4.2L to 5.3L swap

[AaronJefferson]

I just bought a used 5.3L engine that came out of a 2001 suburban and intend to drop it into my 2002 GMC envoy which currently has a 4.2L. This will be my first time doing a motor swap but will have assistance with the install. It has the wiring harness but no CPU... I heard I can "flash" the one that I currently have... I'm not familiar with the electronic sector of newer gen motors... Will I need to change motor mounts? Trans bell housing or adapter? Oil pan? What other components will I need to obtain in order to complete this? Any assistance or guidance y'all can give would be greatly appreciated!

Semper Fidelis,
Aaron Jefferson

 

[AWD V8]

A couple of members are/have done V8 swaps but I've not read a finished swap.

Yes you will for sure need mounts. I'm not sure about the PCM or if the engine will work with the 4.2 transmission.

Your best bet would be a transmission from another Envoy or Trailblazer with a V8.

The rear end is different in the V8 trucks, beefier. I don't know how much abuse the 4.2 rear end will take.

A donor V8 truck will provide mounts, PCM, harness, transmission, rear end and any other pipes, hoses, brackets etc.

 

[Tiggerr]

That's going to be a huge undertaking! Especially since you've never done it.

Not sure if you can reflash PCM for the other motor.
You WILL need new mounts, transmission, radiator

All hoses and AC lines, as well as PS lines. If you don't have all front accessory drive items like PS pump, Alternator, AC compressor and all related brackets you'll need that...

you'll need transmission crossmember, I think the driveshaft may be different too.

The ABS motor/pump is in a different location on V8 trucks so you'll need the right lines and have to relocate

fuel lines too, maybe fuel pump as well.....

Complete exhaust, including converters, probably including the manifolds

Idk that the harness from the suburban will do you any good either. Need a v8 harness from a GMT360...

The rear axle is also heavier in V8 trucks

It's a huge job friend....
Can be done...idk if it's worth it though...
May as well go all out and do a 6.0 for all the work involved..

 

[northcreek]

Aaron, I'm all for dropping a V8 in anything. Having said that, this is not an 8 for 6 swap in a 67 Camaro, aside from the electronic issues there is a lot of 5.3 specific stuff that you will need and by the time you are done you will have something that you could have bought off the lot for a lot less. Personally I wouldn't do this without first having a V8 donor truck.
I know that you didn't ask for opinions but, I thought that you might not know what you are in for.
If money/time is no object there are some very knowledgable members here to help you out...Mike.

 

[gmcman]

Reading about other members' experience with the 5.3, it's not a substantial upgrade to the 4.2 in terms of performance.

Low end grunt is more, tows a little better, but IMO if you were going to take on a V8 swap, I would go for a motor that has alot more to offer.

Along the 2002 uses a different PCM so compatibility could be more of a nightmare.

 

[AaronJefferson]

So we have the motor trying to look into it... Does drive train need to be altered in any way?

 

[mrrsm]

Aaron…

Although this tome covers the 4.2L to 6.0L Swap as per @Decembersend … there is much worth reading at the link below to better inform you about how much work is actually involved with your project:

http://gmtnation.com/forums/threads/dead-4-2-swap-to-6-0.12516/

Semper Paratus

 

[Reprise]

So we have the motor trying to look into it... Does drive train need to be altered in any way?

Did you not read the responses you received?
It would be prudent to find a new rear axle (and if your truck has 4wd, to match the ratio of the front diff).
The transmissions are the same, but you might need a different bellhousing. Depending on the year of the PCM, you might need a separate TCM (before 2005, the trans was controlled by the PCM)

You'll need some exhaust mods as well. From what I know, no one makes a bolt-on system, so forget about off-the shelf duals, cat-back, etc.

As the others have said...since the platforms were made w/ optional 5.3, you'd be better off to find one. In the end, it will be a lot less $, time, and aggravation.

 

[Tiggerr]

So we have the motor trying to look into it... Does drive train need to be altered in any way?

At the very least you need a trans, don't think the BH is swappable.. crossmember, relocate the ABS, rear axle should be swapped, re-read my earlier post about all that..

It's a huge undertaking at best..this isn't like swapping out a I6 for a V8 on an old ford pickup or something... this'll be a major PITA... especially since you said you had little experience at this kind of thing..

Get a beat up/wrecked doner truck if you're going to attempt it..unless you have DEEP pockets...

 

[Mooseman]

You practically need a complete V8 GMT360 to swap everything. In fact, there is so much difference that one member swapped the entire body from the I6 to the V8 frame. The only thing you do have some leeway is the choice of block between a truck iron block and the GMT360 aluminum block.

This is a good thread with lots of details. Definitely not for the faint of heart.
http://gmtnation.com/forums/threads...wap-on-2002-bravada-any-input-welcomed.10418/

However, I disagree with the power difference between the I6 and V8. I found my 02 EXT I6 to be a bit of a dog compared to the 06 9-7x with the 5.3. But this could be attributed to both weight and that the TB was geared 3.42 whereas the 9-7x is 3.73.

 

[gmcman]

Gearing as a big part, a 4:10 would be a big difference to a 3:42, small MPG hit but peppier around town.

When I was looking at reman transmissions from GM, my buddy showed me the screen where the 2002 had a different part number to the 2003+, likely because of the PCM.

AJ...I don't know about the PCM compatibility, but the 2002 is different than the later years. I would also check into how the PCM ties into the BCM and whether or not the BCM is isolated or tied into each other....your BCM may not be compatible with a V8 2002+ PCM....that part is above my paygrade.....

I love my 2002, but if I were going to take on a big $$$/labor intensive V8 swap, it would be a 6.0 or sell mine and buy a V8.

I commend your commitment to this project, and we'll help in anyway....just giving you the pros and cons.

 

[Mooseman]

Just having driven my "new" '07 TB LS with 3.42 gears and I6, it's actually close to the Saab's V8 5.3 with 3.73 gears but you can definitely feel the difference when passing. I think my '02 was in bad shape engine wise and the weight didn't help being an EXT. No hard numbers yet but MPG is definitely better.