DETROIT - It's no surprise that Ford Motor Co. turned to Cosworth Technologies to develop the high-performance engine that will power the Ford SVT Focus. Ford has worked with Cosworth for more than three decades developing racing engines.
This time, though, Cosworth's task was to do more than wring more horsepower and torque from Ford's 2.0-liter Zetec four-cylinder engine. The powerplant had to be engineered to meet both U.S. and European emissions regulations because Ford plans to use it in the Focus ST170, sold in Europe.
Ford will build 20,000 units a year - 7,500 for the United States and 12,500 for Europe.
Meeting emissions regulations for both regions was a huge challenge, says Paul Ward, principal design engineer for Cosworth Technologies of Northhampton, England.
Cosworth Technologies is a powertrain engineering services company that is owned by Volkswagen AG's Audi unit. Ford owns the Cosworth Racing division, which it bought in 1998 when Cosworth was dismantled and sold by Vickers PLC.
The SVT Focus will mark the first time Ford has marketed a powerplant engineered by Cosworth in one of its U.S. models, according to Ford spokesman Said Deep.
Said Karl Kollin, powertrain engineer at Ford's Special Vehicle Engineering group: 'We recognized Cosworth's expertise with engine technology. They bring us a global viewpoint, which was important for this engine.'
Hot catalyst a priority
The conventional solution is to mount the converter close to the exhaust manifold.
But that strategy creates more exhaust backpressure, which reduces horsepower.
Using computerized tools that calculate the flow of exhaust gases, Cosworth designed a header-type exhaust manifold in which tubes running from each of the four cylinders merge into two tubes and then into one. The single tube feeds the catalytic converter mounted underneath the engine.
With a heat shield mounted on top of the exhaust header assembly, the catalytic converter reaches 80 percent efficiency within 1 minute of engine startup.
Faurecia manufactures the exhaust header, which is made from hydroformed steel tubes.
Cosworth was limited in the changes it could make. The high-performance engine will be built on the same assembly line in Chihuahua, Mexico, that builds the regular version of the 2.0-liter Zetec used in the Focus ZX3 hatchback.
To get a bigger charge of air/fuel mixture into the cylinders, the company enlarged the intake valves for the high-performance version to 33.5 millimeters from 32 millimeters and changed the spacing between the valves in the cylinder head. But the valve angle is unchanged from the regular Zetec, enabling both engines to run down the same line, Kollin said.
The SVT version of the Zetec also has a stylized engine cover that prompted engineers to relocate the lift points so that metal lift hooks on the assembly line wouldn't damage the cover he said.
The high-performance version of the Zetec makes 170 hp at 7,000 rpm compared with 130 hp at 5,300 rpm for the regular version. Torque increases to 145 pounds-feet at 5,500 rpm compared with 135 pounds-feet at 4,500 rpm for the regular Zetec.
Cosworth relied extensively on computerized engineering tools that measure fluid flow and mechanical stress to design and validate the changes it made to the engine, Ward says.
The union of the dual-stage manifold, variable-valve timing and exhaust header enables the engine to reach 85 percent of its peak torque at a low 2,200 rpm, which is a desirable trait for small engines.
Cosworth's Ward says key to making the engine overhaul work was that Ford brought Cosworth into the project from the beginning, about 30 months before the start of production, which is scheduled to begin late this year.