3.8 To 5.8 Swap

TeamCaffeineGT said:

You'll need the F150's wiring and ECM unless you are going to go the carburetor route. You would then need an ignition controller from MSD or the like. Motor mounts from a 95 Mustang GT as well as the oil pan will be needed to fit the SN95 K-member. The cooling system will also need to be upgraded to a bigger radiator. The transmission is another consideration. I believe the manual was a T-5 in the 95 GT, if you are going auto, then it will need to be a C4 or an AODE I believe. The front suspension will need to be upgraded to GT springs as well to support the additional weight. The exhaust will need to be a custom setup as the deck height on the 351 is taller than the 302, rendering the down pipes for a 95 GT useless. You'll also want to upgrade the 7.5 rear axle on your V6 to an 8.8 unit out of a GT.

Hope you are a wiz bang mechanic and awesome with electrical because this project is gonna take some know how and a considerable chuck of time to complete.

Best of Luck!

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TeamCaffeineGT said:

I want to be forthright and tell you that I have not performed this swap, however I have a pretty good idea of what you will need to get the job done. You can either source the parts needed from a salvage yard, or purchase them online.

Parts Needed
Mechanical:
94-95 Mustang GT 302 Oil Pan and Pick Up
94-95 Mustang GT 302 Motor Mount
Fuel Pump (the V6 fuel pump might work, but it should prolly be upgraded)
Transmission T5 or C4/AODE (not sure if you currently have an auto or a stick, but it most likely won't work with the 5.8)
Speedometer cable/Sensor (this will need to work with the 2000 Mustang's setup)
Exhaust System (Custom fabbed down pipe will be needed as the 5.8 has a higher deck height than the 302 in the 94-95. I don't think the 94-95 H pipe will work.)
V8 Coil Springs
Radiator Hoses (Not sure if the 96 F150 and the 94-95 Mustang GT uses the same hose setup)

Electrical:
Option 1: Transplant the 96 F150 ECM and wiring harness into the 2000 Mustang. (Have to tie into ignition, fuel supply and gauge cluster. Most Technical)
Option 2: Source a 94-95 Mustang GT ECM, PATS and wiring harness for the transplant (Less wiring and more plug and play. Best Solution IMO)
Option 3: Utilize aftermarket fuel and ignition management such as F.A.S.T and MSD or the like. (Most Expensive, but most Tuneable)

I did a bit more digging and the 2000 Mustang V6 Radiator and the 94-95 V8 Radiator is the same, so you shouldn't need to worry about this. The parts listed above will get you a good start and will get the engine in the car. The little things that you will have to look out for are things like:

Throttle Cable and Cruise Control Cable adaptions
Fuel Supply Line Adaption (Returnless versus Return Style?)
Air Filter Box/CAI Fabrication
Vacuum Line Plumbing

This is definitely quite an undertaking and I can guarantee that I didn't think of everything. If you can get this swap done before the snow falls, I would be super impressed. It took me roughly a year to get my 5.4 DOHC swap done into my 01 GT. Granted I have a wife and kids, full-time career, school, honey do lists and the like. I would estimate dedicated time, I could prolly get the swap done in 80-160 hours. You mechanical ability sounds very proficient, so I imagine you would be on the lesser side of that estimate.

The thing about an engine conversion is that you just need to get into it. No one can tell you that you need X, Y and Z and cover everything. The best thing to do is to get the engine sitting in between the strut towers and then go from there. It's part of the fun to just go for it and then make it up as you go!

Best of Luck to you! Let me know if there are any questions that I can help with! I am sure that once you are underway with the project, others will pipe in from the forum community as well.

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