1998 5.0 Vortec swap to 1999 LS 4.8 vortec

[L31MaxExpress]

There is a reason my 2003 Tahoe I had was a factory 5.7L/5spd version. I drove my sisters identical 5.3/4L60E version and was not a fan. All revs and no real power. When I stumbled across that 5.7L powered unit especially with the 5spd cheap because of some minor issues I jumped on it at the time. The 2004 4.8L regular cab I tuned could not pull its way out of a wet paper bag on the stock tune and tuning it barely made a difference power wise (it was too lean and had too much timing with the intake, headers and exhaust on it) but did improve the transmission shifting. The stock cargo van I rented to move with 15 years ago, had a 4.8L/4L80E and 4.10s. It could not pull the empty van uphill at 70 mph with the cruise set, it would immediately downshift to 3rd, slow to 65 and hit 2nd. Got old in only a 250 mile trip. Once I loaded it up, it got even worse. I would put it on the floor when I saw a decent hill, it would rap up to 80-85 in 3rd then lose speed at WOT and downshift to 2nd and slow to 60.

 

[0xDEADBEEF]

There is a reason my 2003 Tahoe I had was a factory 5.7L/5spd version. I drove my sisters identical 5.3/4L60E version and was not a fan. All revs and no real power. When I stumbled across that 5.7L powered unit especially with the 5spd cheap because of some minor issues I jumped on it at the time. The 2004 4.8L regular cab I tuned could not pull its way out of a wet paper bag on the stock tune and tuning it barely made a difference power wise (it was too lean and had too much timing with the intake, headers and exhaust on it) but did improve the transmission shifting. The stock cargo van I rented to move with 15 years ago, had a 4.8L/4L80E and 4.10s. It could not pull the empty van uphill at 70 mph with the cruise set, it would immediately downshift to 3rd, slow to 65 and hit 2nd. Got old in only a 250 mile trip. Once I loaded it up, it got even worse. I would put it on the floor when I saw a decent hill, it would rap up to 80-85 in 3rd then lose speed at WOT and downshift to 2nd and slow to 60.

My grandparents used to have a Mouflon (sheep) ranch (only 20 acres) in the TX hill country and I was involved with hauling trailers full of them to auction for probably 15 years, starting with a squarebody (305) up to the GMT800. You'd be surprised how many of them you can produce in a year on only 20 acres.

They all sucked about the same pulling up the hills, there's one ginormous hill that twisted around and you'd be lucky to be doing 35 at the top of it because you couldn't carry any speed without jostling the cargo unduly.

Funny enough, when we bought my sons truck and trailered it home in my 2500 Ram (Cummins) we went through there and even with only ~7500 lbs (50% of max) and 800 ft-lbs of torque it was slowing down and had to downsift (probably 3rd, I don't know), boost gauge maxed.

 

[L31MaxExpress]

My grandparents used to have a Mouflon (sheep) ranch (only 20 acres) in the TX hill country and I was involved with hauling trailers full of them to auction for probably 15 years, starting with a squarebody (305) up to the GMT800. You'd be surprised how many of them you can produce in a year on only 20 acres.

They all sucked about the same pulling up the hills, there's one ginormous hill that twisted around and you'd be lucky to be doing 35 at the top of it because you couldn't carry any speed without jostling the cargo unduly.

Funny enough, when we bought my sons truck and trailered it home in my 2500 Ram (Cummins) we went through there and even with only ~7500 lbs (50% of max) and 800 ft-lbs of torque it was slowing down and had to downsift (probably 3rd, I don't know), boost gauge maxed.

If you think towing with a square body 305 that made a fairly flat torque curve with its peak torque at 2,000 rpm was bad, try it with a 4.8L that barely makes more torque at its 4,000 rpm peak. The 4.8L would be wound up in 1st to the moon to get to its ~275 ft/lbs.

 

[0xDEADBEEF]

If you think towing with a square body 305 that made a fairly flat torque curve with its peak torque at 2,000 rpm was bad, try it with a 4.8L that barely makes more torque at its 4,000 rpm peak. The 4.8L would be wound up in 1st to the moon to get to its ~275 ft/lbs.

I've done it with a 5.3 and it towed better overall. None of them were at 2000 rpm going up though.

I loved that square body. It was supposed to be my truck after HS graduation, but a drunk driver hit my grandfather (he was fine) just a couple months before and I ended up with an S10 instead. Major let down.

 

[KansasOBS]

FWIW, Holdener tossed a dual plane and carb onto an LS, and picked up more power down low, compared to the truck intake. Little more like what a TBI would be. Small valve heads on a 6.0 would help also, compared to the stock on an LQ4 (317's), for example.

4.8 is getting on the small side, a 6.0 is only 366 cubes.

I grew up on small blocks, and later big blocks. Once said "screw that LS junk, I'll run this old stuff till I die"...Then I find myself putting a 6.0 in a truck.

You couldn't give me a small block anymore. For the power to money, they just aren't worth it in my opinion. Better block design of the LS leads to longer bearing life. Factory aluminum heads. Better rockers. Roller valvetrain vs non, if older block. Sure there are some guys "Ive got 500k on my vortec", but Ive tore down enough of them in my life, they usually dont look that great on the inside. Bearing wear, rocker wear. Tear open an LS with 300k, and the mains and rods usually look about new.

That being said, I'm not an LS fan. I don't like their cracked rods, the cam bearings are super trash, and I don't like the added electronics on my engine. Would have put in an old 6bt Cummins, but didnt want 1,100lbs hanging on the front end. Thinking about swapping later to an aluminum 6.2.

 

[Erik the Awful]

It's not for our trucks, but do the math on a 4.8 crank in a 6.0/6.2. Forged rods with that crank and lightweight pistons and pins can take 8000 rpm with a good safety margin.

 

[L31MaxExpress]

FWIW, Holdener tossed a dual plane and carb onto an LS, and picked up more power down low, compared to the truck intake. Little more like what a TBI would be. Small valve heads on a 6.0 would help also, compared to the stock on an LQ4 (317's), for example.

4.8 is getting on the small side, a 6.0 is only 366 cubes.

I grew up on small blocks, and later big blocks. Once said "screw that LS junk, I'll run this old stuff till I die"...Then I find myself putting a 6.0 in a truck.

You couldn't give me a small block anymore. For the power to money, they just aren't worth it in my opinion. Better block design of the LS leads to longer bearing life. Factory aluminum heads. Better rockers. Roller valvetrain vs non, if older block. Sure there are some guys "Ive got 500k on my vortec", but Ive tore down enough of them in my life, they usually dont look that great on the inside. Bearing wear, rocker wear. Tear open an LS with 300k, and the mains and rods usually look about new.

That being said, I'm not an LS fan. I don't like their cracked rods, the cam bearings are super trash, and I don't like the added electronics on my engine. Would have put in an old 6bt Cummins, but didnt want 1,100lbs hanging on the front end. Thinking about swapping later to an aluminum 6.2.

I guess I am the opposite. I pulled a 6.0 LS and put a small block back into its place. The LS was a complete and total dog in the application. I have seen rocker wear on stock small blocks, bearing wear on both the SBC and LS are not any different on the newer stuff that has EFI. I have torn down probably 20 of each now. Neglect is what kills both although alot of the Vortrcs issue is from coolant contamination from bad intake gaskets. Carb stuff eats on the bearings. The oil stays cleaner with fewer contaminates on the port injected small blocks and the EFI controller has a better handle on staying out of preignition and detonation conditions. For truck like stuff it is very possible my next swap will be a VK56DE into a GM product if it is not another 8.1L. All of the VK56s are aluminum, the bottom end is more LS like than it is different, they are DOHC and they are a stump puller from the factory. A couple of companies make a bellhousing adapter to put a GM automatic behind them and there are aftermarket ECMs to run them. It is not really any more expensive to cam them than a LS and a factory M45 dual runner length intake manifold adds a good chunk of power and torque as do headers. I have never seen a LS make peak torque under 3,000 rpm but a tuned VK will all day. Give me torque right now vs high rpm horsepower.

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[Sean Buick 76]

They but a 5.3 or 6.0L repond even better to them. NA even a 6.0L is a dog until 3,500 rpm. A LS is like the inverse of a TBI engine. TBI 350 makes all its power right when you hit the throttle. The LS makes its power closer to redline. The old Vortec SBC is somewhere in the middle of those extremes. I tuned on a 4.8L with an intake, headers and exhaust and it made 210 whp and 220 wtq on 87 octane on a safe tune. It did not even crack 200 ft/lbs until it was over 3,000 rpm. By comparison the stock 4.3L Vortec I messed with made 215 wtq @ 2,500 and gained close to 20 ft/lbs from tuning it. The 4.3L only made 180 hp but it had much more low-midrange torque. The stock L30 305 makes a solid 40 ft/lbs at the crank or about 30 wtq more than the 4.3L does.

While I value your input especially the work you’ve done to find power in the TBI and vortec 5.7 engines I do have to disagree in one aspect.

The 4.8 and 5.3 are great engines but you are 100% correct that most modified 5.0 or 5.7 have better torque under 3500 RPM which is where we spend most of our time.

The 6.0 though with long tube headers, and a custom tune is an absolute beast that will outdo even most 454 combos. From idle to 6500 rpm the 6.0 is a monster. Add a cam and another 80-100 hp is attainable.

That being said I’m still building an old school SBC with a single turbo and a blow through carb.

 

[L31MaxExpress]

While I value your input especially the work you’ve done to find power in the TBI and vortec 5.7 engines I do have to disagree in one aspect.

The 4.8 and 5.3 are great engines but you are 100% correct that most modified 5.0 or 5.7 have better torque under 3500 RPM which is where we spend most of our time.

The 6.0 though with long tube headers, and a custom tune is an absolute beast that will outdo even most 454 combos. From idle to 6500 rpm the 6.0 is a monster. Add a cam and another 80-100 hp is attainable.

That being said I’m still building an old school SBC with a single turbo and a blow through carb.

6.0L engine is a dog compared to most big blocks. I pulled one out of a G20 van to put a 350 back in its place. The 6.0L was a dog.

My buddies 1997 ECSB needed a converter stalling 4,500 and a 3.90 rear gear with the all mighty 6.0L to break through a weak 2.00s 60' time. My 2012 Titan was cutting that kind of 60' near stock on the 20s.

 

[0xDEADBEEF]

6.0L engine is a dog compared to most big blocks. I pulled one out of a G20 van to put a 350 back in its place. The 6.0L was a dog.

I'll take any dogs you want to give away.