03-04 Cobra Motor in Expedition

[RBPowered]

Originally Posted by Stillen GLE exactly, I am just wondering If Id be able to use the 5.4L Wireing harness with the 4.6L if I decided to swap that in. I built the Turbo Expedition that's on youtube so I have pretty much all the answers to these questions. Yes, you can use the 5.4 wiring harness with the 4.6. You just have to modify the harness so that everything plugs in. All the components of the 4.6 and 5.4 are the same. Like injectors, coil packs, sensors, etc.. If the motor is n/a than all you need to do is install a set of 19 pound injectors, use the stock mas air meter and turn the key. It will run perfectly. As long as it's a Cobra 4.6 the flexplate from the 5.4 will bolt right on and the transmission will bolt right up. (you'll have to remove the pilot bearing from the back of the crank) You can use DOHC Navigator exhaust manifolds. You'll have to modify the exhaust slightly but that's about the best alternative. On the turbo Expo we bought shorty headers for a 4.6 Expediton from Summit, cut off the flanges and welded Cobra flanges on. The headers came out really nice and were a direct bolt on for our turbo system. (the turbo system was built on the stock 4.6 so we wanted it to bolt right back on with the DOHC setup) I'm in the process of doing another DOHC Expedition right now. Engine should be back in tomorrow. This one's not as crazy as the last one. Just used a '98 Mark VIII engine for this one. I did a full air ride setup along with 24" wheels. I'll post up pics when it's done. Here's a quick sneak peak:

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[tarajerame]

say what???? 19# injectors?? I hope that's just for the gentle drive onto a trailer and and then back onto a dyno


can't wait to see some more pics

[RBPowered]

Originally Posted by tarajerame

say what???? 19# injectors?? I hope that's just for the gentle drive onto a trailer and and then back onto a dyno


can't wait to see some more pics

Do the math buddy, 19 pounders are good for 304 at the crank. An N/A DOHC 4.6 is rated at 300. That's adequate at 100% duty cycle, which isnt optimal, but is doable and WILL run the engine just fine.

It's definitely a good way to get the swap going and work out any bugs before you need to flash the ECU for larger injectors, more fuel, timing, etc...

I'll be starting up my current project tomorrow, with 19 pound injectors in it. I'll throw the 24's back in and dyno tune it once I know it's good to go.

Here's another pic from the engine install today:

[Stillen GLE]

Thanks man, If I got a 4.6L expy, I could use the expy 4.6L harness for the Cobra 4.6L right.

But If I decided to go the 5.4L Route, I could take the wiring harness etc out of the Navi and plug it right into the expy for the in-tech 5.4L as well right.

[RBPowered]

Originally Posted by Stillen GLE

Thanks man, If I got a 4.6L expy, I could use the expy 4.6L harness for the Cobra 4.6L right.

Yes, the easiest thing to do is to take the 4.6 expedition harness, place it on top of the Cobra engine, and one by one, start shortening, lengthening or moving each plug until it connects to what it's supposed to. You need wire, solder, shrink wrap, electrical tape, a few different sizes of wire loom and about four hours of time and you'll end up with a factory looking harness without ever having to look at a schematic.

Originally Posted by Stillen GLE

If I decided to go the 5.4L Route, I could take the wiring harness etc out of the Navi and plug it right into the expy for the in-tech 5.4L as well right.

Yes, the Navigator harness should plug directly in. I have not done this myself so I'm not 100% certain but I have been through the schematics of the 4.6 and 5.4 and I believe it will plug directly in.


This is a great truck to do a swap in. You can find Expeditions for $2000 or less if you look hard enough and a '97 or '98 Mark VIII engine can be had for around $400. The other parts required for the swap, Navi manifolds, oil pan gasket, oil & filter, etc... You can literally buy the truck and do the swap for under $3000

If you go the 4.6 route you'll have to either install an electric fan, or swap out the water pump for an Expedition water pump to allow you to use the clutch fan. This will require modifying the water tube assembly that goes around the alternator. It needs to be shortened about 3/4" and the upper radiator hose outlet needs to be moved around the side a couple of inches.

You'll also have to do something about the bypass thermostat assembly. You can either use the bypass style that comes on the Cobra/Mark VIII or you can swap over the lower water neck/oil filter adapter from the Expedition and use an inline thermostat in the upper radiator hose. You'll still have to modify the water neck the same way except that you'll completely remove the bypass port on the water neck.

[RBPowered]

I also wanted to add that if any of you guys are doing this swap or any other Ford swap and you need to have anything in the ECU changed like the injector size, gear ratio, MAF calibrations or if you need the anti-theft disabled for remote start or custom installs into other vehicles or any other Ford computer mods for that matter, I can flash the ECU for $100. That includes the return shipping.

Just figured I'd throw it out there if anyone needs that service.

[Stillen GLE]

Thanks for taking the time to answer my questions, much appreciated. Ill probably end up using the Navigator 4v ECU, since everything would be plug and play, I could be up a Motor for a few hundred bucks at a junkyard right?

I though about a Lightning swap, But I am just looking to Daily Drive this and beat the piss out of it every once in a while. I though about Throwing GT Cams in It and being done with it. If I have to ill over haul the engine with Manley or Mahle Pistons, and change the Valves and port the heads as well.

[black02eb]

The 03-04 Navi harness is not plug and play, the earlier ones should be. I swapped a 04 DOHC Navi motor into my 02 4.6 Expy and had to modify the harness. I ended up merging both of the harnesses together, using some pieces of the 4.6 and some from the Navi. If you go 5.4 DOHC, you definetely won't be dissappointed!!

[Stillen GLE]

Originally Posted by black02eb

The 03-04 Navi harness is not plug and play, the earlier ones should be. I swapped a 04 DOHC Navi motor into my 02 4.6 Expy and had to modify the harness. I ended up merging both of the harnesses together, using some pieces of the 4.6 and some from the Navi. If you go 5.4 DOHC, you definetely won't be dissappointed!!

Yea I am looking at 98-02 Versions of Navigators and expeditions. so it shouldn't be an issue.

[tarajerame]

Originally Posted by RBPowered

Do the math buddy, 19 pounders are good for 304 at the crank. An N/A DOHC 4.6 is rated at 300. That's adequate at 100% duty cycle, which isnt optimal, but is doable and WILL run the engine just fine.

I misread, I thought you gonna run a turbo'd 4.6 with 19#ers

[black02eb]

Originally Posted by Stillen GLE

Yea I am looking at 98-02 Versions of Navigators and expeditions. so it shouldn't be an issue.

98 Navi's are SOHC 2v
99-04 are all the same DOHC 4v
The 03/04 had no IMRC, here is a pic of the difference...


The top one is an 04
The bottom one is an 01
The 03/04 engine harness plug that plugs in up near the battery is different to the 99-02. Otherwise they are exactly the same harness/engines.

[Stillen GLE]

Originally Posted by black02eb

98 Navi's are SOHC 2v
99-04 are all the same DOHC 4v
The 03/04 had no IMRC, here is a pic of the difference...


The top one is an 04
The bottom one is an 01
The 03/04 engine harness plug that plugs in up near the battery is different to the 99-02. Otherwise they are exactly the same harness/engines.

thanks man ill be using a 99-02 engine harness.