The 4.6 and 5.4 are 100% fully interchangeable between each other.

If you think of the 5.4 to the 4.6 as the 351 windsor is to the 302 windsor. The main difference between the 5.4 and the 4.6 is the block. The 5.4 block has a taller/wider deck. But,.. the same pistons, same heads, rods, crank,.. all interchange. 4.6 manifolds will work on 5.4 block but you need the adapter plates,.. and now there are like 3 or 4 different companies making the adapter plates,.. so if you wanted to do a 5.4 2V PI motor with a Bullet intake or other Mustang intake it is now more easier then ever. If you want to make some real HP,.. you would find a Navigator 5.4 DOHC long block and then use either a Mach1 or 99 - 01 Cobra intake and with some work you can have a 450 RWHP NA motor using stock internals.

Typically the 4.6 2v NA will max out around 300 - 330 HP and 325 trq. Using bolt ons, cams, porting and exhaust. They can make more,.. but require lighter forged rods and pistons,.. blueprinting and some trick head and valve train work and spinning the motor to 8000 RPM. Realistically dont expect to make more then 275 - 300 RWHP out of your 4.6 with out nitrous or some kind of FI. The biggest downfall to the modular engines is their bore to centerline ratio. A Harley Davidson has bigger pistons then a 4.6/5.4.

Hurst