what is the biggest engine i could put in my 2001 ford f150 with a 4.2 v6 any help will be appreciated

 

Just which engine depends on what you want it to do and how much money you have. Got $10,000.? That would get you a nice 460 with cam, heads, headers, and a tricked up transmission. But it may be too much for the street depending on the exact configuration. If you intend to build a hot rod for the street, you don't start at the front of the truck. You start with the tires. What size are you intending to run? The bigger the tire the more torque you'll need, not HP. Next is what axle ratio are you going to run? If you have 31" tires and chose a 4:56 axle, engine speed is going to be tall which means a shorter stroked engine will do the job better- less piston velocity per stroke. Now what transmission will you use? A 4 speed manual? A three speed manual? A five speed manual? An automatic like a C6? An automatic with overdrive? Once you get all of this down, now you know what kind of engine you need. Just putting a big block under the hood and throwing parts at it is just going to be disappointing and expensive.