Re: 3.8 to 4.6
As far as engine clearance/fitment, it will probably fit. You will need all wiring/electrical components as well as the ECU. Also is this engine mated to a manual or auto transmission, and what are you right now, manual or auto?
The 97 4.6L was SOHC, but it did not have the PI package: PI heads, more aggressive cam profiles and improved intake manifold.
The 96-97 4.6L's were rated at 215 hp and 285 tq.
The PI 99-04's were rated at 260 hp and 300-2 tq.
Honestly, with the 97 4.6, you wouldn't be that much ahead of a 99+ 3.8 regarding hp. The main advantage of the v8 is the torque and v8 sound.
If you can get the engine for next to nothing, it might be worth it...if not, I would say the swap would be more hassle than it's worth. Those years 4.6L's require quite much more effort to make power. Of course a +99 pi head swap would level the field...
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