| Description and Operation The 2.0L Duratec ST engine is based on the 2.0L Zetec-E engine. In comparison to the 2.0L Zetec-E engine the modifications are: Cylinder Block part modified to include piston spray jets. Cylinder Head Inlet Port: - High flow design with new manifold break-out. Exhaust Port: - Standard port but with secondary air feed to the back of the exhaust valve. Water Jacket: - Revised flow around ports. Oil feed arrangement for variable valve timing installation. Incorporation of VCT (variable camshaft timing) solenoid in front camshaft bearing cap. Inlet Valves 33.5 mm diameter with revised spacing to maintain bridge material and longer length for new port. Exhaust Valves Standard diameter but longer to commonise tappet with the inlet side. Inlet Camshaft Increased lift and duration with variable timing. Trigger wheel fitted to indicate cam position. Exhaust Camshaft Increased lift and duration. Tappet Series of sizes commencing with unique graded part to suit new length valve and revised cam profile. Valve Springs Inlet and Exhaust unique parts to suit new valve lengths and revised cam profiles. Power Cell Assembly Piston with 20 mm diameter gudgeon pin. Connecting Rod - Forged fracture-split design. Top piston ring – Internal bevel to reduce blow-by of combustion gasses and negative ovality of the ring ends to reduce wear. Cam Cover Assembly Re-styled and revised to suit new VCT solenoid installation. Cam Cover and Gasket Assembly. Upper Timing Belt Cover Assembly Re-styled to include VCT pulley. Front Engine Mount Mounting studs moved to clear VCT pulley. Alternator Bracket Modified to accommodate revised engine mount. Intake Manifold Made up of two assemblies replacing the single piece manifold with fixed length tracts. - Housing Assembly-Manifold-Injectors
- Variable-length intake runner design.
The unit is in the short runner position with the engine off and then switches to the long runner position when the engine starts. The runners then switch to short runner position above 6000 rpm. Throttle Body Modified 63 mm diameter part. Injectors Increased flow items specified as 224.8 g/min at 2.7 bar (normal fuel rail pressure) Fuel Rail Redesigned part with integral damper and no fuel return connection. The fuel inlet to the rail has been repositioned requiring a new fuel feed hose assembly. Flywheel Assembly Dual mass flywheel. Clutch Assembly Friction plate – increased diameter. Pressure plate – increased diameter. Oil Cooler Modine type. Variable Cam Timing System - Variable Timing Unit Assembly
Oil Separator Assembly Internal changes to improve performance under high cornering loads – to be introduced onto base engine. Exhaust System Tuned 4-2-1 system with the catalyst located under the oil pan. | 
