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How to: LS4 Throttle Body Install

44K views 57 replies 22 participants last post by  goaliemo 
#1 ·
I see this question asked a lot and I will probably be doing this to my car soon. So...

What is it?

77mm bore replacement throttle body for the LSJ. The Stock LSJ throttle body is 68mm bore.

LS4


Stock






How to find one.

GM Part Number: 12568580

or buy one from a junk yard.

COLORADO 04-07 Throttle Valve Assm; (3.5L)
BRAVADA 03-04 Throttle Valve Assm; (4.2L)
CANYON 04-07 Throttle Valve Assm; (3.5L)
ENVOY 03-07 Throttle Valve Assm; (4.2L)
GRAND PRIX 05-06 Throttle Valve Assm; (5.3L)
HUMMER H3 06-08 Throttle Valve Assm; (3.7L)
IMPALA 06-07 Throttle Valve Assm; (5.3L)
ISUZU ASCENDER 03-07 Throttle Valve Assm; (4.2L)
MONTE CARLO 06-07 Throttle Valve Assm; (5.3L)
RAINIER 04-07 Throttle Valve Assm; (4.2L)
SAAB 9-7X 05-07 Throttle Valve Assm; (4.2L)
TRAILBLAZER 03-07 Throttle Valve Assm; (4.2L)

How to Install it.

The throttle blade on the LS4 throttle is wider then the stock throttle body and will not open all the way if installed on the M62. There are two options on how to install it.

1. Buy a Throttle body spacer designed for the LS4 Throttle body.




2. Port the inlet of the blower to widen the opening.

For that, you will need a dremel tool an aluminum cutter and sanding/polishing wheel to smooth things out.

First, dremel off the small lip on the LS4 throttle body on the side that touches the SC.


Disassemble the M62 to separate the housing from the rotors.
http://www.redlineforums.com/forums/ion-redline-discussion/44878-m62-blower-work.html

or stuff a rag into the inlet so no shavings get on the rotors.

Loosely install the TB on to the SC and trace the inside diameter of the throttle body on to the SC inlet to indicate how much material to remove.


Dremel away!

I prefer to separate the M62 housing from the rotors because it allows you to smooth out the entire inlet of the M62.




Then polish everything smooth with a polishing bit. Clean and reassemble the SC. Install the throttle body back onto the SC and the SC back onto the engine.

You will also need a 3.5" to 3" coupler to attach the throttle body to the intake.



Tuning for the LS4.

Change the ETC Area Scaler value from 2950 to 4500. ZZP recommends changing the value to 3688 but there are many values that work.


Lastly, recalibrate your MAF.

If anyone else has anything to add please do so.

:bigthumb:
 
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#7 ·
A Watts 3.5" intake can/should also be used to keep a 3.5" diameter the whole way to the s/c to maximize flow and eliminate restriction. When it's available.
 
#10 ·
so if you buy the spacer no porting is needed?
 
#18 ·
did anyone ever find the complete list of what all vehicles these came on? i'm heading to the junkyard next week to pick up some qc parts thought i might look for one of these while i'm there.
 
#20 ·
anyone know of a quick (but safe) way to connect this to the stock intake?
 
#22 ·
well i guess i'll be figuring out something 2nite lol.
 
#24 ·
yes sir i did. its not beautiful but its fully functional and safe until i decide what intake i'm getting

i used a razor knife to cut the stock elbow off at the first rib (i have 2 of them so i wasn't worried about destroying it). then trimmed the ribs going around so that a clamp would fit in the groove nicely
connecting the reducer to the elbow is a 1.750" long piece of 3" aluminum intake piping that we had here at work.

no, its not the "right" way to do it, but my stock tb was screwed up and i needed to get this on there asap.
 

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#26 ·
power under the curve. it's not just about peak hp

and if you can only find one for 200, then you aren't looking in the right places. i picked up mine for $35 shipped a couple years ago. you can find them on numerous GM vehicles, in scrapyards, etc... for really cheap
 
#28 ·
like tenn said, its the power gained EVERYWHERE
also, the throttle responce makes it "feel" like you gained even more!

i linked here to flit's dyno. the green is with the ls4. hp gained at every single point on the run

 
#30 ·
yeah other than my engine bay neads cleaned something terrible lol. it'll get spruced up before ced at least.
 
#32 ·
yessum.....
 
#34 ·
the only dumb questions are the ones you don't ask, as long as your wanting to learn. ppl will give you a hard time but we're all here to help.

yes the 42's are nearly maxxed out, but IMO you would be perfectly fine adding the ls4. GMRedline will know better than i because i believe he ran that setup in his testing.

the man gains from the ls4 will be when all other mods have been done, as in you engine actually needs more air than what the stock one can provide.

BUT, even when i put the ls4 on my bone stock car, the positive change in throttle response instantly put a huge smile on my face!

if you have one or found a good deal, i sat get it asap!
 
#36 ·
not for quite a while. with a ZZP-style rewire the stock pump will provide for 90% of ppl's goals.

if it happens to go out, upgrade, but if its working just fine then don't worry about it.

have you created an introduction thread yet? if not, do so and list down your mods, plans, goals, etc. Helps us all understand how to help you reach your goals and keeps from whoring up this thread more than necessary lol
 
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