going from the 1.4 or 1.6 to the 1.8 or 2l units (and their varients) is more invloved than say 1.8 to st170 or rs because the engines are differnet designs. inlet and exhaust are the other way round and coolant hoses and mounts are different. its not impossible, far from it but just a bit more involved. as proof have a look at my mates focus. he's in the latest fast ford with his black focus, started life as a 1.6 ebony now with rs conversion. his names Alex Whitlock.