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OBS ROCK
02-09-2011, 01:03 AM
I was wondering which engine is better for towing? The 5.7 vortec or the 5.3? I tow off and on and would like to know which is better?

FastOrange
02-09-2011, 01:07 AM
5.7L, more torque.

OBS ROCK
02-09-2011, 01:15 AM
5.7L, more torque.


How bout the 6L vs 7.4L

Butch
02-09-2011, 01:17 AM
Stock - Stock
5.7L Vortec
255HP/330

5.3L Vortec
285HP/325

The peak numbers are basically the same but the LS has a flatter torque curve and you can add power easier, a tune alone really wakes them up. Once you swap to an LSX, you have a whole family of interchangeable parts and would be a direct swap if you upgraded to 6.0 later. The older SBC is a great motor but limited in stock form, they also can make awesome numbers but still wouldn't hold a candle to a LS with equal about of money invested. I plan to swap to a 5.3 or 6.0, its gonna be a bitch to get done but after seeing what these motors can do it'll be worth it when I'm done.

Edit: A friends 4.8L equipped NNBS in stock form felt to have as much power as I did in my 13 year old 5.7L, we both have 3.73s.

FastOrange
02-09-2011, 01:18 AM
How bout the 6L vs 7.4L

which 7.4L?

OBS ROCK
02-09-2011, 01:35 AM
which 7.4L?

The 454?

FastOrange
02-09-2011, 01:35 AM
The 454?

What year? like Vortec? TBI? Carb?

OBS ROCK
02-09-2011, 01:39 AM
What year? like Vortec? TBI? Carb?

Oh haha the vortec

FastOrange
02-09-2011, 01:42 AM
well, thats a hard comparison, 454 is a Big Block, and the 6.0L is a Small Block, I would prefer the 454 myself, but ive always been into BBC's.

OBS ROCK
02-09-2011, 01:44 AM
well, thats a hard comparison, 454 is a Big Block, and the 6.0L is a Small Block, I would prefer the 454 myself, but ive always been into BBC's.

Ok, thanks man

DRAGGIN95
02-09-2011, 02:16 AM
Man I like both, but Iam becoming more LS biased, for instance we have two burb's, one a 99 2wd. with vortec 350 with 12,000 miles on new motor it also has a hypercrap, electic fans, injector mod,cai, etc, and it has 3.73's with stock size tires, The second burb is a bone stock 02 2wd with a 5.3 but it was 300 hp stock for that year it also has 3.73's and stock size tires. They are both big and heavy, but with that said, the 02 in stock tune will run off and leave the 99 any time any place, rev's better, pull's harder, just does everything better, it also get's better gas mileage. Now I don't like the nbs but I sure as hell like their engine's, and someday when I have to replace the 350 in the 99 I will drop it in a lake as a boat anchor and put a 5.3 in it's place. Anyway that's just my 2 cent's.

DRAGGIN95
02-09-2011, 02:42 AM
I should also add that I think a 350 has it's place, and is a good motor, but I really dislike a vortec 350, mainly because of the style of fuel injection, and the intake manifold.

OBS ROCK
02-09-2011, 02:45 AM
I should also add that I think a 350 has it's place, and is a good motor, but I really dislike a vortec 350, mainly because of the style of fuel injection, and the intake manifold.

Thanks man, I dont know what ill do yet:)

dropped93
02-09-2011, 11:06 AM
from personal experience, 04 z71 with the 5.3, i tow with it alot through the mountains and even around town alot. not a bad motor, but the transmission seems to be the weak link in it.

Fobroader
02-09-2011, 11:12 AM
If I was gonna swap to a newer engine, 6L all the way. Id love to have that kind of passing power in the mountains. The 350 TBI is a great engine, Ive got over 350,000Kms on it and it runs amazing, doesnt burn oil and the ol' girl will still pick up her skirts and go when you floor it.....but I couldnt imagine what a 6L would be like. Im thinking from a towing point of view but the fact the 6L has so many go fast parts and interchangable parts, it seems like the engine to get.

Sully
02-09-2011, 11:58 AM
vortec 6 is hard to beat.... esp after some work.

Butch
02-09-2011, 12:12 PM
vortec 6 is hard to beat.... esp after some work.

:word: Pretty easy to pull 400/450 off of them.

OBS ROCK
02-09-2011, 01:59 PM
Yeah. ive heard some good things about the 5.3 motors.

OBS ROCK
02-09-2011, 02:01 PM
If I was gonna swap to a newer engine, 6L all the way. Id love to have that kind of passing power in the mountains. The 350 TBI is a great engine, Ive got over 350,000Kms on it and it runs amazing, doesnt burn oil and the ol' girl will still pick up her skirts and go when you floor it.....but I couldnt imagine what a 6L would be like. Im thinking from a towing point of view but the fact the 6L has so many go fast parts and interchangable parts, it seems like the engine to get.

Yeah 6L sounds like a good tow righ.

DRAGGIN95
02-09-2011, 04:08 PM
Yeah 6.0 be would be great, but you asked about 5.3 vs 350, but if you can def. go with 6.0!

OBS ROCK
02-09-2011, 04:17 PM
Yeah 6.0 be would be great, but you asked about 5.3 vs 350, but if you can def. go with 6.0!

Yeah if I find a truck i like with a 6L i will prob buy it. But I still like the obs looks and I havent had any problems with the two obs my family has.

RGV2DRHOE
02-10-2011, 12:01 AM
How bout the ht383e with a mild cam and a marine intake :drool:

DRAGGIN95
02-10-2011, 12:10 AM
Yeah if I find a truck i like with a 6L i will prob buy it. But I still like the obs looks and I havent had any problems with the two obs my family has.

Yeah I like my obs's I have 4 of them, and don't plan to change.

rico47635
02-10-2011, 03:36 AM
Ok fellas. Time to gimme some schooling. Isn't the 6L the 366 engine Chevy has been using in the bigger trucks for a very long time now?

Z Fury
02-10-2011, 09:46 AM
It is. It came out about the same time as the 5.3L V8, as part of the LS engine line.

Sully
02-10-2011, 09:47 AM
and being part of the LS series, it can be made into a friggin monster pretty quick and easy like

SAATR
02-10-2011, 09:50 AM
No, the 6.0L LS series motor and and the 366 big block are worlds apart. The 6.0L (LQ4, LQ9, LS2, et al.) is based on the same architecture as the LS1 that debuted in the Corvette in 96, while the 366 shares its roots with the original 396 that came out with the 65 Corvette. The 366 was a medium to heavy duty truck motor with a small bore and long stroke for low end torque, while the 6.0L motors are larger bore and relatively short stroke, made for torque and horsepower. The 366 is a boatanchor, the 6.0L can be a screamer with minor mods.

FastOrange
02-10-2011, 11:38 AM
Ok fellas. Time to gimme some schooling. Isn't the 6L the 366 engine Chevy has been using in the bigger trucks for a very long time now?

not even close.

FastOrange
02-10-2011, 11:39 AM
No, the 6.0L LS series motor and and the 366 big block are worlds apart. The 6.0L (LQ4, LQ9, LS2, et al.) is based on the same architecture as the LS1 that debuted in the Corvette in 96, while the 366 shares its roots with the original 396 that came out with the 65 Corvette. The 366 was a medium to heavy duty truck motor with a small bore and long stroke for low end torque, while the 6.0L motors are larger bore and relatively short stroke, made for torque and horsepower. The 366 is a boatanchor, the 6.0L can be a screamer with minor mods.

also, the 366 is a Tall Deck Big block, 396 is a Standard deck.

366 is a boat anchor, worst flowing heads ever produced for a BBC, and all it has is torque, not very practical.

SAATR
02-10-2011, 10:54 PM
On a good note, the 366 did come with a forged crank and was the same 3.76" stroke as the 396 and 427, and are/were sought after as a cheap source for a solid bottom end.

rico47635
02-10-2011, 11:55 PM
Good deal. Thanks for the information. I knew that the old 366 was known more for torque than HP. I was thinking maybe Chevy had modified it a bit to fit in their pickups for people who do a lot of towing. So the 6.0 is more for runnin like a raped ape than hookin on to a house and draggin it down the road. I just wonder (I think about stuff like this all the time) how hard it would be to put one of them 6.0s in a mid 80s shortbed.

Butch
02-11-2011, 12:10 AM
In my opinion these LS motors are producing formidable amounts of torque also. Until the LS family came around our go to motor in airboats was a 570lb Lycoming 0540 300hp aircraft motor, these monsters made 750ft. lbs. at 2700 rpms, these are now being replaced with 450lb LS's without old school guys set in there ways batting an eye, to pull 520ft/lbs and 550hp is nothing. Putting one in a square body shouldn't be to much of a project especially compared to our trucks, there's a few current build threads on GMFS with the same setup.

DRAGGIN95
02-11-2011, 01:56 AM
In my opinion these LS motors are producing formidable amounts of torque also. Until the LS family came around our go to motor in airboats was a 570lb Lycoming 0540 300hp aircraft motor, these monsters made 750ft. lbs. at 2700 rpms, these are now being replaced with 450lb LS's without old school guys set in there ways batting an eye, to pull 520ft/lbs and 550hp is nothing. Putting one in a square body shouldn't be to much of a project especially compared to our trucks, there's a few current build threads on GMFS with the same setup.

Word!

Sully
02-11-2011, 09:23 AM
So the 6.0 is more for runnin like a raped ape than hookin on to a house and draggin it down the road.

the nice part of the vortec 6 is it will do both

SAATR
02-11-2011, 05:19 PM
I just wonder (I think about stuff like this all the time) how hard it would be to put one of them 6.0s in a mid 80s shortbed.

I'll let you know in a month or two ;). Got an LQ4 going into an '85, directly.

Hezsus
02-16-2011, 09:14 AM
I asked around about this a little while ago (before i found this forum), mainly about the 6L LS2 engines (out of an 05-06 vette in peticular). I know its not the easiest swap. are the 6.0's in the newer trucks an easier swap? thanks.

chevy_man
03-05-2011, 01:32 PM
I will say that I actually like the vortec better for towing stock vs. stock. It has better low-end power that's more usable. I've towed 10K lbs. a lot with a 6.0L and it takes 4-5K rpm to pull it over any sort of hill. Downshift to 2nd and hold it above 5K rpms at 70mph and it does fine, but it barely pulls 3rd at 3K on a slight slope.

That being said, if you get a cam and re-program either a 5.3 or 6.0 to move the torque down to 2-3K rpms they're an absolute blast to drive. I only have the LQ4 in my denali and stock it picks up and passes well, but about 4K rpms you can feel a surge of power come on with not a whole lot below that.

jdoggystyle
04-17-2011, 05:46 AM
No, the 6.0L LS series motor and and the 366 big block are worlds apart. The 6.0L (LQ4, LQ9, LS2, et al.) is based on the same architecture as the LS1 that debuted in the Corvette in 96, while the 366 shares its roots with the original 396 that came out with the 65 Corvette. The 366 was a medium to heavy duty truck motor with a small bore and long stroke for low end torque, while the 6.0L motors are larger bore and relatively short stroke, made for torque and horsepower. The 366 is a boatanchor, the 6.0L can be a screamer with minor mods.
which 6.0 would be a direct swap from a 5.7 vortec in a 98 k1500

DRAGGIN95
04-21-2011, 02:42 AM
which 6.0 would be a direct swap from a 5.7 vortec in a 98 k1500

Neither, one is a big block and the other is an LS motor.

NacIK
06-26-2011, 01:58 AM
Stock engine I would say the 5.7. I have driven a lot of different combinations, but as far as stock I think the Vortec 5.7 is the best. It may suck in the high end, but it does great for what it was designed for, the low end.

On the other end, a 6.0 with a different cam can be an awesome towing vehicle with some high-end power as well. The only problem is the price factor. 350's are a dime a dozen.

JollyGreen
06-26-2011, 01:02 PM
I sold my 05 Yukon Denali last year because my wife wanted something with a little better mileage. I regretted it when I sold it, wife regrets it now. That thing stock had some balls, and I can imagine with a little work it would flat out scream. Those 6.0's have tons of untapped power. Like NacIK said, only problem is price.

NacIK
06-26-2011, 01:49 PM
Yup. If I became rich somehow you could safely bet on me ripping out my L31 and installing a tuned up 6.0.

SAATR
08-05-2011, 08:22 PM
My 6.0 is an LQ4 out of an 04 2500HD, complete from pan to intake with sensors, harness, and ECM. Cost me 1500 shipped. Would have been 1100 without freight, but I could only find longblocks locally. They are rare in the local wrecking yards, and don't last long when they're there. You don't need to be rich, and could do it easily and fairly cheaply. .

If you bide your time and check out the classifieds on a few LS forums, you could pick up a good cam, lifters, pushrods, and intake on the cheap and have an absolute screamer. Just be prepared to buy some tuning software and a wideband and start climbing up that learning curve.

My own project has been put on hold due to funds availability (read: I'm broke) but will recommence very, VERY soon.

MOBS
08-09-2011, 12:22 PM
Oh this looks like an interesting thread....I see someone asked about a direct bolt-up from a vortec to a 366? Haha....you would need to replace those heads&cam and blow that engine to create ANY power. But, so long as your tranny uses the standard bolt pattern, it would be a "direct bolt up". Ofcourse if you used the later model engines, you would be switching from mpfi to tbi.

Also, in case anyone is curious, the LS 6.0 is a 364ci(same as in GTO's), not 366, and the LS 5.3 is a 323, not 327. I hear alot of salesman telling people that "the 5.3 is an upgraded 327"....I almost want to throw pebbles at them for lyin' like that!!!

SAATR
08-09-2011, 08:24 PM
Also, in case anyone is curious, the LS-6 is a 364ci(same as in GTO's), not 366, and the 5.3 is a 323, not 327. I hear alot of salesman telling people that "the 5.3 is an upgraded 327"....I almost want to throw pebbles at them for lyin' like that!!!

The LS-6, like the LS-1, is 346 cubic inches. ((3.898bore)/2)^2 X pi X 3.62stroke X 8 = 345.7 or approximately 346 cubes. The GTO's came with both the LS-1 (not the LS-6) and the LS-2, which is a 4.00 inch bore. The same math with a 4.00 inch bore (LS-2, LQ4, LQ9) and a 3.62 inch stroke gives 363.9 or approximately 364 cubic inches. While the BBC and the LS motor have a couple of cubic inches displacement difference, they both are still considered to be 6.0L motors, hence the confusion and clarification.

MOBS
08-10-2011, 12:03 AM
I completely botched that, I was using LS-6 to refer to the 6.0 engine, not the actual LS6 engine....sorry for the confusion. I'll edit it in a jiffy.

felon637
08-30-2011, 07:53 PM
My 97 K1500 5.7L 3.73 gears and 285/75/16's has trouble hauling an empty 16ft utility trailer. I run 70mph down the interstate in 3rd gear and it is a freaking dog. Going up a hill is like hitting a wall.

97_chevy
08-30-2011, 09:44 PM
i had i 350 man and just put a 5.3 in my truck and its a big diffrence alot more power with 5.3 man are trucks are real light 5.3s can make alot more power with the right parts i pick a 5.3 hands down

borahshadow
09-01-2011, 05:29 PM
My 97 K1500 5.7L 3.73 gears and 285/75/16's has trouble hauling an empty 16ft utility trailer. I run 70mph down the interstate in 3rd gear and it is a freaking dog. Going up a hill is like hitting a wall.
My truck is identical drivetrain wise. I just got done pulling my 29' camper almost 1000 miles and up and over the continental divide almost 5-6 times throughout the trip. Honestly I was pleasantly surprised how well it did. Sure I wasn't setting any land speed records or anything but on the flat without a head wind I could pull 70-75mph. Going up the hills I had to resort to 2nd gear some times but I have to do that sometimes in the 5.3 suburban with 4.10 gears that I usually pull that trailer with. I stopped at a scale and with a partial tank of water I weighed a little over 12k truck and trailer. I got about 8mpg when I had the trailer in tow which is about what the suburban I mentioned gets with the same trailer. IDK how much more the suburban weighs but it does weigh more so that is part of the reason that it doesn't do too much better than my truck.

I've never driven a 5.3 with the 3.73 before so I can't compare that. These are both stock motors so since the 5.3s are easier to build up that is a major plus for the 5.3. I think a 5.3 wins but stock vs stock if it's geared right I don't think the 5.7 is incapable of pulling a decent load. I still think that the 5.3 is better but it's still no duramax.

On a side note I think I want an 6.0 when my 5.7 expires ( LQ4 or maybe and LQ9 if I want to convert to drive by wire and can find one) That would pull great I think.

felon637
09-02-2011, 07:31 AM
Must be something wrong with mine... I am very disappointed with it.

raymond mckinney
09-02-2011, 11:41 AM
Stock vs stock both my trucks are about equal in towing. But as soon as you do little bolt-ons to the 5.3L the performance jumps leaps over bolt-ons with the 5.7 L31 they just react to every little mod, making it worth the work for the bolt-ons and the money.

NOVAkon
09-02-2011, 12:51 PM
how do the 6.0s work in our trucks, like whats involved in putting one in, i know of course tuning and all that, but do you have to get a pcm from the truck it came from or is there a way to make it work with the existing one, i would loooove to put a 6.0 in my truck, my stepdads trailblazer ss with the ls2 6.0 hauled ass, it was unbelievable how a vehicle that heavy could go so fast, that and a built 4l80e and you could have a serious tow rig and a serious sleeper from a stop light haha

borahshadow
09-02-2011, 06:35 PM
Must be something wrong with mine... I am very disappointed with it.

How many miles do you have? Are you using lots of oil?

MOBS
09-02-2011, 06:52 PM
My 97 K1500 5.7L 3.73 gears and 285/75/16's has trouble hauling an empty 16ft utility trailer. I run 70mph down the interstate in 3rd gear and it is a freaking dog. Going up a hill is like hitting a wall.

Wow, my '95 with 198k hauling a 16" with a jeep loaded did absolutely fine in 4th on highway hills, it actually had no problems at all accelerating from 55-70 in some areas....sounds like you have a major problem somewhere. Hope you find what's wrong.

borahshadow
09-02-2011, 06:56 PM
how do the 6.0s work in our trucks, like whats involved in putting one in, i know of course tuning and all that, but do you have to get a pcm from the truck it came from or is there a way to make it work with the existing one, i would loooove to put a 6.0 in my truck, my stepdads trailblazer ss with the ls2 6.0 hauled ass, it was unbelievable how a vehicle that heavy could go so fast, that and a built 4l80e and you could have a serious tow rig and a serious sleeper from a stop light haha
It's not a simple direct swap but lots of people have put a Gen IV engine in our trucks, including several members on this forum. If you go to the engine performance and maintenance section there is a section LSX swaps where there are a couple of threads about swapping a 5.3 or 6.0 (since it's the same process) in our trucks.

Have you heard of the 411 PCM swap? That's probably the route that I will go if/when I do the swap. Our truck engines can be controlled by the 411 PCM and so can the gen IV engines. That way you can swap to a 411, learn how to tune and stuff and then when you do the swap you only have to do some modifications to the wiring harness and re-tune. Makes it so that you can get some of the work out of the way before actually taking the truck off the road and gives you some practice tuning.
You can also do it by swapping in the computer from the new truck but it can't control everything in our trucks itself so you have to keep the old black box for controlling a couple of things (ABS comes to mind). It seems like more of a hack job way to do it and I'd think that it would make troubleshooting an error code or issue more difficult.


built 4l80e and you could have a serious tow rig and a serious sleeper from a stop light haha
That's exactly what I want... Something that is capable of towing a good load fairly easily and a sweet sleeper...:evillol:

felon637
09-03-2011, 09:17 AM
How many miles do you have? Are you using lots of oil?

Just over 200k miles on it and it might use a half quart of oil between oil changes.


Wow, my '95 with 198k hauling a 16" with a jeep loaded did absolutely fine in 4th on highway hills, it actually had no problems at all accelerating from 55-70 in some areas....sounds like you have a major problem somewhere. Hope you find what's wrong.

I think I just found what's wrong with it http://www.fullsizechevy.com/forum/general-discussion/technical-maintenance/466490-1998-fuel-pump-testing-numbers-before-after-new-pump-installed.html?highlight=fuel+pump

When I put a gauge on my truck the numbers were almost identical to his "before numbers" BUT still within factory specifications. I already did voltage drops on the fuel pump harness to rule out the connector. Looks like the bed is coming off tomorrow.

MOBS
09-04-2011, 03:12 PM
Ah good deal, yeah it needs all the fuel it can get when under any load.

felon637
09-05-2011, 08:54 AM
Ah good deal, yeah it needs all the fuel it can get when under any load.

I had put a "Walbro equivalent" fuel pump from ebay in about 6 months ago for a holding valve problem which fixed that but still ran like a . Well yesterday I put a Delphi unit in and man what a difference. I think I can pull a trailer now. LOL.

It does have a misfire now under load at higher speed and rpm that I didn't notice before I guess because I couldn't put it in that condition with a weak fuel pump. Dizzy gear inspection next.
Thanks for the help.

Chris
09-07-2011, 01:42 PM
Eh, they'll both pull what they were RATED FOR just fine. LS engines were designed to operate most efficiently in a different rev range than the old GenII engines. Just because they need to rev to make peak torque, does not make them inferior to older engines that made peak torque at extremely low revs. I hear that argument a ton. It's a wildly inaccurate myth.

That being said, considering all else (transmission/axle) equal I've had better experiences pulling my car hauler or the family boat with the GenII 5.7L in my rcsb than I've had with an equally equipped 5.3L vehicle. Typically most of my driving (and by default towing) is between central Kentucky and coastal South Carolina, with wildly varying terrain. Anything from 8% grades along I26 and I75 to rolling, two-lane highways more fit for cattle than vehicles. The gearing in a 4L60 seems more suited to the torque curve of the 5.7L, especially when locked in 3rd gear. At 65mph up long mountain grades for example, I can maintain speed and keep the converter locked while in 3rd gear. The 5.3L on the same road would take much more throttle and 2nd gear to maintain speed. Small difference but it's somewhat noticeable. Fuel economy is roughly equal when towing, but my 5.7L will win hands down running with no load. Mainly due to the native lean cruise tables being used in the PCM programming, whereas they're hacked and patched in the LS PCM, so it's not as efficient a system.

scarybowtie
12-02-2011, 12:48 PM
My 95 was a towing.(granted it was not a vortec) after swapping in The 6.0 I could not be happier in any way. I loaded a 00 extended cab dodge half ton on our 20' car hauler and towed 75 mph down the highway in overdrive! With no downshifting. It's worlds difference

Tempted
12-02-2011, 02:36 PM
My 95 was a towing.(granted it was not a vortec) after swapping in The 6.0 I could not be happier in any way. I loaded a 00 extended cab dodge half ton on our 20' car hauler and towed 75 mph down the highway in overdrive! With no downshifting. It's worlds difference

I've had the opposite results. My 99 5.3 Z71(150k) with 3.42s is a compared to my 94 Sierra(300k) 2wd reg/short 5.7 with 3.42s.

scarybowtie
12-02-2011, 03:10 PM
There has to be something wrong man, this wasn't my first tbi 350 truck or my first ls powered truck. The vortec 5.7s are fine (owned one of those as well), but the tbi trucks are just too far behind. A 5.3 even on the pitiful stock tune should have no problem handling a tbi truck.

scarybowtie
12-02-2011, 03:13 PM
how do the 6.0s work in our trucks, like whats involved in putting one in, i know of course tuning and all that, but do you have to get a pcm from the truck it came from or is there a way to make it work with the existing one, i would loooove to put a 6.0 in my truck, my stepdads trailblazer ss with the ls2 6.0 hauled ass, it was unbelievable how a vehicle that heavy could go so fast, that and a built 4l80e and you could have a serious tow rig and a serious sleeper from a stop light haha

http://www.ls1truck.com/forums/showthread.php?t=9535&goto=newpost

ChrisAU
12-02-2011, 03:19 PM
I feel like I'm driving a school bus towing a yacht full of fat people when I get in my 5.7L TBI ECSB after driving my 5.3L Tahoe. And I thought my '92 I had in high school was a fast V-8 truck LOL.

97c1500
12-02-2011, 05:28 PM
My tuned 5.3 in my new truck would walk all over my old tuned 5.7 vortec es the 350 did have more low end grunt but once you get it above 3k it falls on its face compared to the 5.3

Tempted
12-02-2011, 05:39 PM
My tuned 5.3 in my new truck would walk all over my old tuned 5.7 vortec es the 350 did have more low end grunt but once you get it above 3k it falls on its face compared to the 5.3

Yeah my 5.3 has decent power on the big end, but is a dog from a dig with a load. My 5.7 certainly out pulls my 5.3 from a dead stop. Again, my 5.3 is in an extended cab Z71 so it is having to push a little more weight than my 2wd reg/short. I pull heavy, heavy loads on a routine basis and the 94 has been leaps and bounds a better tow rig. I've gone through 3 4L60Es but I have never cracked the motor. Valve covers have never been removed. The 99 Z71 is on its second motor and 2nd trans, and has half as many miles. It also hasn't towed near as much as the 5.7. I'm gonna keep the old TBI 5.7 in it until it pops. I know I can get 500k out of it but it would be cool to have a million mile half ton that has always been a tow truck. When it gives up a Cummins is going back in. Should make for a near perfect tow rig with a Cummins/Allison/14 bolt.

scarybowtie
12-02-2011, 06:03 PM
Most of the lack of low end you notice in the 5.3s is torque management and the factory tune. A good tune from nelson, or equivalent will do wonders for your low end

Tempted
12-02-2011, 10:47 PM
Yeah I have SCT Advantage software, just haven't felt like making a custom tune for it. If anyone has the tables of a good tune I sure would like to see them ;)

jantzer
01-08-2012, 07:59 PM
A 5.3 with any mods at all will walk all over a TBI 5.7 with stock heads on it.

jantzer
01-08-2012, 08:00 PM
The TBI 5.7 with some good aftermarket heads/cam makes good power however. Had a some trickflow heads on one that ran really well.

Hezsus
01-09-2012, 06:46 AM
Our 5.3's get better mileage towing than I do, but if i leave it in 3rd Its pretty easy towing.
we have a 2002 5.7l express van that regularly hauls our 9000lb trailer, and it does better than my 5.7 or any of our 5.3's or 4.8's.

DieselPower
01-09-2012, 11:30 AM
Gearing is everything. A LS motor is designed to provide more power and in stock form has some pretty nice upgrades over a stock 350. Better spark, better flowing heads, better induction system, - it's just a higher performance engine right out of the factory. It is built to handle higher RPM's, giving more high end power and losing some torque on the low end as a result. Going stock on both motors, the LS will want some lower gearing in order to better utilize its power advantage - but given that it should easily outperform a stock SBC. Realistically a TBI engine doesn't perform much better than a mid-70's, detuned, emission-laden SBC. The potential is there though - with a decent cam, stroke it, head upgrades, improved induction and a decent exhaust - you can make a pretty good towing machine out of it. Target low end torque and put in some decent gearing and the LS motors would be hard-pressed to match the towing capability. The SBC makes pretty good low end torque - which really helps in towing anything heavy.

ccreddell
01-09-2012, 11:50 AM
TBI motors have enormous potential. The guy over at TBIchips.com is getting 300+HP and 20+MPG out of them pretty easily.

DieselPower
01-09-2012, 12:53 PM
TBI motors have enormous potential. The guy over at TBIchips.com is getting 300+HP and 20+MPG out of them pretty easily.
Not from a stock tune with all stock parts. Yes, all SBC's have enormous potential. I've pulled 400+ hp and gotten 22 mpg out of one without Nitrous or forced induction - and that's nothing special. "TBI" motors are just low compression SBCs with a mild cam, marginal heads and a cheap fuel injection system - like a detuned 70's vehicle (only they came with a carb on it). Start upgrading those parts and the potential becomes realized.

ccreddell
01-09-2012, 01:03 PM
Nobody was talking about a stock-unless i missed something. Hes putting vortec and roller cam-basically a vortec shortblock-with a TBI and a tune.

DieselPower
01-09-2012, 04:12 PM
Nobody was talking about a stock-unless i missed something. Hes putting vortec and roller cam-basically a vortec shortblock-with a TBI and a tune.
There is some mixing and matching of various SBC models and the overall topic is a comparison of a 5.7 vs a 5.3 LS in towing. A vortec head seems to make the entire motor a vortec motor, but a TBI induction system made the engine a TBI motor (generically, no particular individual references here.)... I was trying to be more specific with what constituted a "TBI" motor so that nobody was missing anything. If you swap out the heads and cam, it's no longer the "wimpy" stock TBI engine. No disagreement on the potential of the SBC on my part - but the components used in the engine dictate what the potential is. The OP's question implies stock motors and some responses do not make that same assumption. Regardless of which motor is in place, I'm just pointing out that gearing is going to matter at least as much as the engine.