l have a 2000 Mercury Mountaineer V8 with the stock 5.0L in it. l love the power and it outruns most things on the road, but I am just looking to get some more out of it. So my question is, is it possible to swap in a Ford 5.4 Triton out of say a F-150. And if so is it an easy swap that l could do in a weekend or two in my garage. Or is it a swap that l could have done at a shop without spending too much money? l do not care about the legality or insurance implications of the swap. And if you think this is a swap l can do on my own do you have any suggestions or warnings about possible problems l will run into. When l dropping a normal 5.4 out of a late model F-150 and plan on spending some money getting some more power and performance before even dropping it in. Will this extra power cause havoc with my automatic transmission, or drivetrain? Is there parts out there for applications like I am doing? Has anyone done this before?
Not to be rude, to the first respones, but 2000 Mountaineers 5.0 had the following stats 214HP/288LbFt of tq. A 5.4 has 300HP/365LbFt of tq. l call that power difference fairly significant, plus in addition to spending a few hundred on some engine modifications that should add at least 50 to each category, all for what would run under probably 3,000 dollars. Makes sense. A 5.0L Ford Cammer crate engine with the same stats and performance costs 4,000.

You will need the entire engine transmission and electronic control unit to do the job right. If you are a proficient mechanic this is a do able swap. The mounts should all be the same, there may be wiring and plumbing issues to deal with.
However the power difference between a 5.0 and a 5.4 is not that great. l would do some modifications on the 5.0 to make it go fast rather than deal with a swap of this magnitude.

ABSOLUTELY NOT!!!!! If u even THINK about what u want to do u r only looking for TROUBLE!!!! First off, what model year of 5.4L r we talking about here? Are we talking about a a 2-valve, 4-valve, or the latest 3-valve here? To start with, before the 2002 & up models were introduced, Ford had already thought up of the idea of putting the 4.6L into the Explorer (same as a Mountaineer), & the reason they didn't, was because IT WOULDN'T FIT. A 5.4L V8 has a longer 4.125'' stroke & consequently, a longer deck height than the 4.6L at only 3.54''. With that said, what makes u think u r going to be able to fit a 5.4L into ur vehicle, if the Ford engineers could not even fit the smaller engine? Having the engine is the least expensive part of the equation. For example, it it is the 3-valve you're interested in, what r u going to do about converting ur return-type fuel system to the electronic returnless type that the 5.4 3-valve uses? That in itself, will be a VERY expensive proposition. What about converting ur conventional cable type accelerator to the 5.4 3-valve is ETC (electronic throttle control) set-up? How do u plan on wiring this thing up to work on anything, other than what it came out of? Replacing the CORRECT engine in a Mountaineer or Explorer, which is already a hard enough job as it is, already takes almost two days AT THE SHOP, so what makes u think u will be able to do it in weekend AT HOME? This is all besides the fact a 5.4 WILL NOT FIT IN YOUR CAR!!! l am sorry if l come across a little harsh, but l am just trying to save u A LOT of trouble. You will be better off selling ur vehicle, & buying the one with the powerplant u desire. Do not do anything dumb.

What she said, and to add, l would rather walk through Purgatory barefoot, drenched in lighter fluid, giving out popsicles than attempt this swap. Major modifications will be required and it will be an engine control and wiring nightmare.

Stick with the 5.0, not only for the reasons mentioned, but the 5.0 is a much better engine than that POS overhead triton thing anyway. Why not just buy a Power improved 5.0? There are many companies that offer 5.0 crate motors, some making well over 300 horsepower with the mods done to them.