LS3 Into 2003 Z71 Tahoe
Dec 20, 2019 | 09:10 PM
#1
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LS3 Into 2003 Z71 Tahoe
Need some help here fellas. I just picked up an LS3 with PRC cathedral heads. Going to transplant it into a 2003 Z71 Tahoe. Plan on using my intake. Reading many forums I'm seeing answers and links all over the spectrum. Does anyone know exactly what all is needed to perform this swap?
Thanks in advance.
Thanks in advance.
Dec 20, 2019 | 09:28 PM
#2
This is not an exact list but some of the main points.
The 2003 engine uses knock sensors in the valley cover, the LS3 does not. They are bolted to the side of the engine block. So you gotta figure the wiring out.
The 2003 engine is a 24/1x cam/crank signal the LS3 is a 58/4x, so you will have to either swap reluctor wheels on the crank shaft through a machine shop and install a 1x cam gear or purchase a converter box that is pretty expensive to make it work.
The cam sensor is on the front cover of the LS3 and is on the rear of the engine in the 2003, so again you need to do more wiring.
All your accessories and oil pan/pick up tube will have to be brought over.
You will require larger fuel injectors as your 2003's stock units are too small to even come close to supporting the LS3's power potential. Pray that the weak 4L60e transmission holds together.
The 2003 engine uses knock sensors in the valley cover, the LS3 does not. They are bolted to the side of the engine block. So you gotta figure the wiring out.
The 2003 engine is a 24/1x cam/crank signal the LS3 is a 58/4x, so you will have to either swap reluctor wheels on the crank shaft through a machine shop and install a 1x cam gear or purchase a converter box that is pretty expensive to make it work.
The cam sensor is on the front cover of the LS3 and is on the rear of the engine in the 2003, so again you need to do more wiring.
All your accessories and oil pan/pick up tube will have to be brought over.
You will require larger fuel injectors as your 2003's stock units are too small to even come close to supporting the LS3's power potential. Pray that the weak 4L60e transmission holds together.
Dec 20, 2019 | 10:02 PM
#3
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This is not an exact list but some of the main points.
The 2003 engine uses knock sensors in the valley cover, the LS3 does not. They are bolted to the side of the engine block. So you gotta figure the wiring out.
The 2003 engine uses knock sensors in the valley cover, the LS3 does not. They are bolted to the side of the engine block. So you gotta figure the wiring out.
The 2003 engine is a 24/1x cam/crank signal the LS3 is a 58/4x, so you will have to either swap reluctor wheels on the crank shaft through a machine shop and install a 1x cam gear or purchase a converter box that is pretty expensive to make it work
Going with the Lingenfelter box for this.
The cam sensor is on the front cover of the LS3 and is on the rear of the engine in the 2003, so again you need to do more wiring.
All your accessories and oil pan/pick up tube will have to be brought over.
You will require larger fuel injectors as your 2003's stock units are too small to even come close to supporting the LS3's power potential. Pray that the weak 4L60e transmission holds together.
Dec 20, 2019 | 11:58 PM
#4
The LS3 timing cover should work just fine.
I can tell you right off the bat that if you have a stock truck running 25lb/hr injectors, they are barely even big enough for a 6.0 with bolt on and that's running them at the max. A 6.2 which already makes more power than a bolt 6.0 is going to need way more fuel. Take it from me, you need larger injectors if they are only 25lb/hr.
I can tell you right off the bat that if you have a stock truck running 25lb/hr injectors, they are barely even big enough for a 6.0 with bolt on and that's running them at the max. A 6.2 which already makes more power than a bolt 6.0 is going to need way more fuel. Take it from me, you need larger injectors if they are only 25lb/hr.
Dec 21, 2019 | 01:27 AM
#5
i had to look into all this when i started my 416 build for my c5 z06, there is harness for the cam and knock sensors and your going to need a adapter harness for the throttle body if your truck is DBW (not sure if 03 trucks are?)
id just swap the reluctor wheel instead of using the converter box since the engine is out keep things simple, majority post i seen on the 58 to 24 box have been good but seen a few post that guys did have a problem with them
from what i remember what FFDP was really all that was needed, the block needs the DOD plugged under the valley cover you can either tap the 8 holes with 1/8 NPT and plug them or use the valley cover with the O rings id rather tap them though
my build been parked for a few years now i cant think of anything else at the moment
id just swap the reluctor wheel instead of using the converter box since the engine is out keep things simple, majority post i seen on the 58 to 24 box have been good but seen a few post that guys did have a problem with them
from what i remember what FFDP was really all that was needed, the block needs the DOD plugged under the valley cover you can either tap the 8 holes with 1/8 NPT and plug them or use the valley cover with the O rings id rather tap them though
my build been parked for a few years now i cant think of anything else at the moment
Dec 21, 2019 | 06:23 AM
#6
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i had to look into all this when i started my 416 build for my c5 z06, there is harness for the cam and knock sensors and your going to need a adapter harness for the throttle body if your truck is DBW (not sure if 03 trucks are?)
id just swap the reluctor wheel instead of using the converter box since the engine is out keep things simple, majority post i seen on the 58 to 24 box have been good but seen a few post that guys did have a problem with them
from what i remember what FFDP was really all that was needed, the block needs the DOD plugged under the valley cover you can either tap the 8 holes with 1/8 NPT and plug them or use the valley cover with the O rings id rather tap them though
my build been parked for a few years now i cant think of anything else at the moment
Please keep the suggestions coming guys. Will the LS3 balancer line up with my 5.3 brackets?
If there is a one stop shop online for this info and parts please post it up.
Dec 21, 2019 | 07:55 AM
#7
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From: Somewhere north of 285, south of 985.
Your best bet would be to source a NNBS intake with rectangle ports.
You'll need an xlink as well.
You'll need to figure out the fuel but it’ll come with 36lb or 50lb injectors.
Your 5.3 intake will work with adapter plates but doesn’t flow all that well for an ls3 based engine.
You'll need an xlink as well.
You'll need to figure out the fuel but it’ll come with 36lb or 50lb injectors.
Your 5.3 intake will work with adapter plates but doesn’t flow all that well for an ls3 based engine.
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Dec 21, 2019 | 07:58 AM
#8
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Your best bet would be to source a NNBS intake with rectangle ports.
You'll need an xlink as well.
You'll need to figure out the fuel but it’ll come with 36lb or 50lb injectors.
Your 5.3 intake will work with adapter plates but doesn’t flow all that well for an ls3 based engine.
You'll need an xlink as well.
You'll need to figure out the fuel but it’ll come with 36lb or 50lb injectors.
Your 5.3 intake will work with adapter plates but doesn’t flow all that well for an ls3 based engine.