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M112 Supercharger Installation (for 99-04 V6 mustangs)

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This post was written by Fink on mustangforums.com.


Eaton M112

Adapter plate(available from mysteed)



90mm Lightning MAF

CAI for a 03/04 Cobra

255 or 310lph fuel


IAT sensor and pigtail

NGK TR6 plugs

Idler pulley and mounting


Serpentine Belt

Gauges (wideband AFR, Boost)

01-04 throttle


RTV gasket maker

Supercharger oil


Socket set and


Wrench set

Tap and die set

Drill and assorted bits



Wire crimper

Extra wire, vaccum hoses, wire loomm etc


nuts, bolts and washers

Part numbers:

Supercharger oil - Xl-4 -


IAT sensor - 9C1Z-12A697-B - Ford

IAT pigtail - 3U2Z-14S411-JZA -


TB gasket - F7LZ-9E936-AA - Ford

Plenum gasket - 9L437 - Ford


gasket - 9H486 - Ford

First off removed the hood:


Proceed to disconnect the negative cable on the battery. Removed air intake

and all connectors, hoses, etc associated with the upper intake.




Now with that completed, you can remove the upper intake.


Put some duct tape over the intake runners or stuff paper towel in them like I

did. Remove the 4 bolts that hold the fuel rail down. Clean the dirt/grime

around the injectors and firmly pull the fuel rail upwards.


Now remove the clips holding the fuel injectors onto the rail. Once that is

complete, you can replace the injectors and reuse the clips.



Put the fuel rail back into its place and push down until all injectors are

seated. Tighten the 4 bolts. Now would be a good time to remove and replace your

spark plugs.

Now you can test fit the adapter plate for clearance. The

only place you will have clearance issues is the front of the fuel rail and the

fuel pressure regulator on the drivers side. You need to put the IAT sensor at

the front of the adapter plate and the rail gets in the way... Nothing a small

prybar and some patience cant fix. Dont forget to put a new gasket under the

adapter plate.



I used a 5/8" tap for the IAT sensor but it was too small. The way I got the

threads in is a little hairy(random pipe reducer).

With all that buttoned

down, you can start on the alignment of the M112. You will need to pry the

coolant crossover/bleeder line to clear the snout of the M112. Just do the same

thing with the fuel rail, pry it little by little.


didnt have my new belt yet so just use to old one and wrap it around the snout

and 2 idlers. You can also see the idler I added. Just a spacer on the back side

and a washer on the front, then I found a bolt long enough to work.



You can do it 1 of 2

ways, the dumb way or the smart way.

I did it the dumb way. I got the

belt alignment completed then grabbed a sharpie marker and marked all the holes

on the adapter plate. Drilled the holes and found out that only the front 2

holes lined up.... *anger face* Well I put the bolts in the front 2 holes and

tightened them, then proceeded to drill each hole again... VERY CAREFULLY since

the fuel rail is right below where your drilling.

The smart way would be

to drill the front 2 holes, tighten the bolts and then drill the rest.


Now you can grab the M112 and apply a bead of RTV along the bottom of case. *I

ran a bead of RTV and the metal gasket for the M112, but you can get away with

just RTV* Place the M112 on the adapter and snug up the nuts/bolts. DONT TIGHTEN

FULLY for at least an hour, let the RTV set up.


While you are waiting for the RTV to set up, take a break or continue on. I

would start with the TB and plenum. *If you are relocating your IAC, do that

before the TB/Plenum* I did not relocate my IAC so I installed it on the plenum.

Put on the CAI and MAF. Hook up/lengthen any connectors that you can at this


I had to lengthen my IAC connector and add some wire to the IAT2

sensor pigtail. The IAT2 sensor gets spliced into the existing IAT sensor

pigtail. If you have a 01-04 the wires for the IAT are with the MAF


Now you can go back and tighten the bolts on the M112. You

should have an engine that looks like this.



Now we can move to the other side. I mounted my coil pack on the case of the

M112, I bought the M112 with the mounting bracket with it so I figured I might

as well use it. Few nuts and bolts and it was mounted. I still need to get some

brake line and make spacers so it sits straight, but it works.


You can mount the boost bypass actuator now. Nothing hard about it, just make

sure the arm is touching the stop. You will also see the block off plate I made

for the IAT sensor hole that the Cobra's use, and the temporary EGR block off

until the one I ordered comes in


Now you can run your vac lines. Here is a diagram:


The line that runs from the plenum to the firewall, is the line that hooks up

directly under the TB on the stock upper. Only 1 nipple on the bypass actuator

needs to have a line ran to it, the other is left uncapped.

There is this

on the passenger side, 2 lines going to a T with a short piece of hose on

it(hooks up behind IAC on stock upper). I just ran a line from the one open end

to the nipple on the CAI



With all the vac lines routed, you can now put on the new serpentine belt. Since

I used the stock crank pulley and stock 3.65 pulley on the M112, I needed a 119"

belt. Add oil to the M112 snout, if you need to. If you havent done so already,

replace your throttle cable(99-00's only). Double, triple, quadruple check


***** I am not including a fuel pump install write up, so you

will have to find one to install the fuel pump **** << *cough* Haynes

manual *cough*

If everything is "flanged up", it would now be a good time

to reconnect the battery and load up your base line tune. Fire it up and see how

she sounds/runs.


Installation time all depends on how fast you want to work. It took me 3 days of

about 8 hrs total work time, mind you, I was working on the rear end as



The T fitting you see in this pic is how I hooked my boost gauge


And I know the coil pack looks out of place, but I was sick of

looking at all these parts, so I threw the M112 on. I was gonna save it for the

4.2 but couldnt resist.

Link to OP: http://mustangforums.com/forum/v6-1994-2004-mustangs/647261-99-04-m112-supercharger-installation.html

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