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Swapping a 4.6 for 5.4 in a Grand Marquis?

Mercman76Mercman76 Posts: 3
edited October 2014 in Ford
Does anyone know or heard of hard it would be to swap out the 4.6 for the 5.4? I've seen people who've done it in magazines and such but I was wondering if takes alot of fabrication for the motor mounts and such.


  • A 5.4 should bolt in right in place of the 4.6. However, it will be a little wider, and a little taller, so you may have to cut the Y-pipe in the exhaust to get it around the 5.4 block. Also, the intake manifold on a 5.4 is a lot taller than the 4.6 manifold, and your hood won't close. There are low profile aftermarket aluminum manifolds for the 5.4, but for the life of me I can't remember who makes them.

    The 5.4 really doesn't make that much more horsepower than a 4.6. What it does have is a lot more low-end torque. If this is what you want, a 5.4 will fit the bill perfectly. If you're looking for more of a higher revving, high horsepower engine, a Marauder or Mk VIII 4.6 DOHC engine will probably be more your cup of tea.
  • euphoniumeuphonium Great Northwest, West of the Cascades.Posts: 3,425
    Does it matter to the onboard master computer. IOW is the old computer compatable with the new engine?
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