just wondering whats the difference between a focus 1.4 zetec silver top engine and a fiesta zetec-s engine as i want to fit the fiesta engine in the focus

just wondering whats the difference between a focus 1.4 zetec silver top engine and a fiesta zetec-s engine as i want to fit the fiesta engine in the focus

they are 2 different engines Early, ‘Silver Top’ engines (with an aluminium cam cover) were fitted to Escorts from 1991 onwards, late Fiesta Mk3s and then the Mondeo. These early units were known as Zeta (only becoming Zetec in 1993). The unit evolved into the Black Top unit (with a plastic cam cover) with the Escort phased out and Focus introduction. These later engines have longer rods and lower piston crowns, mechanical rather than hydraulic lifters plus the distinctive black cam cover. Initially there were 90, 105 and 115bhp 1800cc Escort versions, with 115 and 130bhp 2 litre Mondeo units too. There were also 130bhp RS1800 Fiesta/XR3i variations with revised cams and re-mapped ECU’s. The hottest n/a version was the ST170 with solid lifters, steel rods, waisted valves and variable valve timing (VVT). The motor went on to power the Focus RS but in turbocharged form. Both the ST and RS engines were confusingly re-badged as a Duratec.

It’s title is the Zetec SE but it’s also been labelled, as part of the growing Duratec series of late, plus it’s also called the Sigma in the US. However, it has nothing in common with any other Duratec or Zetec and no parts are interchangeable - confused yet? Told you!

The engine is all aluminium and designed in partnership with Yamaha. It is 16 valve and conforms to the current trend of interference fit/no-engine keyways, just like the Duratec I4. It also features a plastic inlet manifold, variable valve timing in the 1.7, solid lifters, aluminium girdle support unit incorporating the main bearing caps, steel crank and powdered metal construction con rods. Despite that almost worrying fact, they’ll rev to around 8,000rpm. For these reasons, they are being increasingly fitted in kit cars as a replacement for older engines.