What are the differences (bar the obvious, ie capacity, pistons etc!) between the 1.6, the 1.8 and the 2.0? Are they all the same size on the outside? or do the 1.6's have smaller blocks etc? What about heads, are the port sizes different, and are they interchangeable between different capacity Zetecs?

My mate has a fiesta zetec S, and he's after about 180-200 BHP out of it for the cheapest outlay possible, I know vaan-aitken used to do a turbo kit for the car, but they are no longer selling it, and we we wondering about making a home-made turbo kit for it, as the 2.0 Zetec seems to be fairly easy to convert

Will a 2.0 Zetec fit into a fiesta without too much hassle? Orcan you bore the 1.6 Zetec to a nigger capacity?