A non-PI head has tear drop shaped intake ports. A PI head has more square intake ports. This is why a non-PI intake won't bolt up (without leaking) to a PI head.
The size of the combustion chamber is different.
Here's some more information about the differences between PI and non-PI https://www.americanmuscle.com/what-...or-intake.html https://www.fordf150.net/forums/viewtopic.php?t=94891 Whats the easiest way of identifying PI Heads? - Ford Mustang Forums : Corral.net Mustang Forum
It may be possible that your 2003 mountaineer has a PI Romeo instead of a PI Windsor. The differences between the Windsor and Romeo are really a "detail" as there are many people out here that have swapped Windsor motors for Romeo (including myself).
Consider that the 2003 Mountaineer will have a long runner TRUCK
PI intake. Which really needs to be re-used for the best results.
Doing some more research. The 2003 Mountaineer does not use (2) knock sensors. What it actually uses is (1) 4 wire knock sensor and (1) cylinder head temperature sensor (CHT). I think it's possible that one of the sensors that you think is a knock sensor is actually a CHT sensor.
There are TONS of possible donor PI motors in the salvage yards. IF your 2003 mountaineer is really a Romeo motor, then the donor could come from a 2001+ Ford Panther class car (Crown Vic, Grand Marquis, or Town Car). These motors are cheap and plentiful in the salvage yards.
IMO your replacement non-PI motor could be "free" and for your application this isn't a good deal. It's a big enough job to swap a motor as it is. Seems short sighted to go swimming with rocks tied to your feet.
Disclaimer: I have done (3) motor swaps in my drive way. As well as several 4.6 intake manifold repairs. I am not a professional mechanic. But I'm the kind of guy that HATES
doing a big job more than once. I would rather spend more $$ upfront to increase the chances of success on the FIRST try.
OBTW, one of the reasons why I came to own one of my project cars (2000 GT) is because the prior owner attempted to swap in a non-PI motor into a PI application. He got in over his head and had to sell his project at a fire sale price. His loss was my gain.
With proper planning this job should not require any tuning or fab work. It should be straight forward part swapping.
Anyway. Just my 0.02 worth. Good luck.
EDIT: Doing just a little more research using car-part.com an wiki the 4.6 in a 2003 Mercury Mountaineer has an engine VIN code "W" (8th digit of the VIN). That is the same VIN code used for the 2001+ Ford Panther. This should mean a SOHC Romeo 4.6 iron block.
Bottom line is the only real difference between the motor in the Mountaineer and any 2001+ Panther is:
- The wiring harnes. This swap MUST reuse the original engine wiring harness
- The front drive acc and cooling fan.
- The fuel induction including the fuel injectors.
- Most important. Swap the intake manifold!!!
- it may be necessary to swap the oil pan.
- STRONGLY recommend installing a new timing chain and guide if the donor motor has over 150k miles.
Basically put both motors on an engine stand and swap everything from the original motor to make the donor look like the original. But again this is straight forward wrench turning. Nothing special.