Windstar Manifold How To: (Vortech Pics Page 5!)

6 Shooter

Well-Known Member
Just a thought for those with a Windstar upper intake and also using a blower and running boost pressures. A bank to bank air flow issue will occur with the Windstar intake itself which was specifically designed for a normally aspirated motor which sucks air. By design, the Windstar intake has no way to balance air flow from one bank to the other bank because each side is not connected to the other. Thus, there is no issue with an NA motor. In a boosted motor setup however, air is being pushed (not sucked) into the motor and the shape and angle of the intake tube before the throttle body will shove more air into the driver’s side or the passenger side. More air to one side or the other creates a more lean or more rich condition on one side of the Windstar intake vs the opposite side.

The best fix would be to re-work the final intake tube that connects to the throttle body. IF the intake tube was perfectly vertical before the last bend to enter into the throttle body, the air flow would be balanced from one bank to the other. This would require making the bottom of that intake tube long enough to where the intake tube would be exactly perpendicular to the plenums of the Windstar. Think of the shape of a the letter T, with the top of the T being the Windstar intake and the bottom of the T being your intake tube. If the bottom of the T has been skewed to either the right or the left side, more air will be pushed to one side or the other. Air entry currently coming in at about 12:30 to 1:00 o’clock, or the 11:30 o'clock position will cause bank to bank air flow imbalances. Pushed air needs to be coming in at an exactly 12:00 vertical position for the air to be balanced from one bank to the other.

Data logs show this issue clearly when the short term fuel trims from one bank to another show a difference above 3 percent of each other. The differences can be as high as 10-15% or more which makes for an untunable motor. This issue only occurs in the lower half of the throttle range when the motor is NOT running in boost and the PCM in closed loop is trying to fine trim the A/F ratios for smooth running.

6 Shooter

Well-Known Member
Just look at the STFTs at any one point in the data log when the throttle counts are less than about 50%. One bank may be showing 5-10% higher than the other or conversely 5-10% lower than the other. Think about how the PCM will decide which bank to trust or trim A/F numbers. For example, bank 1 may be 1.05 Lambda and Bank 2 could easily be 0.95%. Which way would you adjust the MAF to change the A/F ratio when the wideband is showing 13.2:1?? And, by how much??

6 Shooter

Well-Known Member
Thought of an easier fix to the Windstar upper in lieu of modifying the intake tube. Remove the Windstar intake and drill a 1/2” or better 5/8” hole in each end of the plenum runners. Get two 5/8” 90 degree brass barb fittings and epoxy the hell out of them into the Windstar intake holes. Make sure that the 90 degree elbows are facing each other. Connect the two barb fittings with a piece of hydraulic quality hose (300 psi hose) from a hydraulic hose repair shop. Clamp the rubber hose ends to the barb fittings. The imbalance of air flow will be neutralized by allowing a little amount of air to flow from one plenum (mainly the driver’s side back to the passenger side) continuously to equalize the pressure in both banks 1 and 2.

Think the fix would be under $25 and a lot less hassle than modifying an aluminum intake with multiple bends.


Boosted V6
Just look at the STFTs at any one point in the data log when the throttle counts are less than about 50%. One bank may be showing 5-10% higher than the other or conversely 5-10% lower than the other. Think about how the PCM will decide which bank to trust or trim A/F numbers. For example, bank 1 may be 1.05 Lambda and Bank 2 could easily be 0.95%. Which way would you adjust the MAF to change the A/F ratio when the wideband is showing 13.2:1?? And, by how much??
The dominant bank is bank 1 or bank 0 as it's written in my tune (cylinder 1,2,&3). If there is that much fluctuation between banks the ecu will disregard bank 2 o2 sensor and likely throw some codes. I think there is another issue you are having. I would look at vac leak, o2 sensor, or a bad injector. The stock mustang upper intake is very similar to the ws as each bank has it's own plenum, the mustang intake is just top entrance where the ws is fed from the front.

6 Shooter

Well-Known Member
There is one big difference between the two uppers--The V-6 Mustang upper has a large area at the back of the intake where the incoming air does a U-turn. In this area, boosted air can equalize a balance to some degree due to its large size. On the Windstar however, the incoming air hits a wall just behind the throttle body and must do a split, the area for equalization (balance) from one side to the other is probably about only 25% of the area of the Mustang upper. If the throttle body is removed on the Windstar, one can see two tiny Vee's sticking straight out toward the throttle body which helps air decide which direction to go to. If the incoming air is entering from a straight line into the throttle body, think the incoming air would be balanced, side to side. Now, if the inlet tube was coming into the throttle body at say the 1:00 o'clock position, more air would be sent to the drivers side than the passenger side. The reverse would be true if the inlet tube were aimed at the 11:00 o'clock position where more air would be pushed toward the passenger side.


Boosted V6
I see the picture you are painting but do not agree fully. Think of what's going on in that intake while the valves are opening and shuting. The pulsating air plays a big role in intake design also. One thing you could do is get the data to support your claim and I think the most accurate way to do this would be wire up a map sensor on each bank. I think a common and larger plenum volume is a good idea but only after a certain point. From all my data I believe the composite intake is done a little over 6000rpm due to insufficient plenum volume. I did the testing for vap some years back with a procharger and the gains I saw over the stock were pretty good.


Boosted V6
Mine runs very well.


New Member

Disclaimer: This is how I did my own conversion. There are many things that need to be fabricated so if you don't have the skills or the balls don't try this. Also there where a few things that I wouldn't consider the smartest thing to do to a car but were needed.

Tool List:
Full socket set
Drill + bits
Hole Stepper Bit
Vice or a clamp and table
Wire crimping/cutting tools
die grinder or other cut off tool

Materials List:
Cobra R hood
Manifold w/ isolator bolts
3/8" phenolic spacer
Gasket material (a must)
New upper gaskets (one for a stock upper and all for the windstar manifold)
EGR delete (a must)
Intake tubing (I used a 90 and a 45)
Intake hoses (too many to name)
Vacuum T's
2" wide aluminum plate
1" wide aluminum plate
2 Barbed 3/8" fittings (for remote IAC)
A tap for those fittings (1/4 NPT) maybe different depending on what you pick up
2' wire 3 different colors (for lengthening the TPS)
Various wire connectors

OK start by removing your EGR system. I had to cut the pipe close to the header with a die grinder so I could just put a socket over the end.
Remove the solenoids, pressure sensor, and valve from head. I pulled the wires back and zip tied them to the fuel rail. Then cap off the port on the head.

Next I deleted the PCV system by switching the pcv valve and cap from one side to the other. Them putting a vacuum cap on the driver side and a breather on the PCV valve on the passenger side.

After that was removing the stock upper manifold. This is pretty simple: first remove the air filter and tubing, then the throttle cables, next the vacuum lines, also the connectors for the TPS and IAC, on the coil pack just simply unbolt it, and finally the 8 bolts that hold it down.
NOTE: there are two fasteners on the back holding the wiring harness to the upper plenum.

So now your upper is off and the engine looks sad, I took this opportunity to clean the lower the best I could.

Here comes the fun (and stupid part). Even with a 3/8" spacer I still had big clearance issues with the bypass vent and fuel pressure sensor. I used a 1" ID conduit pipe to bend the vent towards the driver side headlight (pull very slowly and only a little at a time), Then used a flat wide bar and a hammer and hit the fuel rail on the fuel pressure flange twice to move it (this made me very worried). Next you have to remove the dowels for the lower and replace them with ones long enough to go through the 3/8" space and the new upper (mine were too long so I cut them with the die grinder until the fit)


After you get those clearance issues fixed It's pretty simple. Install the spacer with a new gasket under it. Them replace the gaskets on the Windstar manifold and Bolt it on (be careful as this manifold only needs 15lbs of torque to hold it down). I then Fabbed up some brackets to hold the Throttle cables, coil pack, and to remote mount the IAC. The IAC bracket is the only one I will go into detail as you can see the others and figure them out.


On the IAC I made a flange out of 2" aluminum plate from Lowes. Simply use a gasket and trace the pattern on the aluminum. Cut out the (outer) shape using a cut off wheel, hacksaw, whatever you have to cut straight with. then use the inside guidelines to find two places to drill for the barbed fittings. Next tap them and use teflon paste on the fittings.

With the TPS you have to lengthen the wires about a foot. Just some simple 14ga wire and connectors and that was done. Since I remote mounted the IAC I didn't have to lengthen those. I just mounted It with some zipties and was done. There is a vacuum port right behind the original IAC mount so thats perfect for you remote mount manifold side.

My biggest headache was the intake tubing! I bought a 3" 90 degree and wanted to run it to the stock hole in the fender support. That was impossible with what I had. I figured to run it under the frame rail and inside the splash guard.




I went and bought a 3" 45 degree and 2' of 3" coolant hose for O'reilly's and went to work. I made a vacuum port on the tract halfway down for the remote mount IAC. Then made a hole big enough for the MAF in the splash guard. (you must buy a new coolant reservoir)

Almost done! Just get the rest of the vacuum lines on, mount the coil (including the clip), and mount/fab some throttle brackets.

That was pretty much it!






Manifold w/ isolators 50
aluminum 10
throttle body spacer (optional) 35
Cobra R hood (optional) 235
egr delete 30
hoses 10
Intake 70

Total 440

Thats a high estimate if you have the materials laying around and dont want the hood its less than a hundred. I spent much more just because I bought a tuner, phenolic spacer, 70mm throttle body, and other things at the same time.
Very nice job

Clay Robinso

New Member
Starting to do swap. Keeping EGR. Using Windstar EGR housing. Done with that part. EGR swap has to be done in a given order unless you want to do it several times like I did.

EGR swap
1) Remove everything
1) Install Windstar EGR housing
2) Reinstall sensor located below housing
3a) Bend EGR exhaust line (Not easy)
3b) attach EGR solenoid to housing
4) connect up coolant tube
(Did not need to disconnect coolant tube to remove EGR, but EGR now sets lower and needed to disconnect to get to EGR bolts.)

Fitting manifold to lower intake.
1) Bend coolant tubing out of the way for coolant line to intake clearance
2) Bend fuel line out of way for fuel pressure sensor to intake clearance

That's all for now. But looks like it will fit under stock 2004 hood by just relocating AIC and an angled TB spacer.
EGR clearence.jpg Final check fit.jpg .


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