Whats your impression of a 5.3L LS motor in these trucks?

[SweetandLong68]

Hey guys. I was pondering on my new engine/tranny for my truck. This will be my daily driver so I need something will some power but also get decent mileage. My first thought was the 5.3L with 4L60E just because they are plentiful and cheap. But really want a LQ9 6.0L. Just wondering what you guys impressions are with these trucks and the 5.3L, good enough, pleanty of power, mileage? Stuff like that.

BTW this will be going in my 68 SWB C-10. Has a 4.10 gear in it now but I have a set of 3.55s as well.

thanks
CHRIS

[chopnchaneled]

Subcribed

[SweetandLong68]

Here she is! I know everyone loves pics!

This is the BEFORE pic! Getting ready to re-do brakes/suspension/steering/bushing throughout!
Looking at the "Grand Slam" kit, already have the steering rack conversion so that will be going in as well!

[CC69Rat]

I'm curious too. I see the silverados advertised at 12/18 mpg and I have personally owned one (2007 Classic, 5.3 auto with 20's) and it was pretty rough on gas.

How are you guys pulling 'decent' gas mileage out of them? I have a 350 / 3OTT pretty stock with a 1406 Edelbrock, aluminum intake, ramhorns and Flowmaster / 2.25 exhaust and it gets at least 20-22 on the freeway.

My concern is the money it takes to build an older stock 350 or crate motor vs. the LS motor swap and ECM costs of reprogramming, etc. Is it just a cool factor? I'm just not seeing it.

No disrespect, .. please help me understand. If there's something I'm not seeing, please school me. Power is power. It takes gas to make power. 400hp and 25mpg doesn't happen easily regardless. .. LS or an old school v8 ?

Not meaning to open a can here .. just discussion.

[SweetandLong68]

This is a total open discussion for me. Because I have been leaning toward an LQ4 or LQ9 6.0L version. I kinda wrote off the 5.3L pretty early but I wanted to see what other people think that actually have this engine setup and running it. 5.3Ls are plentiful and super cheap. So I am going back and forth... haha

thanks
CHRIS

[BB72CHEVKT]

[QUOTE=CC69Rat;5280021] I have a 350 / 3OTT pretty stock with a 1406 Edelbrock, aluminum intake, ramhorns and Flowmaster / 2.25 exhaust and it gets at least 20-22 on the freeway.

I have never owned a 350 that got close to those numbers.

[PHAT TONY]

Here's the facts I've experienced; 1972 Chev 2wd-350cid/350 trans/3:08 gears all stock-17-19 mpg highway, 1995 GMC 4X4-350cid/4l60 trans/3:73 gears-22-23 mpg, 2003 GMC 4X4-5.3l/4l60e/3:73 gears-16-18mpg, current 1998 GMC 4X4-350/4l60e/3:73 gears-20-22 mpg.
My opinion was the 5.3 was guttless in low rpm's and gas mileage wasn't what I expected.

[gcburdic]

great question and input...keeping them coming!

[Ackattack]

I have a 5.3L in my 68. Compared to the sbc I've had in these trucks (327, carbed 350, tpi 350, tbi 350) there is no doubt that the 5.3L is way better.

My truck has 4.10 gears and the 4L60E and doing 75 I'm getting about 16.5. However, I had a '05 CCSB Z71 with 3.42 gears (and 32" tires) and I would get 20+ mpg out of that in WA where the speed limit was mostly 60.

Also, with the 5.3L, you can bore it out to a 5.7L and use the stock LS1 pistons in it (same stroke as the LS1).

IMO if you don't have an engine or your old sbc engine needs a rebuild, you'll be happier with the 5.3L.

[CC69Rat]

I drive like a papaw, 65 on the freeway. I'm pretty easy on it I guess. But I was shocked too. It is the GMC in my build thread. I promise man, I clocked it. Gallons vs. mileage. I drove the truck 312 miles home, the day I bought it. It came out to 24mpg honestly .. but I'm guessing 20 respectively.

I have also had a hot 350 on a 69 Camaro that no, .. it was more like 8-10mpg cause I drove the pee out of it. I have owned a newer Transam with an LS motor, etc. I have seen both sides and I like them both. I'm considering an LS in a C10 one day too. I like them just as much as the next guy and I have watched some crazy power (LS Fest) out of these motors. Much love for them .. really.. I simply don't know as much about them as I do the old Big Blocks.

I also know there's 14,000btu's of power in one gallon of gas. (12,000 BTUs with Ethanol at 10% mix) .. I'm not talking octane ..

So really? Are you guys seeing 25+ mpg out of hopped up LS motors? I'm asking ... Cause if so, I just might go that route if the old 350 ever lets go.

[Ackattack]

I got 33mpg out of my 99 corvette with 3.42 gears and a 6 speed. But that weighed <3000lbs, had full exhaust and a tune so it doesn't really compare to trucks, but I was pretty happy with a 400HP ride that ran low 12s and respectable mileage.

[CC69Rat]

How much would an LS swap cost vs an older 350 MILD rebuild, 600 holley or something built for mileage and a 700r / 200 swap? Im asking, not being facetious.
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[ctandc]

This is just my opinion, after helping with several LS1 swaps over the years (those tend to cost a bit more than the 4.8/5.3 engines). It all depends on what you have, and what kind of deal you can find.

If you can score a decent 5.3 w/ tranny, wiring harness, PCM etc for less than $3K then I personally think the swap is worth it.

If your are doing this to replace a good running engine, then it's not really cost effective.

You also have to price in whether or not your doing the wire harness yourself or buying a ready made harness. Then programming for your PCM.

If you plan on headers, they seem to get a bit pricey.

My son's truck is low buck for sure. And it will keep the 6 cylinder for now, but I'm keeping my eye open for a deal on a 305/350 TPI setup. I'm rather familiar with them, complete systems can be had for cheap, you can adapt a TBI truck / car wiring harness.

[502ms]

Subscribed. I've been debating this myself
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[Vintage Windmills]

Keep in mind when looking at mileage that most of the trucks today that the 5.3's push around are much heavier than a 67-67 swb 2x4. You'll see good performance and mileage in the older truck that weighs what, 3500lbs? Compare that to the typical 99 to 07 classic ECSB 5.3 4x4 that is 5000lbs. Phat tony points out that the late 90's vortech's are betterr in efficiency. My experience is that they are very similar to the 5.3. The thing about the LSX's is that you can add a cam and tune and make 400hp pretty easily. They are good motors and seem to last longer before rebuilds. The stock tunes are pretty crappy but a 200 dollar tune goes way further than 200 spent on an older 350. I am building my original 350 with roller cam and Vortech heads to keep my truck numbers matching and I am aware that I am spending more money and getting similar performance to if I just swapped in a stock LSx, however it will be a bit of a sleeper, its a tad more interesting IMO, and there is something appealing about not having all the wiring and computer.

[ctandc]

I wondered how the weight stacked up on the new trucks versus the old. I had a '03 GMC Z71 with the 5.3 and it wasn't horrible on gas.

To me it's all about the initial investment + investment needed to get it up and running.

But I'm cheap.

[CC69Rat]

Where are you finding these cheap (low priced) LS motors? Everything I find is $3k range and it has a boatload of miles on it. Maybe I'm just not looking in the right place.

I have looked .. I like the LS motors and I have the prime candidate for one if the numbers motor ever gives up. but, I'm not about to change a high nickel 0010 block for an LS unless it makes sense.

At 4.50/gl - 20mpg = ~.22 or .23 per mile. 30mph = .15 per mile.

At .07 difference per mile - For every $1000 additional you spend on the swap, it takes you 14,300 miles to offset the difference. Yes, older gen small blocks can be had pretty cheap and parts are plentiful .. but to find an LS2 / T56 swap out of a GTO for $3k (?) Is that possible? I don't know .. For $3,000 I can build a 350 than will hang with it. Just thinking Apples to Apples. (Cost wise)

In no way stirring the pot one way or the other, cause I like both ! I'm just trying to think out loud and help justify the cost, all things considered.

That would be a cool show actually. Take an equally prepared C10 body, and a $5,000 budget. One with LS, one with First Gen stuff. See who wins, kinda like that Supercar show with Tanner Felts. Slalom, braking, 0-100-0, etc. That would be interesting.

[ls1nova71]

I like the drivability part myself, if it's -20* out or 100*, you just hit the key and it starts. Altitude doesn't affect it, and I've never had anything close to an overheating problem even wirh the A/C on idling.

My truck in my avatar is bone stock,'71 swb 350/350 3:07 gear with a rebuilt quadrajet and my mix of city and hiway driving always gets me 12-13mpg. It will get a swap when I get time!

[CC69Rat]

Maybe swap the rear gear and see if that helps (?) If mine becomes a problem i will be swapping too.
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[68 short step]

5.3 is the way to go......both are stock 5.3s with a 4l60e trans, only thing both have are cold air intakes, and a tune, the blue white one has headers too....plenty of power, and had way better drivability then a 350/350 combo (click on pics to watch video)

[Cole Trickle]

All of the LSX based motors are great.....

Like mentioned if you can find a decent priced 5.3/4l60 I would go that route with very little thought. shoot even a 4.8 would be fun for a daily driver.

You should be able to find a 5.3/tranny and wiring harness/computer for less than 3K

6.0 became more popular/pricey and alot of people use those as replacements for there 5.3 while trying to go faster in there trucks/cars.

In my experience the 4.8,5.3 and 6.0 only differ about 15-20hp each as the cubes increase. Tq is the biggest difference between the 3.

My 03 regular cab 5.3 made 290 to the wheels with exhaust,intake,electric fan and programming. It ran pretty hard for a semi stock truck 14.3 @ 98

If you have a good running SBC I personally think its a waste of $$$ to swap out for a newer motor.If I had to buy a motor I would go with a modern FI set up.

[Vintage Windmills]

Originally Posted by 68 short step

5.3 is the way to go......both are stock 5.3s with a 4l60e trans, only thing both have are cold air intakes, and a tune, the blue white one has headers too....plenty of power, and had way better drivability then a 350/350 combo

Nice! what were the dyno results?

[SweetandLong68]

Originally Posted by Cole Trickle

If you have a good running SBC I personally think its a waste of $$$ to swap out for a newer motor.If I had to buy a motor I would go with a modern FI set up.

I hear what you are saying but I am lookin at the super driveability of the new fuel injected engines. I am seriously gonna be driving mine every day rain or shine hot or cold so I want it to be ready and willing. But I also want to have something that has some power and guts to it too! And I think a LSX engine would fit the ticket perfectly.

I will sell my old school 327 SBC and 3 speed on the tree, driveshaft and whatever else I have to move on the boards to hopefully help someone else out with there more stock type build.

lata
CHRIS

[OldCreek]

Cole's on the money. All three of my trucks needed motors and the LSx's are what I chose. Driveability, reliability, FI, mpg's and coolness were big factors. All three of my engine/tranny combos were had for less than $2k...closer to $1.5k on average.

After you do one...the next ones are easier.

I had a 5.3/4l60e in a '04 Avalanche. It pulled a heavily loaded flatbed with a '51 pickup on it...adequately. Not impressively, but it got the job done. I can't wait to see what it does in the '72 2wd I'm building.

... I hope to turn the '72 into a daily driver and sell my 2003 import.

[SweetandLong68]

Originally Posted by CC69Rat

Where are you finding these cheap (low priced) LS motors? Everything I find is $3k range and it has a boatload of miles on it. Maybe I'm just not looking in the right place.

I have ran across a few of them. I was not ready to buy at the time but I have definitely seen them. Even ran across a LQ4 6.0L / 4L80E with all the wiring harness, pedal assembly and ECM for 1,600! I know multiple friends of mine that have more than one of these LSX engines and they dont have much money tied up in any of them for sure! So it can be done.

I wouldn't even look at any of the all aluminum motors like that are in my Pontiac G8 because they sell for around 5,000. I am looking at Iron Block, aluminum head motors with reasonable mileage on them.

lata
CHRIS