4.2 to 5.3 Engine Swap Talk

groundshock

Original poster
Member
Dec 4, 2011
248
I've looked everywhere. You got an absolute steal. Everything I've found is going for 3-5K depending on the damage.
 

Pittdawg

Member
Dec 5, 2011
538
groundshock said:
All fine and dandy, but no doubt you're probably maxed out on the 4.2, or at least getting into diminishing returns. LS based 5.3, well, sky's the limit.

Dollar for dollar, the V8 is the better option. No question.

All depends on what you what. If you want over 400 hp all N/A engine, you have a good point...good luck man I hope you get 'er done!
 

Jkust

Member
Dec 4, 2011
946
bigytwotone said:
You don't need to find a EXT I was able to find a SWB with the 5.3

If it wasn't an EXT it'd have to be a Denali, or one of the few v8 swb tb's...one of the later ones. I suppose you could find a high mile Rainier since they are pretty common back to 2004 with t v8 but it'd be the lower hp v8.
 

northcreek

Member
Jan 15, 2012
3,310
WNY
Pittdawg said:
Don't get me wrong a 5.3 swap would be sweet but there are plenty of mods available for a 4.2. I'll run against any stock 5.3 and whoop it with my modded 4.2.

Maybe but...it will still sound like Grandma's car while doing it:raspberry:
 

navigator

Member
Dec 3, 2011
504
ScarabEpic22 said:
You have to do driveshaft work with both I believe, I know the 9.5" needs a shorter driveshaft but cant remember if the 8.6 does (I think it does)......
Several of the offroad guys have done the 8.6 swap. I'm pretty sure it is a direct swap.
 

Jkust

Member
Dec 4, 2011
946
northcreek said:
Maybe but...it will still sound like Grandma's car while doing it:raspberry:

Plus I don't think it'd woop it so much as keep up with it in some spots and slightly beat it at the margins...thats of couse assuming the 5.3 owner hasn't attempted any mods. There was a thread a while back of someone who had a modded 4.2 and a stock 5.3 with some fun comparisons.
 

BoldAdventure

Member
Jun 28, 2012
1,634
Jkust said:
Plus I don't think it'd woop it so much as keep up with it in some spots and slightly beat it at the margins...thats of couse assuming the 5.3 owner hasn't attempted any mods. There was a thread a while back of someone who had a modded 4.2 and a stock 5.3 with some fun comparisons.

Not everyone interested in this is doing it for driving around racing. I'm interested for off road and towing applications. My wife and I would like to tow an airstream up hill faster than 55mph thru the rockies.

Let's try to keep the thread closer to discussion on technical aspects or we'll end up with a thread like the TrailVoy with 15 pages of guys going back and forth about their opinions. You've given us yours and why people should stick with the I6. We appreciate it. Now lets discuss what needs to be tackled to accomplish the swap.
 

groundshock

Original poster
Member
Dec 4, 2011
248
I agree with Mike. Let's keep this thread on track and free of debates on what we individually think about the swap.

Feel free to start another thread if you want to discuss the pros/cons. Thanks!

So far I've found only one truck that meets the criteria, at least for my own purposes.
 

Jkust

Member
Dec 4, 2011
946
mikekey said:
Not everyone interested in this is doing it for driving around racing. I'm interested for off road and towing applications. My wife and I would like to tow an airstream up hill faster than 55mph thru the rockies.

Let's try to keep the thread closer to discussion on technical aspects or we'll end up with a thread like the TrailVoy with 15 pages of guys going back and forth about their opinions. You've given us yours and why people should stick with the I6. We appreciate it. Now lets discuss what needs to be tackled to accomplish the swap.

Well, I'm responding to the the other post comparing the performance of the two. I just want to see someone do the swap since it is will go down as a legend. We've all piped in on a dozen of these and nobody has actually attempted it.
 

Pittdawg

Member
Dec 5, 2011
538
Jkust said:
Well, I'm responding to the the other post comparing the performance of the two. I just want to see someone do the swap since it is will go down as a legend. We've all piped in on a dozen of these and nobody has actually attempted it.

If you are going through the hassle of the swap, why not go all in for the 6.0 liter :undecided: ?
 

Sparky

Member
Dec 4, 2011
12,927
navigator said:
Several of the offroad guys have done the 8.6 swap. I'm pretty sure it is a direct swap.

It was pointed out to me that technically the drive shaft should be ever so slightly shorter with the 8.6, however as we've seen it is close enough. It pushes the slip yoke in a tad bit farther but it isn't too far (darn close tho).

Now if your slip yoke is rusty like mine was then the non-smooth surface could chew up your output shaft seal. Just be aware of that. Of course, mine also had a siezed U joint so it bashed it to death also.
 

eutechnyx

Member
Mar 31, 2012
375
Ive thought about this swap so many times and like you,have not been able to find any solid information. It would seem like such an easy swap.
 

eutechnyx

Member
Mar 31, 2012
375
C-ya said:
I went the low tech route when I put a carb'ed SBC in my Hombre (aka S-10/Sonoma). Lost anti-lock brakes and factory speedo, but whatever. Were I to do it again, I'd get as much of the harness and controls from a full-size that had a V8 and use a newer engine that was FI. It was out of my budget at the time.

Good luck with the project if you decide to take it on. I think it would do-able since, like was posted earlier, it was a factory option in these vehicles. It's not like you are reinventing the wheel here like I did. The S-trucks had the 4.3 as their biggest engine option.

Not to argue or be a butthole but I would say a v8 swapped s-series is so common and ive done 2-3 of them myself that its nowhere near reinventing lol. There is SO many parts available to make that the easiest and cheapest swap you can possibly do in an s-series. Honestly IMO,this swap is more re invention than a carb'd sbc in an s10 lol.
 

groundshock

Original poster
Member
Dec 4, 2011
248
Dropping a LT1 in a 4.3 S-Series can be as easy as dropping in the engine and plugging in a computer.

It's stone cold stupid easy.
 

MikesTB

Member
Mar 2, 2013
24
I have a 96 Silverado that had the 5.7l vortec in it but I spun all the bearings in the cam and crank beyond repair so I dropped a 1980 carb 5.7l with a 2 speed powerglyde on the back of it. That's the only other engine I had to put in it it was a pretty easy conversion.
 

limequat

Member
Dec 8, 2011
520
MikesTB said:
I have a 96 Silverado that had the 5.7l vortec in it but I spun all the bearings in the cam and crank beyond repair so I dropped a 1980 carb 5.7l with a 2 speed powerglyde on the back of it. That's the only other engine I had to put in it it was a pretty easy conversion.

:confused:
 

C-ya

Member
Aug 24, 2012
1,098
eutechnyx said:
Not to argue or be a butthole but I would say a v8 swapped s-series is so common and ive done 2-3 of them myself that its nowhere near reinventing lol. There is SO many parts available to make that the easiest and cheapest swap you can possibly do in an s-series. Honestly IMO,this swap is more re invention than a carb'd sbc in an s10 lol.

Going from a 2.4L 4 cylinder with a 5-speed to a V8 was a pretty decent endeavor. Had I started with a V6, it would have dramatically easier. Motor mounts, radiator, trans/trans brace. That's why I went low tech instead of trying to rewire the whole truck. Nothing from the 4-banger could have been reused.

Yes, it is a very common swap and I used many of the parts available for it. I went with a serpentine setup to keep a stock look as the 4.3's were serpentine and I wanted A/C in it.

Looking back and looking at the subject of this thread, I probably could have dropped an FI motor in, swapped the ECM and harness and been good to go. I didn't think of it that way. Today, I would. Maybe the time and experience between then and now makes me think what I did was much harder than the subject of this thread. Today, I would think a harness and engine swap should be a cake walk. It may end up in fact NOT being a cake walk, but at the moment, I see it as definitely doable project.
 

gmcman

Member
Dec 12, 2011
4,656
groundshock said:
All fine and dandy, but no doubt you're probably maxed out on the 4.2, or at least getting into diminishing returns. LS based 5.3, well, sky's the limit.

Dollar for dollar, the V8 is the better option. No question.

What are you after with the 5.3...forced induction or normally aspirated?

Reason I ask is before you swap the motors, consider building the 4.2 first. If I were contemplating what you're doing and had some time...I would find an 06 head or newer and have it ported, then have some cams made and this has been documented to provide 50HP alone, and I believe with either none or very mild porting.

Have a custom tune done, remove the torque management, swap an 8.6 rear or an SS rear and hope the tranny holds out....a vette servo would be a must IMO.

The 06+ heads are much beefier in the port areas and can really be hogged out, all that with some headers should really wake it up.

Of course a 5.3 would be sweet but that's a lot of labor saved and $$$.

Just some opinions.
 

Sparky

Member
Dec 4, 2011
12,927
There are a few Transgo kits that range from fairly simple that improve reliability in some key areas all the way up to a full blown shift kit. I'd at least do their SK-4L60E "code buster" kit at a minimum. I went with a little more complete kit put together by an ebay seller with that Transgo kit, new separator plates and seals, Vette servo, and Sonnax pinless accumulators to replace the stock plastic ones. Worth doing to any 4L60E IMO as it doesn't cost all that much and can really take care of some weak points that can lead to transmission failure. 174k on my 02, which the earlier years were considered the weaker years also. My other 4L60E in my Camaro has almost the same mileage and went from slamming 1-2 shifts and torque converter lockup failure to perfect after the install, and that was a long time ago now.
 

v7guy

Member
Dec 4, 2011
298
I asked this question several years ago on trailvoy and got the same responses I did when I was looking to swap from a 3.4 to an LT1 in my Firebird many years ago. I ended up finding a rolled firebird with an LT1/6spd and took most of the wiring, drivetrain etc. Despite what a lot of people told me, it wasn't actually that bad of a swap. Knowing what I know now I could do it in 2 or 3 days.
The biggest thing I hear being a problem with the 360 is the BCM causing problems. I've never been able to get an answer as to why the BCM is going to cause problems though.

The suggestion to find a totaled donor is a valid one. Even if the entire body wiring needs swapped along with the BCM it's not a big deal cause you have it. I know from experience that GM will use the same wiring harnesses, fuel lines, clusters etc if it can just because it can save money doing so.
 

Kelly@PCMofNC

Member
Mar 16, 2013
184
Sounds like a great project - good luck!! We have a lot of people talk to us about swapping in a V8 but very few actually do it. It will be a unique truck for sure, and like you said the possibilities with the 5.3 are endless!
 

northcreek

Member
Jan 15, 2012
3,310
WNY
I've done engine swaps and love the mechanical challenges that pop up. What scares me about your plan is the electronic glitches that will be poping up. There are so many considerations regarding electrical and state inspection/emission stuff that it will turn your hair prematurely gray.
Also for all your work, $$ and :hissyfit: you will have a truck that anybody can buy.
These trucks, even the top models are now within the price range of mere mortals, so why not ditch your beloved truck, buy exactly what you want and trick it out? you will be money and hair ahead....Mike.
 

CoreyH

Member
May 5, 2014
11
Anyone have any luck regarding this thread? I am in the process of building my 5.3 engine now for a swap in my 04 TB i6. My engine is just about done, i have an ECU from an 04 EXT 5.3 model, still looking for an engine harness from an 04 5.3, and the mounts, hopefully within a few weeks ill be able to start yanking the 4.2 out and seeing what all fabrication will need to be done to get this 5.3 shoved in there!
 

CoreyH

Member
May 5, 2014
11
How about we get some feedback from the people that were actually interested in doing swaps....
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Another member was doing a similar swap on his Bravada to a 6.0L. Maybe try an find that thread.
 

CoreyH

Member
May 5, 2014
11
I've seen threads with people who have done it, but they bought a donor SS and literally swapped everything. But I have yet to see a completed non-donor vehicle swap with just the engine. I'll do another search again but if I don't find one, I'll just start another thread with my build.
 
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Jrgunn5150

Member
Dec 18, 2014
68
Ionia Michigan
I've seen threads with people who have done it, but they bought a donor SS and literally swapped everything. But I have yet to see a completed non-donor vehicle swap with just the engine. I'll do another search again but if I don't find one, I'll just start another thread with my build.


If I were doing it, just IMO, I would separate the vehicle and engine harness. A basic E67/T42 combo, that makes tuning easy, you can use any late model LS motor, and if you put your lights and windows on a more normal relay/fuse setup, you won't have to fuse with diagnosing BCM's and LGM's and blah blah
 

ddaddy

Member
Mar 7, 2019
1
Washington
So this an old lost and I want to clear the air on having to fab engine mounts etc. this is a very easy swap if you can find the right donor vehicle. I just did a 5.3 LM4 swap in my 2wd drive trailblazer. My donor rig was a 2003 envoy xl. The chassis are the exact same between these two. The frame engine mounts off the envoy bolt right in to the blazer frame NO NEED TO FAB DIRECT FIT!! I used the radiator from the envoy (same size as the inline 6 just different locations for the hoses) power steering lines from the envoy drop right into the blazer. Your power steering will be on the driver side like the envoy once the 5.3 is in. I used the AC condenser and ac line from the envoy. Had to braze a cap on the line that crossed over to the drivers side for the rear ac. Transmission moved 2-5/8” forward so did some fab on the transmission cross member. Used the bell housing off the 5.3 4l60e and used the torque converter from the 6 cylinder transmission. Higher stall. Driveline from the envoy was the perfect fit into the blazer. Also switched to an electric fan. Fuel lines from the envoy went right in and only needed to switch one fitting underneath the blazer. Fuel pump is the same on the 6 cylinder as the 8.

Wiring!! I have the best harness guy in the world. First and fire most the fuse blocks look the same they are not! He had to re pin 21 wires. Also 37 wires came out of the firewall that had to be spliced into the 5.3 harness. PCM was used from the envoy for the gas pedal. The pedal from the 6 cylinder is the same as the 8. After this the harness is plug and play. This swap is not plug and play without harness work! The blazer fired up and has been running with no codes no issues.
 

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Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
Try sending him a PM. He hasn't been here since March.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
If using iit n a GMT360, yes. The block is basically the exact same except that the truck block is iron and the 360 is aluminum.
 

mrrsm

Lifetime VIP Donor
Supporting Donor
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Oct 22, 2015
7,642
Tampa Bay Area
For anyone interested... eBay has this Offer for converting Your Own Engine Harness over to a STANDALONE - RE-WIRED Complete Engine Harness for $300.00 The work includes using your own PCM to LOAD UP A TUNE for the LS1- LSX Engine Swap:



LSSWAPPCMANDHARNESS.jpg
 
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