EFP / Escort-Focus Performance
All the engines are similar in design and function but the 1.9/2.0L has a taller deck height to achieve the longer stroke. Many parts are interchangeable, many are not. There are at least 6 different piston designs and they must be used with the proper cylinder head casting. If not, clearance problems or low compression will result.
Larger valves are nice but very expensive to so as the pressed in valve seat must be removed, machined out, and a larger seat installed. Also the valve reliefs in the pistons must be machined to match the valves. In most cases, the added expense is not worth the small amount of power gained. Without proper porting, the valves will not help at all. In an all out head, the floors of the exhaust ports need to be welded and the port raised. There is no short side radius to speak of even after porting and it hurts flow. As cast, there is a sharp 90 degree bend between the bottom of the port and the valve throat.
The lower assembly is reasonably strong for moderate usage. Of course forged pistons are necessary for any serious power attempts or when running over 50 hp of NOS along with a performance ignition system. You could make the bottom end a lot stronger by adding aftermarket connecting rods. These are not cheap for this engine as they usually custom made. Adding high quality rod bolts will help the stock rods live longer in a higher rpm application. If going this far, the rods and pistons need to be made differently than the stock design specs. The rods are too short for his engine to make good power above 6500-7000 rpm. A shorter rod creates more of an angle with the bore centerline and increases friction and cylinder wall loading. A longer connecting rod and a piston with a higher piston pin location will be needed. A longer rod will also give the cylinder head more time to start flowing and works better for high rpm with a smaller port head like most CVH's.