M90 root blower how to info


Jan 26, 2008
Just outside Philly PA
Stangnet is primarily a V8 mustang site with the V6 part as sort just there because. Most V8 guys dont think much of the V6s so mod projects on the 6 arent really addressed here. It is true that for every mod done on a six the 8 will make more power and it would as there are 2 more cylinders to work with.
Upside is that V6 stuff can sometimes be had cheap. Also more often than not the V6 guys are not modifiers and thats not a knock against the v6 crowd at all because there are some guys doing bad ass 6s out there.
All that being said
I recently got involved in 3.8 M90 project swap into a mustang. Some of you may think of the roush m90 first but others will remember the t bird supercoupe from 89-95. I researched it first and most of what you would want to know can be found on v6power.net but over the past few days to a week the site has been up and down. Why I dont know but I thought I would try to compile as much of the info as I can into a tech thread for here.
Ive basically copied alot of info verbatim from a few different sources and am pasting it below as it appeared. I'll try to clean it up as I go so that it will read better but take it into consideration.
A guy by the name of V6Sprout put most of the work into this so all credit to him.
Maybe this can get stickied so it doesnt slip away eventually. Just a thought.

---> Roots blower how to
So you want to install a roots blower from the thunderbuird Supercoupe on your mustang eh? Will it work? What all is needed? How hard is it? How well will my mustang block hold up? Read on.........

First of all WILL IT WORK?

YES but its not easy

Second what all is needed?

LOTS! Basically its easier and cheaper to buy the entire SC motor, but if you want to install it on your mustang block here is what you need.

-Roots blower
-SC blower top
-SC lower intake
-SC rear blower intake with SC TB
-Rear intake (from IC to lower intake)
-SC thermostat housing
-SC jackshaft pulley bracket
-SC PS pump bracket
-SC crank pulley
-SC water pump and pulley
-PS pump pulley (you can us your mustang pump)
-SC tensioner pulleys (all 3)
-if using the SC block/crank then use the 94-95 neutral balanced dampener with exeter gear, some dampeners off the F150 will work as well.
-if using the mustang block/crank then use you stock mustang dampener
-if using the SC block/crank then use the SC flywheel/flexplate
-if using the mustang block/crank then use the mustang flywheel/flexplate
-Mustang or SC starter will be fine, they are the same
-Mustang headers
-SC heads are better but Mustang heads would probably be fine (SC heads are supposedly a little stronger)
-SC injectors or eqivilent plus matching MAF
-89-93 SC came with 30# injectors and 55mm MAF
-94-95 came with 36# injectors and 70mm MAF
-all cooling hoses
-SC thorttle cable
-SC throttle cable bracket
-MUSTANG wiring harness
-wire to lengthen wiring harness connectors
-extra cooling hoses for custom work
-MUSTANG timing chain cover or 94-95 SC timing chain cover
-MUSTANG crank sensor
-MUSTANG or SC alt will work, MUSATNG better sicne it has the extra connect on it, but will work without it for the SC alt, need to change pulleys if using the Mustang Alt. I believe the Mustang alt is more powerful as well, not exactly sure.
-SC AC compressor
-custom AC lines
-custom air inlet needed
-SC intercooler should work, not sure how well the SC intercooler tubes will clear but they should
or use a custom IC setup like me

-Mustang motor mounts
-SC valve covers
-Mustang DIS module, don't need the SC one.
-SC oil cooler (not needed but good to have)
-Mustng rad will work, but if using the SC IC then might be easier to us ethe SC rad its a little smaller though but works for the SC guys fine.
-Major tuning
-SC coil pack bracket (mustang coil pack should work but I have the SC coil pack as well)

Now, how hard it is?

Well that all depends, if you have the complete motor it will be a lot easier, basically just drop the motor in and customise the wiring and hoses and a few other things. Finding all the needed parts is the hard part, where as a complete motor has everything you need.

A lot of custom work is needed to get everything hooked up, I had to make custon cooling hoses where the heater core is, I had to cut the throttel cable bracket to clear the hoses so I could not use the cruise control cable, so no cruise. The EGR needed to be deleted sicne there is very little room where it hooks up, the engien is very close to the firewall, I may try and get it to work with customising the EGR just for emissions, not sure yet. You will also need a very good tune to make this setup work, trust me, I have been there.
You will need to make a custom air inlet from the airfilter to the TB, thats not too hard, also if using a custom IC setup, then thats all got to be made as well, piping, brackets IC etc. The SC motor has 2 extra sensors they are the knock sensor and oil level sensor, we can live without these, and besides our mustang harness will not plug into them so we can't sue them anyways, all other sensors will work, just need to lengthen wires to reach them. With my custom IC setup I had to moive my battery to the trunk as well, but if you use the stock SC IC then you'll be fine.

How will my mustang block hold up?

Well the SC came with a stronger crank, pistons and rods to handle the extra power. The SC block is also stronger. The mustang block has proven itself to be fairly strong as well, no one has broken one yet at least. No one really knows for sure how long the mustang pistons and rods and crank will hold up to the roots setup, I have been told that the rings would be the first to go, the mustang has a higher compression ratio, but something about the location of the ringlands or something is better ont he SC pistons, don't wuote me on that, its hearsay right now. Stock SC compression is 8.5:1, I am running 9:1 with forged pistons in my setup. I have heard about guys even running above 10:1 with the roots blower but I don't think they push their motors too hard either, more for show.

I have also heard of guys runing 4.2 SC motors, with no problems, except for one guy who keeps busting cranks, SC cranks at that, I think his problem lies elsewhere though.


Q: is there a way to keep the cruise control AND the air conditioning?
A: SC's the throttle and cruise cables run behind the intakes where the mustangs run over the intakes. I had to cut the mounting bracket to clear the heater core hose inlet/outet from the firewall, its not the cable thats the problem its the bracket that holds the cable to the TB.

Q: I'm thinking of putting an M90 setup on my 96 Tbird 3.8. Will the M90 stuff bolt right up to my intakes, TB, radiator, tranny cooler, etc? Is the M90 a direct bolt on or do I still need to change alot of stuff?

A: No, the intakes, throttle body, and radiator will not fit. The stock Supercoupe setup includes a specific intake hose, throttle body, inlet plenum, M90 blower, intercooler and piping, shorter radiator to fit next to the intercooler, a return plenum, and lower intake manifold. So, yeah, there's a lot more to it than just a blower. Some of the intercooler stuff can be custom made to work with your stock radiator, but the rest will have to be changed.

Q: Do you use the mustang wiring harness when doing this swap? What about the barometric pressure sensors? my mustang harness does not have provision for them with 89 super coupe motor in 94 mustang

A: don't worry about the BAP sensor. Your basically adding a blower to the mustang motor, even if you use the SC complete motor. The computer is still the stang computer. So it just thinks you added the blower. Plus the SC computer is an OBDI computer and the stang is OBDII which is better. You just don't use a few sensors the SC had. The SC was a luxury sports car and had so many extra sensors, like air ride control coolant level etc etc etc.

Q: Can i use the mustang idle control valve on the sc t.body?
A: Yes, in fact, you should ONLY use the Mustang IAC. This also avoids splicing a connector

Q: on the air temp sensor do i use the mustang or tbird sc part. if i use the tbird piece can i use the mustang connector?
A: yes, again, only use the Mustang sensor
Different ways of mounting a rad and intercooler

First off you can use the stock SC rad and IC, might be the easiest way too, since the IC tubes will all line up as well as the rad hoses. I have heard you just have to slightly bend the brake lines out of the way for the lower IC tube since it comes close to the master cylinder brake lines.

The great thing about the SC rad is its a 2 core rad, if you get the older style SC rads theyahve brass end tanks, which means they can be re-cored to a 3 core rad, so make sure the SC rad has the brass end tanks. The newer style had plastic end tanks, they look the same though I beleive, just one is brass and one is plastic.

I used the base of the SC throttle plate and the end of the mustang. Just cut and welded and everything works fine. Im not happy with the long cables and trying to find shorter ones. It looks like the throttle cable from a 2k Taurus is about 2'' shorter and should work great. I think i will just re-mount the crusie control module down further in the fender to help shorten it. Sprout send me the other lings so i can post them.
the supercoupe waterpump will not work on the 96-98 mustang's timing cover, I just found this out today, as we're swapping one onto a local member's car and it doesnt match up. And the mustang water pump's bypass tube interfere's with the supercharger belt, so we have to figure something out. Might end up using a tbird water pump
the bolt-pattern of the supercoupe water pump is just slightly different from the mustangs, or at least the 98's. And with some modifying of the metal tube the 98 mustang has that goes into the water pump and the use of a 6 rib supercharger belt it will clear, but it's a big pain in the ass.
SC water pump bolts to a 94-95 mustang timing cover, not to 96+ FORD changed the water pupm and timing chain covers in 96.
the mustang TPS wires are identical to the SC wires only different colors, y this I mean they attach int he exact same order, the middle wire is the easiest to get correct, its the two end wires that you can get mixed up.

Mustang - SC

Brown/White - Orange/white
Green/White - Greeen/Light Green
Grey/Red - Black/White

On mine the Brown/White wire ont he Mustang harness also looks Black/White, kind of hard to tell.

The IAT sensor is on the return plenum right before it enters the lower intake correct. I didn't change that sensor, I just lengthened those wires so the mustang sensor would reach.
#1 – Connect #6 hose to this fitting

#2 – Cap off this one

#3 – PCV Valve (on drivers side valve cover)

#4 – Boost Gauge

#5 – Use a T fitting...one to the FPR (on fuel rail, silver thing at the
back on the passenger side) and one to the BPV (bypass valve that connects
both intakes)

#6 – One hose goes to #1 and the other goes to the brake booster



4,5 and 6 in this pic hard to see

It should be noted that this intake piece and the hose fittings 1 thru 3 vary slightly depending on what year SC it came from.
Also, I don't know if it matters or not but in the stock SC setup, the vacum line from the bypass valve runs to the inlet plenum (pictured above) and not the return plenum as noted in the post above as fitting no.5
You can see it connected here in the very most top /right corner of this picture.

Also,, #6 is a "T" and needs the large line from the brake booster connected to it.
And,, for those people that retain the EGR needs to run off the inlet plenum as well.
contact Justin at VMP Tuning Inc he can set you up with a great tune, get an xcal2 and he can ship it to you with a few tunes in it already, he can get the tune almsot perfect this way, then when you get a chance get a dynotune to perfect it, but like I sid Justin will be very very close on his first try, he has tuned many Supercoupe swaps including mine.
use your Mustang MAF don't use the SC MAF. Your tune will reflect the Mustang MAF.
the SC lower will bolt up to any 94-98 Mustang, but if its a 96-98 Mustang you need to use the 96-98 lower intake bolts cause they are different, plus the 96-98 use 2 less lower intake bolts so 2 holes will not be used on the lower intake.

As Thomas said you need a 94-95 Mustang or 94-95 SC timing chain cover no matter what year the motor is, this is due to the crank sensor on the Mustang and the water pump from the SC.
The heads will fit on the 99 block. You will need to use head bolts that were designed for the 99 block, Ford has changed the thread depth in the block several times over the past decade.
You're going to need a tune no matter what, before you even THINK about driving the
As for the injectors in general, you will need saturated / high impedance injectors. All the recent Fords have this type. As an example, the Thunderbird Turbo Coupe came with 36lb injectors, but they are low impedance. They are brown colored, which sets them apart from the 94-95 Thunderbird Supercoupe 36lb (dark blue) injectors. Using low-impedance injectors in a system designed for high impedance injectors will probably destroy the ECU.
On my setup I needed a couple feet of 3/8 hose and a universal adapter to connect it to the valve which is like 1/8. I then got a variety pack of vacuum caps to cap off the other stuff.
You HAVE to use the SC fuel rail
You need the head bolts to match the block. The depth of the counterbore/block threads is what changed. I.E. the later blocks need longer bolts.
Follow the torque procedure for the block year. Yes, you can use the SC gaskets. Some people only use those. But like Roadhawg has, you can use the MLS gaskets, which MANY folks, including me, will tell you are more durable
If you pop the SC gaskets, go ahead and get yourself some head studs when you put in the MLS gaskets. The studs are resusable
will the 96 mustang cps (cam position sensor) assembly work with the 94-95 mustang timing cover and oil pump?
94-95 is different than 96-98.

One puts out a traditional "wave" signal, the other outputs a box-shaped signal
yes all CPS sensors will fit the timing covers, the sensors themselves change but the size of the opening the timing chain is all the same.
Yes. Just make sure that you swap the whole assembly, from the sensor plug to the oil pump drive shaft.

It will fit in the timing cover.

Do I need new gaskets for the lower intake?

- the stock gaskets are not reusable, so get a set from Felpro, they are not expensive, I have reused felpro lowers before, but never stock, they are cheap enough to buy never everytime though.

From the posts I've read, my '95 should be fairly straightforward with the wire lengthening/splicing, right? No special electronics or wiring beyond what is listed in the how-to?

- nothing major other then lengthening a few wires and splicing in the SC TPS connector.

What is stock SC boost? I see a lot of people doing 12-15, but I fear for the stock top end, no big deal?

- 10-12#'s is about stock, with an OD pulley ont he blower you could see up to 15, but the SC's have a more restrictive exhaust so we actually see a little LESS boost, boost is just a measure of restrtiction remember.

From the pictures, it looks like the SC tubing has proprietary connectors, what do I need for custom tubing/connections?

- the SC intercooler tubes have specific connectors yes, if you go to an aftermarket IC, then you can run rubber couplers, just have to remove the factory coupler on the blower hat.

I couldn't quite figure out whether or not its necessary or just ideal to swap in either the SC fuel pump or an aftermarket unit?

- upgrade your stock pump to a 255lph Walbo pump, don't use the SC pump.

I'll delete the EGR to make it easier since we don't have smog here, but how do I cap off the manifold where the tube screws on?

- cut the nut fitting off the EGR tube, and have the hole welded shut(where the tube went through) then you can just use it as a cap.

Do I need any new o-rings or anything when installing the injectors?

- if they look bad then yes replace them, if not then they are fine to re-use, I believe when you buy the lower intake gasket kit, you get new o-rings with it.
Are there any options to underdrive the blower?
I measured the ID of the blower and return plenums to be close to 2 3/8 I think it was, would 2.5" OD pipes and an FMIC of at least the same surface area as a stock SC IC be sufficient?
How would one go about relieving fuel pressure before taking fittings apart?
I saw Sprout post something about lifting a head under WOT, but I know he is running more than stock boost. I have a 2.5" MAC catted H ready to go in as soon as I can drive it to the shop to have it installed along with a couple Flowpaths. I'm hoping that will help with the boost, but I still want to be cautious about using the N/A block and heads.
the 94-95 pulley will slightly underdrive it 94-95 PULLEY IS ONLY A 3% UNDERDRIVE
Another site:
The 94-95 SC engines were upgraded. The plenum was improved, the rotors were Teflon coated for reduced temperature, and the throttle body was enlarged to 70mm from ~60mm to match the plenum. The 89 style received 30lb injectors and the 94-95 is 36lb with a better fuel pump. The setup was so more efficient that Ford put on a larger blower pulley to achieve the same boost levels that the previous models had received, and got a little more power. The 89-93 models were rated at 210hp/315tq, and the 94-95 were 230hp/330tq.

Most people end up finding the less efficient style for the swap. If you decide to run the stock 30lb supercoupe injectors, you will be limited to about 265whp and 350tq – not too bad.

The stock boost is between 10-12 PSI, which depends on how well the engine flows. Of course, you have a large array of pulleys to choose from to put on your setup. An OEM 94-95 style on an 89-93 blower will reduce the boost 1-2 PSI. Conversely, an 89-93 OEM pully on a 94-95 blower will raise stock PSI by 1-2. Overdrive pulleys are available for each kind. One just has to use common sense; the 10% 89-93 style overdrive pulley will obviously be the smallest (the one in my engine picture). More overdrive is not necessarily better, as the already weak intercooler and crappy flowing parts get heat-soaked quickly. I wouldn’t even bother with a 10% on a near stock engine due to the immense heat increase that would negate much of the gains over the 5%.

More info: (mainly single port stuff, but important information as well)

Assuming you are just doing the swap onto your stock short block, you MUST upgrade the injectors and fuel pump. You MUST have dual exhaust at a minimal, or you greatly increase the chance of head gasket failure. The 94-95 V6 mustangs are a little easier to swap because the 96-98 changed a few things. The 94-95, however, should definitely consider using the supercoupe heads. The valvesprings are stronger, it flows a little better, but most importantly, it has improved cooling passages which greatly decreased head gasket failure (95 stangs had a recall). The supercoupes had head gasket problems as well, but this can be attributed to their stock exhaust system. It was terribly designed with a 90 degree bend and poor flowing parts... which netted an end result of 15psi of backpressure. Thankfully, a simple GT take off system will due for our cars, and we basically have shorty headers straight from the factory (as opposed to the SC's log style manifolds). Other than fuel and exhaust, we need a tune to go along with it after everything is assembled. These are the only NECESSARY factors; cam, rear end, high stall, clutch, etc will simply compliment the setup. Obviously, with an engine of this power, stock parts are more likely to break. If you have the ability to upgrade things while you’re in there, do it. Preventative maintenance is a good thing.

Another Site

How to supercharge your 94-98 Mustang (M90)
First of all, I am telling what my experiences were on my project:

This set up is out of 89-95 t-bird supercoupe, which was a 3.8 with a supercharger. it is easiest to buy a supercoupe itself to get all of the parts needed, but is do-able without. The supercoupe motor came with forged rods, but cast pistons, MUCH stronger main caps and bearings; but is similar to a mustang 3.8

parts that are needed to do the swap: (off a supercoupe)
lower intake
intercooler piping and intercooler
intlet to back of intake
plenum from tb to blower
jackshaft and alternator bracket
timing cover from either a: 94-95 mustang 3.8 or 94-95 supercoupe
throttle body(one can be used from a 94/95 mustang gt, using gt throttle cable) or sc, using sc throttle cable
iac from sc
belts, hoses etc
at least 30lb injectors (89-93 came with 30's,94/95 had 36lb injectors)
im sure there are little parts that i am forgetting....

okay lets talk superchargers.. 89-93 are called "old style"(10-11lbs of boost), 94-95 are called "new style" and are much more efficient and make more boost (12-13lbs)

air conditioning... yes, you can actually keep your a/c!!!!! you have to spin the compressor 180* to fit on the sc bracket, and then drill and tap two holes into the bracket. i did mine without breaking my lines loose and ac works great. you also use the sc clutch. or, you can break the system loose and buy supercoupe lines and those supposedly work from what i hear.

clearances...... one brake line has to be bent pretty tight for the return air piping, but is doable. alt. bracket can be clearenced just a bit to fit mustang alt, which puts out more juice than the sc, and you dont have to rewire anything in regards to that. im sure i am forgeting many other things, but dont be afraid to break out the grinder

wiring... you have to extend some wires, mainly the inlet tempature sensor.

intercooler. you can run the stock intercooler if you run a sc radiator (very small) or run a custom front mount intercooler which will cool boost much more than the stock set up.

a stock early model supercoupe swap will make about 220hp and 325 ftlbs of tq. very fun set up and easy to modify to make more boost or more efficient power.

of course, a tune is crucial to enjoy without blowing up a set up, and Justin from VMP Tuning has a special supercoupe tune that i ran and didnt blow up, so it must be decent.
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Jan 26, 2008
Just outside Philly PA
Dayco Belts
Jackshaft.... .......5070425
Supercharger......5080393 (stock)
.........…..............5080390 (10% pulley)

M90 and Associated torque specs
Supercharger retaining bolts (8mm)- 20-30 nm 15-20 lb-ft
Supercharger retaining bolts (12mm)- 70-95 nm 52-70 lb-ft
Supercharger outlet adapter bolts/studs- 20-30 nm 15-22 lb-ft
Throttle body assembly retaining nuts- 20-30 nm 15-22 lb-ft
Intake elbow bolts- 8-13 nm 6-9 lb-ft
Intercooler tube retaining nuts- 20-30 nm 15-22 lb-ft
Intercooler outlet tube to bracket bolt- 40-55 nm 30-40 lb-ft
Supercharger adapter collar nut- 200 nm 148 lb-ft
Intercooler outlet tube bracket (to block) stud fully seated,
then 2-10 nm 17-88 lb-in
Intercooler outlet tube bracket (to block) bolt- 70-95 nm 52-70 lb-ft
Intercooler outlet tube bracket (to block) nut- 20-30 nm 15-22 lb-ft
Intercooler retaining (to radiator airboot) screw and washer assembly-
4-6 nm 3-5 lb-ft