Question for you 5.3L guys

[Vintage Windmills]

I think a coule of you are getting gvwr confused with curb weight on the tahoe. Google lists curb weight maxing out (4x4) as 5050 lbs. and gvwr as 6400. either way thats heavier than any c10.

also the 6.0 trucks generally weigh 1000 lbs more than the 5.3,s so they unfairly get a bad mileage review.

I like the ls based engines but A 97 to 99 350 vortec is a great motor too. Remember that most 5.3s and 6.0s are iron block so the engine weight savings are small.

[scottybaccus]

A fully dressed 350/305 is much heavier than any LS motor. I have the iron head 6.0, and it was sitting 2" higher than the 305 it replaced, even with the forward position I installed in. The aluminum head LS motors save another 80 lbs, and the aluminum block 80 lbs on top of that.

My 2008 Tahoe was 5800 at the curb. My 2009 Silverado Crew Cab, 6100. Both 2wd.
My '87 GMC R1500 was right at 4000 with the 305. Now it should be about 3800.
The best mileage I ever saw in my 2005 Silverado was about 15; in my Tahoe, 19; in my 2009 Silverado, 17. Now 20 in my GMC. The three Chevy's were 5.3/4L60e, 3.73 gears and about 31" tires. The GMC is 6.0 4L80e, 3.08 and 29" tires. They are all bricks. I credit the light weight around town, and the high gear on the road, for the improvement.

[67 cst swb]

Originally Posted by Vintage Windmills

I think a coule of you are getting gvwr confused with curb weight on the tahoe. Google lists curb weight maxing out (4x4) as 5050 lbs. and gvwr as 6400.

You could be correct on me having that confused. I was going out of memory of seeing a weight number on my Tahoe (as in; I saw it somewhere) and I knew my Tahoe was heavy... So 6400 lbs just seemed to make sense.

[VDOG]

This is interesting, I was thinking a 4.8 LS with an intake and carb and a 700r4 to keep the cost down. But after reading this, I might have to do a regular full swap.

[Heavymetl]

LS swap cost with fuel injection, don't forget.

Fuel Cell
Fuel pump
Fittings
Fuel Lines
Wiring
Tune /VATS delete
Electronic trans.

Its not outrageously expensive, but don't be fooled by the $500 junkyard engine price. There peripheral items add up in a hurry. That being said, once you drive a nice LS swap, you'll sell every piece of old small block stuff you own.

[no1udknow]

it really isn't about the weight of the block, the pounds you lose by changing the engine are miniscule. Where you will achieve fuel economy is that the fuel system will adjust the amount of fuel you need according to engine temp, air temp, engine demand, and exhaust efficiency. On top of that, you will likely go with a matching trans (4l80e or tremec t56) which will give you better gear ratios, and then there is the matter of power. People focus too much on hp when they start talking about engines. your peak hp of you engine is usually also near redline, so unless you intend on running your car at redline all the time, or at the rpm's where you achieve peak hp... it's sensless. Low end torque is where it is at. Small displacement engines combined with low end torque is what makes for good fuel milage. If an engine can produce more torque, it dose not have to work as hard to maintain speed, couple that with a set of larger rims/tires, you get a nice flywheel effect that improves gas milage on open roads. Older engines have poor cooling and therefore must utilize looser tolerances and less compression, which is why it takes so much modification to produce fantastic power. The old 350 (late 60's to late 80's) only made between about 175-250 hp with about 250-300 ftlbs of torque with the exception of a few hot spec motors like the ones in vettes and camaro's, most of them were on the low side of that spectrum. Wheras my little 5.3l that is bone stock in my 2001 gmc puts down 320hp and 370 ftlbs of tq, and it is as all hell. Furthermore, with very minimal modification I can see huge gains and maintain much of that reliability.

If I had the money, I would do an ls swap in a heartbeat ( no pun intended ) and the nice thing about doing an ls swap on our old trucks is that they don't need to meet any emissions standards so you can program them to really be efficient.

[scottybaccus]

I have a hot rod fab shop. LS swaps are regular business. No two are alike, mostly because the owners get sidetracked by what they heard or read somewhere. Left up to me, I can make them very cookie cutter, and fix the time, parts and costs.
My personal truck is what I would call a premium, OE type swap. No particular speed parts. No shortcuts to save money at the expense of functionality. Lot's of thought into making sure the parts used are readily available on a road trip, and little custom fabrication, aside from the hard parts that let everything bolt in.
I spent every bit of $6k on parts and materials. I kept the A/C and cruise, ECM controlled electric fans, and replaced everything between the core support and the differential. Drive-ability, reliability and durability were priority over performance upgrades. It can be done cheaper, but not better. It can be done prettier, but not more reliable. It can be done more powerful, but no more durable.
I built my R1500 as a replacement for a 2008 Tahoe LTZ. I miss the leather, but I'm getting better fuel economy, equal reliability and driveability, and will tow equally well with some minor upgrades. I had to go cold turkey, and sold the Tahoe the week I fired up the swap. No regrets. It's been 4 months and nearly 8k miles. It will be paid for in March! If you're mulling it over, be realistic about the costs, and labor involved. I get $4k-$5k in labor for a turn-key install. With that much in parts, you might be wincing, but on a really nice truck, you can double the value.

[TwinsSpeedShop]

5.3/4l60 with tsp 228r cam and 3k stall and I get 16 in town and haven't really checked hwy. 4.10 screw in the back

[Andy4639]

The LS swaps are the common swap now days. The old short blocks have become the old school. Electronic fuel enjection is the new wayand should be here for some time.

I can take my truck into any shop and give them the ECU V/N and they should be able to service it. That being said they should be able to! They would have to be well versed in modified calbrations before i would let them touch it. I can see it in the near future though that any GM dealer will have one tech that is up to date on modified ECU to service stuff. It would be in there favor to get in on this market.
My 6.0 is very dependable as I took it on the 2014 HRPT and drove a little over 3600 miles in 8 days with out any failures. The cold starts alone are well worth the swap money in my opinion.
I bought the scan gauge 2 that is a nice monitor of what is going on with the motor and it has gauges built in to keep a eye on things while driving + you can check codes and clear them as well.

The over all HP and torque can't be matched by the old 350's not for the same money, and the driveablity is way better!

[67ChevyRedneck]

Originally Posted by no1udknow

Wheras my little 5.3l that is bone stock in my 2001 gmc puts down 320hp and 370 ftlbs of tq, and it is as all hell.

Not sure where you got your numbers but a "bone stock" 1999-2002 5.3L truck had 285HP and 325ft-lb stock. I own the same truck (2000).

The 2000-2006 6.0L "only" produced 300HP & 360 Ft-lbs. A couple models did get a HP bump during those times, the SS trucks had 345HP & 380 TQ and the Sierra Denalis had 325/380.

[no1udknow]

Originally Posted by 67ChevyRedneck

Not sure where you got your numbers but a "bone stock" 1999-2002 5.3L truck had 285HP and 325ft-lb stock. I own the same truck (2000).

The 2000-2006 6.0L "only" produced 300HP & 360 Ft-lbs. A couple models did get a HP bump during those times, the SS trucks had 345HP & 380 TQ and the Sierra Denalis had 325/380.

yes your right, I was looking at the wrong engine... my bad hwa hwa

still, the point is it's much better than previous engines with larger displacement. technology has advanced tremendously. It's kind of like when rice burner guys try to tell me that their civic is faster than my truck with it's 350 because they are putting down 280hp out of their little 4-banger, my reply is "yes after you slammed $2000 in to it. If I put $2000 into my engine I could be making 4-500hp and would continue to spank your civic... theres no replacement for displacement"

[Andy4639]

Originally Posted by no1udknow

yes your right, I was looking at the wrong engine... my bad hwa hwa

still, the point is it's much better than previous engines with larger displacement. technology has advanced tremendously. It's kind of like when rice burner guys try to tell me that their civic is faster than my truck with it's 350 because they are putting down 280hp out of their little 4-banger, my reply is "yes after you slammed $2000 in to it. If I put $2000 into my engine I could be making 4-500hp and would continue to spank your civic... theres no replacement for displacement"

Those are fly wheel numbers not rear wheel numbers. LQ4 engines which are the steel block 6.0 numbers and not the 5.3's
The Aluminum 6.0 LQ9 blocks had the 345 Hp.

[Vintage Windmills]

I don't know guys, the late 90's vortec 350's seem almost as good as a 5.3 for less cost and hassle. My opinion is based on having a practical driver with good power, not crazy power. I've owned both for many miles. These 5.3's and 6.0 can have rear main leak at 80k miles, noisy startup, and the broken manifold bolt issue. I think the LS based motors will run strong for 250k+, and the vortec probably isn't quite as good there?

[67ChevyRedneck]

Don't forget the lifter issues... which requires removal of the heads.

[First c10]

I put a 2011 LC9 5.3 all aluminum with the 6L80 trans with stock 3.07gears in my sons truck 315-325hp stock depending which publication you look at. With headers and a tune it gets 20mph easy on the road and about 15 in town. I think that's because it sounds good so my son gets on it a little...... Ok probably a lot!

[Lees68GMC]

Some small differences for small money. The 5.3 with K&N and headers & tune runs great. Mine is 5.3 4L65E, 3:42 gears, 20" Boss 338s Falken Azenis tires. Mileage is great, even though my foots in it all the time. Stock 5.3 with Nothing more than Cam & valve spring change documents 418 HP. My Truck across two different scales is 3680 LBS (without me) Scotty FYI, the LS2 Block is 67 LBS lighter than the Iron block I've weighed both. Each aluminum head weighs 27.5 LBS built.

The bottom line for me is unparalleled V8 performance consistency, with cost efficiency and reliability. Ask yourself, IF Chevy small block V8s of old were so good, WHY would GM spend hundreds of millions of dollars on advanced engine development engineering / designing, ever improving New Generations of better performing, longer lasting, fuel efficient V8 engines?

Just food for thought

[Heavymetl]

Originally Posted by Lees68GMC

The bottom line for me is unparalleled V8 performance consistency, with cost efficiency and reliability. Ask yourself, IF Chevy small block V8s of old were so good, WHY would GM spend hundreds of millions of dollars on advanced engine development engineering / designing, ever improving New Generations of better performing, longer lasting, fuel efficient V8 engines?

Just food for thought

There's nothing "wrong" with the old small blocks.

There's also no comparison to the LS platform. My 347" LS1 dynoed 445 rear wheel horsepower and has ran 11.26@122.8 in my Camaro, all while banging gears. Oh yeah...I've driven it on 2 Power Tours and Hot Rod Drag Week.

Forget about the "350" number as well. A 5.3 with a tune is still a blast to drive!

This is my buddies chevelle, stock LM7/4L60E. Headers, air intake pipe, and a tune. We've got the trans shift issues tuned as well now. It's a riot for an $800 engine/trans junkyard combo. https://www.youtube.com/watch?v=3kRiRzHEriU

Let me put in some sound info. The LS platform was redesigned from the ground up on a fresh sheet of paper. The fuel efficiency comes from the new combustion chamber shape and intake port angles causing a swirl FAR beyond any sbc prior allowing compression ratios to go as far as 11:1 on regular 87 octane fuels if memory serves me correctly the escalade has 11:1 compression and makes over 400 hp STOCK. old sbc ended between 8.?? :1 and 9:1 ? I furget. Tuning a carb and distributer is a joke today. I see LS platforms in my shop regularly with over 300k that run like a top. Will you see 20 mpg in your old barn door in the wind? gl Id have to calc it myself to believe it.I don't get better that 18mpg overall avg with a DURAMAX in my 72 blazer and diesels are way more efficient. The reason a Corvette gets 28 to 30 is pretty friggin obvious to anyone with even a peanut for a brain (its very very aerodynamic) for those w said smaller brain onto other refinements. The ring pack has less tension (= less friction) The roller lifters = less friction, there are many other refinements adding to less friction and reciprocating weight (= mpg) the 5w30 oil = less friction. It goes on and on and on. The turn the key in any weather alone is the key seller for me.