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

[Cole Trickle]

Originally Posted by CC69Rat

Just some numbers to consider:

Daily Driver (using my own)
@ 450miles per week 15mpg I burn 30 gallons. At $5 gl = $150 per week
Same numbers - 25mpg I burn 18 Gallons = $90 week.

I don't drive my trucks every day. Most of us don't if I had to guess.

$240 mo - it would take me about two years to offset the cost of gas @$5000 for my LS swap (done how I would do it). That's a daily driver. No way I drive either one of my trucks 450 miles a week. .. so the time for ROI would be at least 4 years.

$240/mo would pay a monthly payment on a Hyundai, and I get 30+ mpg.

I personally (no disrespect) think the LS swaps are just a craze. The coolness factor, and all the cool kids are doing it. If the 'old school' stuff was going away it would have already gone. Just my opinion. Watch Pass time? How many LS motors do you see. How many big blocks? You want Raw power? How many Top Fuel LS motors have you seen? The Big Blocks still have everything they always had IMO. I'm not about to crush my Big Block just so I can have a 5.3L in my truck. .. just sayin. And it looks like Ole Greenie is still pretty proud of his LS6 @$7500. I would be too.

There's still something to be said about a cleanly detailed carbed motor. I like the LS stuff too, but I just can't justify the cost of the swap or putting an engine in my truck that I haven't gone through myself. I just know more about the old stuff. .. cause I'm old I guess. I have a wife, a mortgage, and a 50hr week job.. My old 350 3OTT will do for now. I can't return $5,000 in the value added to the truck.

If it were a daily I might feel differently but I may put 100 miles a week on my GMC. the rest of the time I ride with my wife, to / from work .. in our Honda CRV.

I'm good with mine as they are for now. $10 a gallon, .. what can we do about it? Crush all the old stuff and sell it for scrap? Why not just buy a new Silverado? Where will they be 43yrs from now? Just my take on it.

I wouldn't say there a craze.....

There the evolution of the SBC. If you think part for part a standard off the shelf sbc will compete with a newer improved more efficent lsx your kidding your self. There are plenty of 5.3 and 6.0 motors out there on the cheap so that what will find its way into our engine bays.

I love the simplicity of my carbed sbc in amy old pick up truck. On the flip side I wouldn't want one in a pro touring big dollar build. I would do a blown ls2/3 or perhaps a LS9 if the budget allowed it in a heart beat.

If your not daily driving it (my sbc with the 4 speed and 3:08 gears actually pulls good mpg) and you have a good running sbc why spend 3-5K for a swap when you can easily get 300 to the wheels with heads and cam for less than $2000.

When the world comes to an end I don't want electronics on my machines...lol

[CC69Rat]

Yall pickin on me? (kidding)

That's why I like this forum. You can express your opinion and still show mutual respect without someone getting their feelings hurt. just discussion..

I have a $5,000 titanium frame road bicycle too and I can justify that all day long ! It's all a matter of opinion so please take what I'm saying as that. Just speaking for myself here, I mean nothing I say as offensive. .. just for the record.

I respect the LS stuff too. I have owned many of them. I am 38yrs old, I have owned 37 cars in my life. I get around a litle bit. Bottom line, I'm not afraid of computers (Im an IT security admin, Telecom guy) I just can't justify the swap for my toys.. and the wife won't let me spend the money.

I have to defend my SBC till the stop selling parts for them. Kitchen remodling, new roof, and International adoption is coming up soon. I gotta make my 408ci BBC, and 350 original matching numbers 0010 block work for now. She doesn't HAVE to give me those,.. but she's cool enough about it to let me play. I have two C10s and appreciate them all. Straight 6, or LS9 it's all the same to me.

[19seventeeCustom]

lsx a craze??? I don't think so. the ls stuff were
using today is the new sbc. it's simple evolution.
just wait until gen 4 stuff becomes more affordable,
500hp with cam only setups, how can anybody that
considers themselves a hot rodder be against that????

lsx- makin sbc/bbc look bad since '97 lmao
Posted via Mobile Device

[BrutonLS1]

Originally Posted by 19seventeeCustom

lsx a craze??? I don't think so. the ls stuff were
using today is the new sbc. it's simple evolution.
just wait until gen 4 stuff becomes more affordable,
500hp with cam only setups, how can anybody that
considers themselves a hot rodder be against that????

lsx- makin sbc/bbc look bad since '97 lmao
Posted via Mobile Device

Well said!! I rebuilt an Ls1 but got in a bind and had to sell it...sad sad day.
but I just swapped my 327/th400 with a 5.3/700r4
The 5.3 is bored to a 5.7 with LS1 crank, cam, pistons,etc. I didn't keep the fuel injection though, I'm going with a 650cfm carb. I put the exhaust on it today, wiring it tomorrow. Here's a pic of the engine before I put it in the truck, When I finish it this next week I'll definitely post up some pics and let y'all know the gas milage, hwy rpm's, etc.

[eagleuh1]

I have a 68 C20 that I rebuilt the stock 327 in it. Just wasn't happy with the milage and performance. I also had a 2005 5.3 in my S10Blazer that I kept cracking the frame at the front suspension mounts. I've worked with both types of engines since I was a teenager. Loved them both. But since I put this 5.3 in my C20, have been very happy with its performance and OK with the milage. Still learning how to use HPTuners to tune myself, hopefully get better milage out of it. Personally I wouldn't go back just beause these engines are so easy to work on and troubleshoot. Especiallly if you have HP Tuners scanner. I've driven mine all over the country towing a travel trailer( 68 28' airstream) and have never had a problem with the engine or tranny. Tows with plenty of power to spare, has never overheated. And runs fine in traffic in the city. I spent more on the 5.3, but probably have saved it back on gas. Just my view. Like the 5.3 better. Good luck however you go though. jim

[eagleuh1]

Oh, they didn't have the 5.3 when I was a teenager, but I worked on Ford 289's and Chevy SBC since a teenager.

[ubtripn]

I am planning on getting the 290 horse GM crate engine when my 350 goes. With the right Rochester and HEI I think I can get it to a point where I don't have to tune it too often. I like the new engines but I got my 68 because of the older technology. I wanted cheap replacement parts as well.

[69GWC]

I have a 06 with a 5.3 and have had many many trucks and the 5.3 is a great motor gets ok mileage but I would rather have a 350 that made good power down low then have to scream the piss out of this 5.3 to get to the power, I feel the power band on the 5.3 is way to high for a truck and even more so if your pulling stuff.
Its funny I shift my 69 around 4000rpms and my 5.3 is just start to find some power at that point..lol

I had a 94 350/700r4 with 3.42s and it did better on fuel and pulled much better then tthis 5.3 with the same gears.
Posted via Mobile Device

[nlped]

Well, I'm going with a 2002 5.3/4L60e swap in my '70 model. The current drivetrain averages about 10-13 mpg's and is a cold natured critter...I love the idea of hopping in, turning the key, and instant response. I've done quite a few FI swaps in other vehicles...never have done this one, but I'll get it all figured out with all the help available on this site.

BTW...the LSX swap I got for $1100 came out of an '02 Suburban with 83k miles on it. Came with motor/trans, complete wiring harness (including the underhood fuse box, battery cables, headlight harness, cruise control module, etc.), the entire system from the motor to the gas tank (gas tank not included) and all the accessories. Heck of a starting point if I do say so myself

[68Stepbed]

I recently finished my LS1 swap in my 68. As for money, I'm way ahead than if I had rebuilt the SBC. Just a simple rebuild with a little massaging to get it with some grunt was going to run me $3000+. I could have also reused my TH350, but how long would it have lasted behind an engine with more power? For $3K, I would have had a 355 making about 250rwhp.

Currently, with the LS1, 700R4, and everything, I'm at around $4K. I still have to build the rearend with 4.11's, so figure another $600-800. My stock LS1 with a cam and valvetrain upgrade is making close to 400 rwhp.

I would have to spend close to $5K just on the engine to get those kind of rwhp numbers from a SBC.

Also, with my old 350/TH350 combo, the best I ever got was 16mpg with 3.73 gears, and 18mpg with 3.07 gears. I haven't currently checked mileage since the rear gears aren't correct, and my speedo isn't hooked up yet, but based on my trip to Chattanooga a few weeks ago, I'm close to the same mpg(3/4 tank each way).

I'm also running a carbed setup, so my numbers may be a tad lower than an EFI setup will make. When I finally get everything tuned out and the correct gearing, I'll start crunching some mpg numbers to see what I'm actually getting.

[69GWC]

$3000 to rebuild a sbc and only make 250hp..? You can buy a crate motor making over 350hp for that.
Posted via Mobile Device

[68Stepbed]

Originally Posted by 69GWC

$3000 to rebuild a sbc and only make 250hp..? You can buy a crate motor making over 350hp for that.
Posted via Mobile Device

Keep in mind I'm talking rear wheel horsepower(rwhp). All crate motors are dynoed using the "gross" method at the flywheel. which means how much power it makes with no accessories. The "net" ratings are what are now used, which determines power with all the accessories installed and working. Then there's rwhp numbers, which always seem way lower than the "gross" ratings due to the power lost in the drivetrain.

For example, the old engine in my truck was a "260 hp" GM 350. If you look it up, it will tell you they got that number using a 4-bbl carb and intake with 1 5/8" headers and the water pump installed, which usually means it's only connected to the crank pulley. It also doesn't specify which carb and intake is used. That engine will typically only make 190 hp with all the accessories on it, then only makes about 135-150 rwhp depending on drivetrain variables.

That means a 350 hp crate engine will only make around 225-240 rwhp.

[Critter]

I have a huge bias in this conversation, but because my name on here is blue and not gold (yet) I will keep my comments to a minimum. I will say that up until a couple years ago, you wouldn't catch me with anything other than a carb under my hood but times they are 'achangin'. I made myself jump into the LS world and I am loving it so far. You can't beat the price vs efficiency vs power aspect of them. To those that weren't impressed with a 5.3 in their ride I can almost promise it was a product of improper tuning. Maybe improper isn't the correct word, I should say, tuning that wasn't matched up to the current vehicle the motor is sitting in.

[el_diablo]

If you guys are swapping in 5.3/4l60s and staying fuel injected, make sure whoever tunes it adjusts the torque management/throttle body response. Stock tune, they are absolute dogs because of that.

Food for thought on tuning- I had an 06 regular cab Chevy with a supercharged 5.3/4l60 and got 21mpg on the power tour in '08.

The built LS7 in my C6Z- I got 30mpg the day I bought it and drove it from Kansas to OKC.

I made multiple trips from OK to California and back with my old 2001 Z28 and always got 25-30mpg depending on how I drove it.

[CC69Rat]

LSX - Makin SBC/BBC look bad since 97.. lmao.

Check my previous post. I have owned an LS motor before, Trans Am and it would run. I give credit where credit is due, but I also recall a 67 Camaro showing me some tail lights one night. LSx is not unbeatable fellers. I didn't poke at anyone, I'm just trying to understand the hype. If they're that powerful, I'll look harder at the swap. Again this is not my daily driver .. so it will take me a LONG time to re-coup the LS swap expense. Do I pull my perfectly good running 350 out of my cruiser to have a good running LS in it, just so I can say I have one? Yall must have more money than I do.

[68Stepbed]

Originally Posted by CC69Rat

I didn't poke at anyone, I'm just trying to understand the hype. If they're that powerful, I'll look harder at the swap.

It's not that they make THAT much more power, it's the WAY they make it. The valve angle allows for a different flow path of air/fuel for better atomization at higher rpms when the air gets turbulent, which makes for more power and better efficiency. This along with the lighter weight rotating assemblies, will allow for power levels to climb well into 6500-7000rpm ranges. Any old small block is pretty much spent by 5500 unless you start throwing alot of go-fast goodies in it. Keep in mind these are the same "type" of go-fast goodies that LSx motors come with in stock form.

The one advantage old sbc/bbc engines have is low end grunt. The 23 deg valve angle allows for better fuel atomization at low rpms, but is limted at higher rpms, which is still much better for a towing application.

Originally Posted by CC69Rat

Do I pull my perfectly good running 350 out of my cruiser to have a good running LS in it, just so I can say I have one?

To that question, I say no. As you stated before, it would a long time to recoup the costs(as far as fuel mileage). If what you have is efficient and works great, and you don't need the extra power, why would you?

Now, if your engine trans combo is getting tired and weak, and it needs replaced anyway, then the answer would be a big YES!! I say that because you can pick up good, used engine/trans combos for what a machine shop will charge you just in labor to build an engine.

Also, if you have a good running setup, but it's not enough, and you want more, then that's another reason to say yes. The reason is it's very hard to make a sbc make good power and still get good efficiency(I'm not saying it can't be done, I'm just stating that it's not an easy task.). The LSx engines are a great combo of power/efficiency.


All that said, the typical costs of swaps that I have seen run anywhere between $3500-$5000+ depending on which engine/trans you get and how many "upgrades" you put into it. As I stated before, it'll cost $3000+ to get a sbc built to make some decent power, then you have accessory drive system, carb, dist, etc. etc. on top of all that. We haven't even discussed getting a trans built yet.

When I did the L6 to V8 swap in 2000, I went with the stock $1500 GM crate engine, but after I bought everything else, and had the trans built, I was over $4000 for the total and still hadn't touched the rearend.

[truckster]

I've never owned an LS, but I've got a 5.7 vortec motor in a 2001 van. I've not been impressed with it, either for power or reliability. In fact, my 97 Ford 5.4 had more power and better mileage in the same size vehicle.

Having said that, my DD Blazer has a stock 350 except for the HEI. I put a Quadrajet back on it (replacing an Edelbrock 1405) and I pump the throttle once and turn the key and it fires right up, whether it's 10 degrees or 110 degrees. I've never had any issues with overheating in traffic. I might be able to get better mileage with injection, but I doubt it would be much more; overdrive would probably make more of a difference.

It's your truck; do what you want with it. But I don't think any motor is a magic bullet to making a brick fly through the air and give incredible mileage.

[69GWC]

Originally Posted by 68Stepbed

It's not that they make THAT much more power, it's the WAY they make it. The valve angle allows for a different flow path of air/fuel for better atomization at higher rpms when the air gets turbulent, which makes for more power and better efficiency. This along with the lighter weight rotating assemblies, will allow for power levels to climb well into 6500-7000rpm ranges. Any old small block is pretty much spent by 5500 unless you start throwing alot of go-fast goodies in it. Keep in mind these are the same "type" of go-fast goodies that LSx motors come with in stock form.

The one advantage old sbc/bbc engines have is low end grunt. The 23 deg valve angle allows for better fuel atomization at low rpms, but is limted at higher rpms, which is still much better for a towing application.

This is what I was talking about on the 5.3s vs the 350, If your pulling something all the time the 5.3 in stock forum does not do it as well as the 350 at all. I am pulling a 5x10 trailer every day and just dont like the fact that the power is all way up in the rpm band and to use it your screaming the motor all the time.
Now If your just wanting fast, hotrod or whatever Iam sure the 5.3 would be the ticket.

{Not directed at anyone just saying}
I still find it hard to believe people getting over 18/19mpg and of these motors, my 06 Z71 with a 5.3 and 3.42 gears has only one time ever even hit the 19mpg range and that was on flat level ground doing 55mph with the wind behind me, truck is pretty much idleing at those speeds.

As of right now pulling my 5x10 trailer every day Iam getting 12mpg and with out it I normally get 14/15mpg.

Iam far from a motor expert just what I have found after driving both motors in similar trucks and gearing for the last few years. I would have had a choice when I bought the 06 I for sure would have bought a 5.7 for how I use it over the 5.3.

['72customdeluxe]

You guys already have your minds made up, but oh well. My '05 lm7 (iron block 5.3) long bed that probably weighs more than stock ran a 14.49 with a breathtakingly slow 60'. 97 mph trap with headers and a tune. Now my pinion angle is about -3* instead of +5*, better tires, better tune, and have traction springs. Hoping for some decent improvement with those changes running it at sea level in cooler air. Gets around 21 on the interstate with 3.73 gears and 30" tires.

[CC69Rat]

Matt- well said man. Its tough to express tone on here. Just know I wasnt trying to be a DB. I just want to know the'why' part. What you said makes sense. The others too.. just trying to learn.
Posted via Mobile Device

[LEEVON]

We went to see a guy this weekend, Dad was looking for a takeout 5.3L and this guy gets them ready, wires, tunes and runs them on a stand. I was telling him about my carbed 5.3L build. I also explained that the reason for the carb is the hot rod theme of the truck, looks and to be different. His exact words were "you ruined it" to which I replied "When was the last time you built a 400hp small block for $500?". Good point, he says. Cheap, clean power no matter how you get the fuel in there!

[CC69Rat]

My GMC sees maybe 1800 RPM if that (right now) Maybe some cones later but .. Definitely not the drag strip. Most of the time it's putting down an old back country road with my arm on the door frame. 3:08 geared, 255hp 350 with a 3OTT and 55mph. I'm getting 20mpg, minimum.

[Jon01]

LS motors make incredible power due to their head design coupled with EFI and modern spark control.
You can make them to everything but sit up and beg with a laptop.
I've had a few LS powered cars(02 SS, 05 GTO, 06 TBSS) and the motors simply never fail to amaze in what they can do.
Ex: I bought my GTO new, by 800 miles it had an MS3 cam, Kooks headers, FAST intake and I'd done a full VE tune.
It put down 456rwhp, got 24-25mpg on the interstate running 75+ with the air cranked and rode like a cadillac. It'd also trap ~94-96mph in the 1/8 mile on 19" tires. Stone stock shortblock and cylinder heads other than valve springs.
Find me an old 350 that will do that with just those mods.

I bought my 5.3 with 80k complete intake to pan with accessories, harness and PCM for $500. $200 4L60E.
I can hack the harness and do the PCM myself with HPTuners.
It'll be getting either a GM hotcam or 228r cam, Circle D converter and a set of headers. I look for it to make around 350 at the tire which would put it well over 400 at the crank.
Were I not doing the cam and other mods I'd have it in and running for about a grand. I'll probably have about 2 in it with the mods though but a stock LS motor is like having a cold beer and not drinking it.

There's no reason it shouldn't get 20+ on the interstate with the converter locked, my wife's Tahoe gets 18-20 going 70-75 after I tuned it and messed with the MAF curve/VE table using HPTuners and my wideband.

Would I pull a good running 350 and replace it with a 5.3?
Yup, that's what I plan on doing this weekend and not doing it just to fit in, doing it for all the reasons stated above.
Anybody want to buy a good running, smoke free 71 350 with all accessories, ram horn manifolds and an Edelbrock intake?

[CC69Rat]

Originally Posted by Jon01

LS motors make incredible power due to their head design coupled with EFI and modern spark control.
You can make them to everything but sit up and beg with a laptop.
I've had a few LS powered cars(02 SS, 05 GTO, 06 TBSS) and the motors simply never fail to amaze in what they can do.
Ex: I bought my GTO new, by 800 miles it had an MS3 cam, Kooks headers, FAST intake and I'd done a full VE tune.
It put down 456rwhp, got 24-25mpg on the interstate running 75+ with the air cranked and rode like a cadillac. It'd also trap ~94-96mph in the 1/8 mile on 19" tires. Stone stock shortblock and cylinder heads other than valve springs.
Find me an old 350 that will do that with just those mods.

I bought my 5.3 with 80k complete intake to pan with accessories, harness and PCM for $500. $200 4L60E.
I can hack the harness and do the PCM myself with HPTuners.
It'll be getting either a GM hotcam or 228r cam, Circle D converter and a set of headers. I look for it to make around 350 at the tire which would put it well over 400 at the crank.
Were I not doing the cam and other mods I'd have it in and running for about a grand. I'll probably have about 2 in it with the mods though but a stock LS motor is like having a cold beer and not drinking it.

There's no reason it shouldn't get 20+ on the interstate with the converter locked, my wife's Tahoe gets 18-20 going 70-75 after I tuned it and messed with the MAF curve/VE table using HPTuners and my wideband.

Would I pull a good running 350 and replace it with a 5.3?
Yup, that's what I plan on doing this weekend and not doing it just to fit in, doing it for all the reasons stated above.
Anybody want to buy a good running, smoke free 71 350 with all accessories, ram horn manifolds and an Edelbrock intake?

[Jon01]

Mature.