Envoy 4.2 to 5.3 HEADER/EXHAUST

AaronJefferson

Original poster
Member
Feb 18, 2017
14
Georgia
I was just made aware that headers and exhaust may turn Out to a major issue when putting a 5.3 into where a 4.2 was. I have a used 5.3 i pulled Out of a bravada i intend on putting into my envoy but was told that i may have trouble finding headers that will squeeze to fit? Does anyone have any knowledge of this issue? Any Help would be greatly appreciated!

Semper Fidelis,
Aaron Jefferson
 

Tiggerr

Member
Jun 6, 2013
1,324
Perrysburg, OH
The bravada manifolds will work fine... it's the same truck as the envoy....
if anyone makes headers for the 5.3 for this platform they should work fine....

As stated in your other thread about this swap... you're going to need a ton of things from a donor vehicle such as that bravada..
From the wiring harness to the abs unit... trans... crossmember...brake lines...fuel lines.... on and on....
 
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AaronJefferson

Original poster
Member
Feb 18, 2017
14
Georgia
The bravada manifolds will work fine... it's the same truck as the envoy....
if anyone makes headers for the 5.3 for this platform they should work fine....

As stated in your other thread about this swap... you're going to need a ton of things from a donor vehicle such as that bravada..
From the wiring harness to the abs unit... trans... crossmember...brake lines...fuel lines.... on and on....

I spoke with a man who has been doing custom exhaust for quite some time and is the Go yo man for custom exhaust and he Said if i were to get just any headers for the 5.3L they may Not fit due to limited Space... He Said he had Heard of one Guy having to Go directly to hooker and have them design a set specifically for what the fuy had set up... Also is there any way to get around the motor running with o2 sensors... I was trying to get Out of running this set up with cat convertors, just straight back
 

Sparky

Member
Dec 4, 2011
12,927
Front O2 sensors are needed for proper engine function.

Rear O2 sensors are only cat monitoring, you can leave them out. Just would throw a SES light but won't affect the engine otherwise, and you could tune out the rear O2 sensors.

Can use the factory exhaust manifolds on that engine if you want (easiest and cheapest), otherwise you could probably use headers for a Trailblazer SS. They should fit fine.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
There are some headers, no matter which truck (SS, TB, Envoy) don't fit on AWD/4x4 trucks. There are apparently some that do so do your research.

Yeah, you will need everything from the donor. It's not an easy swap.

I didn't know the Bravada ever came with the 5.3 due to its short production run.
 
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Reprise

Lifetime VIP Donor
Supporting Donor
Member
Jul 22, 2015
2,724
There are some headers, no matter which truck (SS, TB, Envoy) don't fit on AWD/4x4 trucks. There are apparently some that do so do your research.

Looks to me like *we're* his 'research' (although he doesn't seem to like the advice we give him) :nono:

I'd be interested to know what the final bill on all of this runs. And labor / hours spent should be part of that total, since they wouldn't exist otherwise. :eyebrowhuh:
 
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