|The 2.0-liter engine will be one of the first on the market to combine gasoline direct injection (DI) with twin independent variable camshaft timing (Ti-VCT) and E85 flex fuel capability. Click to enlarge.|
The North American version of the 2012 Ford Focus will be powered by a 2.0-liter DOHC I-4 engine with twin independent variable camshaft timing (Ti-VCT), direct gasoline injection and E85 flex fuel capability. The engine will be one of the first on the market to combine the technology of gasoline direct injection (DI) with twin independent variable camshaft timing (Ti-VCT) and E85 flex fuel capability.
The combination of these technologies help make the dual-overhead-camshaft (DOHC) Focus 4-cylinder one of the most advanced non-turbocharged four-cylinder powerplants Ford has offered. The engine is rated at 160 hp (119 kW) and torque at 146 lb-ft (198 N·m), up from 140 hp and 136 lb-ft in the 2011 Ford Focus.
Direct injection improves fuel economy and performance by delivering the precise amount of gasoline right into the combustion chamber. The advanced fuel injection system works in concert with Ti-VCT, which adjusts the valve timing for optimum performance, helping Focus achieve an estimated 40 mpg highway (5.9 L/100km) with automatic transmission.
As a DOHC design, the 2.0-liter I-4 uses two camshafts: one to open the intake valves and one to open the exhaust valves. Traditionally, camshafts have only been able to open the valves at a fixed point, defined during engine design and manufacture. But with modern variable cam timing systems, the camshafts can be rotated slightly relative to their initial position, allowing the cam timing to be advanced or retarded.
Ti-VCT takes this technology and applies it to both the intake and exhaust camshafts of its DOHC design, using electronic solenoid valves to direct high-pressure oil to control vanes in each of the camshaft sprocket housings. By using one oil control solenoid per camshaft, controlled by the electronic control module, each intake and exhaust cam can be advanced or retarded independently of the other as engine operating conditions change, providing an exceptional degree of valve timing control.
The overlap control via Ti-VCT helps us eliminate compromises in the induction and exhaust systems. Drivers will notice improved low-end power and better fuel economy. And there are benefits they won’t notice too, like reduced emissions overall, especially at part-throttle.—Jamie Hanshaw, Ford VCT technical specialist
With direct injection, the engine has a high 12:1 compression ratio, compared with the 2011 Focus PFI engine’s 10:1 ratio, further enhancing power and efficiency. The Denso solenoid fuel injectors are positioned to the side of each cylinder and spray into the cylinders at pressures of up to 2,150 psi (148 bar). The injectors have six outlets.
Other strategies to improve fuel economy in the Focus included reducing internal engine friction and reducing overall weight.
Computer modeling indicated areas where friction reduction strategies would pay the most dividends. The valvetrain received a fine surface treatment to present the smoothest surface possible. Piston skirts are treated with a special low-friction coating, and the oil pump and its drive ratio are sized for the exact capacity requirements of the new 2.0-liter engine.
Accessory drive friction was also reduced through a series of actions. Electric power-assisted steering (EPAS) eliminates the drag of an engine-driven power steering pump, while the use of so-called stretchy belt technology removes friction in the form of a belt tensioner on the air-conditioning compressor drive system.
Additionally, an overriding alternator decoupler—essentially a special pulley that reduces certain types of vibrations—allows the alternator and water pump drive belt to operate at a much lower tension than is typically used, further reducing frictional losses.
To keep overall powertrain weight as low as possible, the block, cylinder head and oil pan—traditionally the heaviest engine components—are aluminum castings. To increase rigidity, these elements are ribbed for additional strength and durability. Pistons are cast aluminum as well, with the light weight helping to reduce reciprocating mass.
Composite material is employed to keep intake manifold weight to an absolute minimum, while allowing for induction routing to increase thermal efficiency and improve low-end torque characteristics.
The engine will be manufactured in Ford’s Dearborn, Mich., Dearborn Engine Plant.