and F bodies with his friend. Really nice guy. He used the truck to tow his cars across the country. I was thinking OP was interested in a Gen III swap, since that's what makes more sense and everyone does.

I see 800/900 2500HD trucks with that engine for sale all the time with 300k, some as much as 400k+, which seems crazy to me, but that's what they have. And those are work trucks, so they get pushed hard and rack up probably millions of miles altogether every year. Same for the 2500/3500 03+ work vans. I'm glad GM leaves the HDs trucks pretty old school.

Even 20 years ago it was kinda of feat for an engine to hit 100k. Now, that's more like 200k or more.

Yeah, the 1500 Gen IV LS engines have that DOD system and those complications and issues. The best you can do is a DOD delete on those. It basically reverts it back to a Gen III.

OP, I hope this is good, honest advice for pros and cons and experiences. I think it's good you have lot's options. Let us know if you have any more questions and good luck with your project.

 

[User_name]

If you want a 350 then go with the 350. But if I were to put the ls based truck engine in it I would go ahead and pony up for a 6.0 and 4l80.