2.0-LITRE ZETEC E

FOUND IN FOCUS ST170

Although badged as a Duratec like the Fiesta ST’s engine, the 2.0-litre of the Focus ST170 is based on the Zetec E engine. Improved head ports and more adventurous cams than the factory 130PS-spec Zetec means the ST170 motor kicks out 170bhp.

It also features a trick variable valve timing setup on the inlet cam. This works well, with smooth power delivery and a good combination between fuel economy and power. A common mod that works in conjunction with the VVT inlet is to fit a vernier cam pulley to the exhaust cam. When matched to suit the inlet timing it’s possible to see gains of 10bhp from this one upgrade alone.

You can tune the ST170 using the naturally-aspirated route, and it responds well to a decent exhaust, air filter and remap. Like all Zetecs, a set of throttle bodies takes tuning to the next level and can provide a solid 250bhp-plus.

For the ultimate in power, though, you need to look to the US for a turbo or supercharger kit. A bolt-on forced-induction kit will work with an otherwise factory motor and can produce between 270 and 280bhp. You will need a decent engine management setup, which can add significantly to the cost but will also mean that you can fine-tune your engine to make the most of all the mods you’ve made.