Originally built by Montune in 1999, the YC Zetec engine is a turbocharged (with no street equivalent) version of the Ford Zetec E 16V engine. Cosworth took over the engineering and production of the YC Zetec in 2000.

Many interesting features are included in the new unit. To improve weight distribution and air intake conditions the engine is inclined by 25° to the rear as compared to the street versions of the Focus.

The turbocharger used is a TR30R Garrett AiResearch unit which was developed specifically for the WRC Focus. The TR30R is a race derivative of the "old" Garrett T3 turbocharger but uses an extremely expensive Mar-M 247 (this nickel-based super alloy is a trademark of Martin Marietta Corporation which became part of Lockheed Martin Inc. in 1995) turbine wheel instead of the INCONEL alloy turbine of its predecessor and has revised geometry to better accommodate the 34mm intake restrictor. All turbo calculations and dimensioning were done with an integrated 34mm restrictor as specified in FIA regulations.