Will a Ford 5.4 engine fit into 2000 Crown Victoria Police Interceptor without substantial modification and if it will can the stock automatic transmission handle extra power?

No, a Ford 5.4L engine will not fit into a 2000 Crown Victoria Police Interceptor without substantial modifications. While both are Ford products, the 5.4L is significantly larger and heavier than the stock 4.6L in the Crown Vic. The engine bay simply isn't designed to accommodate it. You'd need to modify or replace numerous components, including:

* Engine mounts: Completely different mounts would be required.

* Wiring harness: The 5.4L's harness is incompatible.

* Exhaust system: The exhaust manifolds and piping would need to be custom-fabricated.

* Cooling system: Potentially a larger radiator and different hoses.

* Power steering lines and components: May need modification or replacement due to clearance issues.

* Air intake system: Likely requires significant modification or replacement.

Regarding the transmission: Even if you *could* fit the 5.4L, the stock automatic transmission is *highly unlikely* to handle the extra power reliably. The 5.4L produces considerably more torque than the 4.6L, putting significant stress on the transmission, potentially leading to premature failure. You'd almost certainly need a stronger transmission, likely requiring a complete swap to a unit designed for higher torque output.

In short, this swap is a major undertaking, far beyond a simple bolt-in affair. It would require significant fabrication, custom parts, and expertise in automotive mechanics. The cost and effort would likely far exceed the potential gains.