how hard is it to swap a navi 5.4 4v into my 2002 fx4 5.4. what is the problems in this how much power incress with the 4v motor.

 

It isn't a difficult swap-there will be some small exhaust modifications needed,and a bit of wiring to mate the engine to harness properly. The 4V 5.4L makes 45 more hp and 5 more ft-lbs over it's 2V 5.4L counterpart.
JL

 

Where is the peak power of the navi motor? Has it sacrifised bottom end to make more peak power?


Also how hard is just doing the navi head and intake swap as opposed to the entire engine?

 

Power and torque are only 300-500 rpms higher in the powerband. It'd be easier to swap the entire engine than trying to swap all of the top end.
JL

 

will it still work with the factory computer in my truck

 

You'll need to have it retuned to be optimal-the 4V engine has much more spark advance than the 2V. You can use the variable intake runner control circuit from the 5.4L to control the IMRC on the 4V-that will need to be adjusted in the PCM programming too.
JL