1) have a read, the differences are quite obvious... different bore, stroke, compression ratio, ones normally aspirated ones forced induction, different port shapes, different port sizes, different valve sizes, different manifolds etc etc etc

2) 1/4 mile time isnt just down to the engine, its down to the car its bolted into, in your case its a fiesta which isnt renowned as being the best handling car, so your probably struggling with a poor chassis (assuming you have a mk3 fiesta) and poor suspension setup.

3) you cant have cossie management on your zetec as its not a turbo'd.

and which one of your questions do you class as really good ?