The Official Split Port Swap Thread

DISCLAIMER: In no way am I trying to take credit for writing this.These are the writings of SIXPACKSTANG from 3.7. I am merely reposting for everyone's general fund of knowledge due to the many people asking. The original thread can be viewed here: Sixpackstang's Official Split Port Swap Post

This is a very commonly asked question, so I did a write up with everything I could think of to help someone considering or doing a split port swap. I hope the mods will sticky this, it would help a lot of people out...

What are the differences between single port and split port?

To start we will discuss the differences between the 3.8 v6 motors. The 94-98 v6's are equipped with single port heads, lower intake, and upper intake; these have one intake runner per cylinder. On the 99-04 v6's, Ford switched to a split port design, which has two runners per cylinder.

From the factory, the split port design gave the v6 an additional 40hp, so some people with 94-98's like to swap their singleport heads and intakes for the split port. Doing this is a very custom setup, and there are some modifications that will need to be made. I will discuss these later.

What parts are needed for a split port swap?

Here is to the best of my knowledge a complete list of parts needed for a split port swap:

heres the parts list:
-97+ f-150 V6 heads or 99+ mustang v6 heads (including valves/springs)
-97+ f-150 v6 lower intake, or 99+ v6 mustang lower intake *
-99+ mustang v6 upper intake **
-99+ mustang EGR tube and valve (f-150 tube will work)
-99+ Throttle Body
-TPS sensor for TB (1-CX-1488 from Ford) if not already on TB
-Throttle cable from 99+ mustang v6
-Modified fuel rail that has a universal fuel pressure regulator, and a return line. (available from SteveC) ***
-Accelerator Bracket (F4SZ-9728-B) if not already included on upper intake
-99+ mustang v6 coil pack and wires (your stock coil pack will work too)
-99+ mustang intake tube, or any 99+ mustang CAI kit
-99+ mustang cooling hoses (including the ones going to the heater core) and pipes. You can also make your own lines, by using plumbing elbows,hoses and clamps, and fab it up yourself. (Definately get these if you can.)
-16 a.w.g automotive electrical wire
-teflon tape, pipe sealant, RTV
-99+ head bolts/studs
-head gaskets (I recommend 99+ mustang gaskets)
-99+ upper and lower intake manifold gaskets.
-99+TB gasket
-94-98 IAC gasket
-94-98 valve cover gaskets(reuse the 94-98 valve covers, valve cover gaskets can be reused if removed carefully)
-94-98 exhaust header/manifold gaskets
-you can reuse the 94-98 headers ****
-use the 94-98 IAC since the 99+ IAC has a different connector (Edit: I found that the IAC I used from a 99 mustang had the SAME connector. I am not sure about other years or F150's/windstarts, but the 99 IAC will work and I recommend using it for a cleaner looking install.)
-rad fluid, oil, filter, new spark plugs
-gasket remover, thinner to prep parts before applying new gaskets

* There are 3 different types of lower intakes you could use; these would be the 97+ F150 lower, the 99-00 lower, and the 01-04 lower. Each has its ups and downs, but I would recommend going with a 99-00 lower. Here are the differences:
The F150 and 01-04 lowers have IMRC's in the lower intake which will need to be removed, and the holes JB welded shut since the 94-98 ECU's don't have the ability to control these. The 99-00 lowers don't have these, and therefor you will have no modding to do.
The 94-98 lowers have 2 water temp sensors that go into the lower intake. The F150 lower also has 2 locations for these sensors on the lower, no problem there. The 99-04 lowers only have one water temp sensor and will need to be modified to work. You can do this by drilling/tapping a hole for another sensor in the lower before it's put on. There is a good spot for doing this and I will try to get pics later. Any machine shop could do this, and others have had it done for $5-10.
If you use an F150 lower, you will need to run custom cooling hoses. The F150 hoses won't work, and the 99-04 mustang cooling hoses won't work with the F150 lower. If you are using the 99-04 lower, the cooling hoses will fit and work fine.
My personal opinion would be to use a 99-00 lower, but all will work with some modification.
**There is a slight difference between the 99-00 upper intake and the 01-04 upper intake. The 99-00 upper has 4 holes for the coil pack to be mounted, vs. only 3 on the 01-04. If you can get the 99-00 upper it will be easier to mount your stock coil pack.
***The 94-98 mustangs use a return style fuel system, and the 99-04's use a returnless style. Therefor the 99+ fuel rail will need to be modified with a return fuel line. As noted above, SteveC on this board is again offering to make custom fuel rails for split port swaps.
****You can reuse the 94-98 headers, but you may run into trouble with hooking up the egr tube. I believe it mounts into a different location on the 99+ exhaust manifold and may not fit. You would need to have this customized to fit, or to use the 99+ exhaust manifolds/gaskets. I am not certain as I deleted the egr when I did my swap.

How difficult is it to do a split port swap?

A good bit of mechanical ability is needed to do this. If you don't usually work on your own car, this is not a good place to start learning. On a difficulty level of 1-10, I would rate this about a 6.5. You will be going pretty deep into your engine, and because it is a custom setup it can be tricky. From start to stop, this project took me about 3 full days of working (by myself though, extra hands would've helped at many points) plus driving to get odds and ends I didn't account for.

You will need basic tools such as metric and standard socket sets, swivel joints, extensions, wrenches, screwdrivers, a torque wrench in ft/lbs, (also a smaller torque wrench in inch/lbs is helpful but not necessary), wire cutters, butt connectors for the wires or a soldering gun, and plenty of patience. You will also need special tools for removing the fuel lines from the stock fuel rail. (AutoZone should have these)

There is also a video made by V6Sprout from that is a step by step guide to doing the split port swap. It is very helpful and I would recommend it to anyone doing the swap or even considering it. Watching the video could help you determine if you think you can do the swap yourself or not. (I no longer have or sell copies of the tapes. The copies were not turning out good and I sold my original copy to someone else.)

How much will a split port swap cost me?

This is just a quick list of what it cost me to do my swap. It may cost you more or less depending on where you get your parts. Places to look for parts? Try the for sale boards here or any other v6 site like Also ebay or a salvage yard might be useful.

-Heads, intakes, modified fuel rail, cooling pipes/hoses, most of the other small parts needed. I bought these for $500. A bulk of the cost here is in the custom fuel rail. I'm not sure what SteveC will be selling his for. Check ebay, junkyards, and the For Sale forums here and at for these parts.
-Throttle body, sensors on TB, throttle cable. $50
-99+ cold air intake. $50 (you can avoid this cost by using the stock 99+ plastic intake)
-Gaskets, head bolts, plugs, wires. $200
-Oil, filter, antifreeze. $30 (you can reuse your antifreeze if its new/still good)

Grand total around $800 for the complete swap.

This is all the information I have right now on doing the split port swap, and hope this helps you out. If you have any questions feel free to contact me and I'll see if I can help you out.

Mods: I think this would be a good idea to sticky this info. I put countless hours of researching all this info. from different sites and it was difficult to find answers for a lot of the little questions I had about different parts. There are tons of people making posts about how to do a split port swap etc. and I think this could eliminate them and help encourage more people to try this.