I have a 94 f150 with a 5.8l 351 which is pretty much done. Was wondering how difficult or expensive a swap to a 5.4l would be.

 

I'd rebuild the 351. Better engine, and a lot less work than swapping in 5.4. 5.4 would need a different wiring harness, the PCMs and there is the question of mating it up to mounts and transmission.

If you are a masochist or a "see, told ya!" kind of guy, do the 5.4. If you enjoy having a running truck with a lot less effort, rebuild the 351.

 

You would need the 5.4 PCM and wiring harness to go along with the engine, or you can run the 4.6 PCM setup and have it tuned on the dyno.

So is it difficult? Not if you've worked on motors before lol.

 

Less money would go into getting the 351 bored over and rebuilt. But if you go to a 5.4 you have to run that PCM and wiring harness, but gain a metric s*** ton of modern tuning capabilities, plus it's a MAF engine.

Do you want to make it as good as it was before with minimal cash outlay? Rebuild the 5.8. If you want access to better tuning and MPGs, go 5.4

 

http://www.fordracingparts.com/parts...tKeyField=9190

 

Ok thanks I am pretty much after a little bit more power

 

The swap will gain a ton of power over the 351, but will be much more expensive and time consuming, with running the wiring, tuning the PCM and shoehorning the 5.4 in.

You could get a good bit more power out of the 351 as well while rebuilding with a hotter cam, better heads and a good exhaust package.

Speed costs, how fast do you want to spend?