At the heart of the appeal of the next-generation Ford Focus ST is a high-output 247-horsepower version of the efficient and advanced new 2.0-liter Ford EcoBoost four-cylinder engine.
This unique EcoBoost engine is specially tuned for the new Focus ST to ensure the car gets the world-class performance - and the inspirational sound - expected of it. It also marks the first application of the four-cylinder Ford EcoBoost engine in a high-performance model.
"EcoBoost technology has fully lived up to its billing, offering owners power and performance with uncompromised fuel economy," said Barb Samardzich, vice president of Powertrain Engineering. "Combining EcoBoost with Ti-VCT on a high-performance small car like Focus ST demonstrates our product commitment to yet another audience that perhaps hasn't shopped Ford in a while."
Compared to the 2.0-liter Ford EcoBoost engine planned for other Ford vehicles, the Focus ST unit features redesigned intake and exhaust systems and a unique engine calibration to deliver the desired level of power and responsiveness.
The lightweight, all-aluminum engine design combines three technologies - high-pressure direct injection, low-inertia turbocharging and twin independent variable camshaft timing (Ti-VCT) - to create an advanced combustion system that brings new levels of performance and fuel efficiency to engines in this category.
The turbocharger increases airflow in the engine to boost power while direct injection helps enable more efficient fuel burn for better fuel economy. Just like the first-generation EcoBoost engines, the EcoBoost four-cylinder engine will spool up quickly to its maximum torque; in this case, 250 lb.-ft. across a broad rev range - estimated from 2,000 rpm to 4,500 rpm, according to preliminary Ford data.
"You get peak torque throughout the majority of the engine's operating range," explained Scott Makowski, Ford manager of North American four-cylinder powertrains. "It's available when you accelerate from a stop or merge onto the Interstate, and drivers don't have to wait for the rpm to build before they get exhilarating performance. There's torque - and a lot of it - whenever you need it."
Working with the direct gasoline injection system, a state-of-the-art turbocharger ensures virtually lag-free operation at all engine speeds. In service, the turbo spins at up to 195,000 rpm and is designed for a life cycle of 150,000 miles or 10 years.
Traditional turbocharger "whoosh" is mitigated by electronically controlled anti-surge valves that proactively relieve the boost in the intake, which can range up to 16 psi. Careful software calibrations manage the pressures in the intake manifold, and an air-to-air intercooler lowers air temperature before it reaches the engine, resulting in a denser, cooler intake charge.
The combustion system has been completely redesigned and re-engineered to take advantage of the EcoBoost system's increased performance. The cam-driven high-pressure mechanical fuel pump operates at up to 2,200 psi - more than 50 times the norm seen in a conventional four- cylinder engine.
As demands on the turbocharged 2.0-liter EcoBoost engine are increased, the complex electronic control system responds to maintain optimal combustion, timing and injection duration.
On each stroke, seven individual jets on each fuel injector spray fuel directly into the combustion chamber, mixing with the incoming air. By bringing the fuel injector right into the combustion chamber, there's no delay from the time the fuel is injected to when it's used by the engine.
Plus, because the fuel injectors spray right into the combustion chamber, the injected gasoline evaporates and cools the air that's been inducted into the cylinder.
"Ford's direct-injection design cools the air right where it's going to be burned," said Makowski. "Engine breathing and resistance to detonation, or knocking, are all improved."
The charge cooling also allows the direct-injected turbocharged engine to run a higher compression ratio than is possible on a port fuel-injected boosted engine. The higher compression ratio equals improved fuel economy across the operating range of the engine and more horsepower per liter of displacement.
Also aiding engine breathing is Ford's advanced Ti-VCT. This technology allows precise, variable timing control of both the intake and exhaust camshafts, which control the valve opening and closing events.
Ti-VCT technology also helps further broaden the EcoBoost torque curve. Because the Ti-VCT strategy allows the intake valve to be advanced, instant power is delivered when the customer demands it at low speeds. At high speeds, the intake cam is retarded and higher airflow is available, which results in approximately a 10 percent power improvement over non-VCT engines.
The ability to vary the overlap between the intake and exhaust valves also leads to better fuel economy - approximately a 3 to 4 percent improvement from this strategy alone compared with non-VCT engines.
Since being introduced in 2009 on four vehicles - Ford Taurus SHO (standard) and Lincoln MKS full-size sedans and Ford Flex and Lincoln MKT crossovers - EcoBoost engines have been embraced by customers.
The addition of a four-cylinder EcoBoost to Ford's lineup is a strong answer to consumer demand for engines of this size. Approximately one-third of Ford's U.S. engine volume is four-cylinder, as customers focus more on fuel economy and lower emissions. EcoBoost engines help deliver performance on both fronts, cutting CO2 emissions by up to 15 percent compared with larger-displacement engines with similar power.
The 2.0-liter EcoBoost is the first engine in the EcoBoost lineup to go truly global. Ford S-MAX and Galaxy, two people-moving products on sale in Europe, also were announced with a 2.0-liter EcoBoost option. In addition, the same engine will join the powertrain lineup for the Ford Falcon on sale in Australia.
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