|The 3.5-liter EcoBoost V-6 engine. Click to enlarge.|
Ford’s first EcoBoost engine, a 3.5-liter direct-injection, twin-turbocharged V-6, made its debut in the 2010 Lincoln MKS at the North American International Auto Show in Detroit. The 3.5L EcoBoost engine delivers 355 hp (265 kW) and 350 lb-ft (475 Nm) of torque across a broad rpm range, giving the Lincoln MKS the power of a normally aspirated 4.6-liter V-8. The engine will also be applied in the 2010 Ford Flex and Lincoln MKT crossover vehicles.
Ford also used the Detroit show to unveil a Lincoln C (C-size) concept car powered by a 1.6-liter, four-cylinder EcoBoost engine mated to a dual-clutch Powershift Transmission. With that powertrain, the Lincoln C achieves a projected 43 mpg on the highway, while offering up an estimated 180 hp (134 kW) and 180 lb-ft (244 Nm) of torque. That’s a nearly 25% fuel-economy improvement over the C-car sized Ford Focus equipped with a 2.0-liter naturally aspirated engine.
3.6L V-6 EcoBoost. Ford expects the 3.5L EcoBoost V-6 to attain fuel economy numbers of 16 mpg city and 25 mpg highway based on preliminary testing of the all-wheel-drive 2010 Lincoln MKS. The new 3.5-liter engine is the first in a series of EcoBoost engines coming from Ford as part of a strategy for wider deployment of fuel efficiency improvements. By 2013, more than 90% of Ford’s North American lineup will be available with EcoBoost technology.
The twin parallel turbochargers are water-cooled and operate simultaneously—one for the left bank of the engine, the other for the right. The high-pressure fuel pump operates up to 2,175 psi (150 bar, 15 MPa)—more than 35 times the norm seen in a conventional V-6 engine. The high-pressure pump is a cam-driven mechanical pump with a single piston and an electronic valve that controls how much fuel is routed into the fuel rails to the injectors.
As demands on the twin-turbocharged 3.5-liter EcoBoost V-6 engine are increased, the control system responds to maintain optimal combustion, timing and injection duration. On each stroke, six individual jets spray fuel directly into the combustion chamber, mixing with the incoming air. The fuel injectors are located on the side of the combustion chamber. The spray pattern for the fuel was optimized after extensive computer modeling work, with the angle of how the fuel is sprayed key to the process.
The simultaneous turbocharger operation paired with the direct-injection system help to virtually eliminate turbo lag. Ford says its dual-turbocharger setup has several advantages over previous turbocharging systems, including:
The turbochargers are smaller, resulting in more-compact exhaust manifolds, which don’t generate as much heat.
Turbochargers are packaged adjacent to the cylinder block and have improved mounting providing NVH (noise, vibration, harshness) improvements.
The dual turbochargers spool up quicker, allowing the 3.5-liter EcoBoost V-6 engine to reach peak torque faster. The turbochargers spin at approximately 170,000 rpm.
Turbocharger “whoosh” is mitigated by electronically controlled anti-surge valves, which proactively relieve the boost in the intake, which can range up to 12 PSI. Careful software calibrations manage the pressures in the intake manifold.
During development, start-up tests using a wide variety of fuel were made in conditions ranging from -40 to +110 °F. Altitude testing up to 12,000 feet in Colorado also was performed.
The direct-injection fuel system allows us some real opportunities in terms of optimizing cold start for both emissions and robustness. We have multiple injections for each combustion event, and we can essentially tune where those injections should take place to deliver the strongest start possible with the lowest emissions.— Brett Hinds, EcoBoost design manager.
Mated to the 3.5-liter EcoBoost V-6 engine in the Lincoln MKS is the 6-speed 6F-55 SelectShift automatic transmission, which is dedicated to the twin-turbocharger engine. The 6F-55 transmission was developed from the 6F-50 transmission to specifically respond to the increased torque demands of the EcoBoost V-6 engine. Upgrades were made to the transmission’s friction material in response to the higher shift energies, and a new torque converter has been optimized for performance and fuel economy.
Additionally, the 6F-55 transmission operates more efficiently. The transmission team was able to reduce the fluid level in the transmission, which in turn reduced weight and drag torque on the system. Upgrades to the transmission’s thermal valve mean the system warms up quicker, reducing gear-spin losses.
1.6L EcoBoost. The Lincoln C concept’s 1.6-liter engine shows the common attributes of Ford’s EcoBoost strategy, leveraging a combination of direct fuel injection technology and turbocharging to deliver significantly improved fuel economy and torque versus a larger displacement engine, while reducing emissions up to 15%.
The 1.6-liter EcoBoost engine features turbocharging and a central-injector direct injection system. Using a central injector instead of a side-injector system provides improved fuel-air mixture preparation, helping to further reduce fuel consumption and lower emissions. A central injector-based system also provides the most flexible foundation for future fuel-saving technologies, according to Ford.
We know that a central injection system is a prerequisite for future global fuel economy upgrades such as stratified lean operation, homogeneous charge compression ignition or HCCI, and premium injection system technology if the market demands. It’s a value solution that gives us the ability to answer market trends quickly and provide broad market coverage, a key component of the EcoBoost strategy to deliver an affordable, fuel-efficient engine technology at high volumes.—Martin Wirth, a Ford Direct Injection Gasoline Systems and Combustion technical specialist
When compared to a standard 2.0-liter naturally aspirated engine, the 1.6-liter EcoBoost engine can deliver up to a 10% gain in fuel economy simply on the merits of the engine downsizing and boosting as well as common powertrain systems such as twin independent variable camshaft timing (TI-VCT).
TI-VCT varies the phase of the intake and exhaust cams independently for improved airflow through the engine, which delivers more torque while reducing average fuel consumption by up to 5%.
Assisted Direct Start. The 1.6-liter EcoBoost engine also features other fuel-saving powertrain technologies such as Assisted Direct Start (start-stop), which contributes to an additional 3% gain in fuel efficiency. Assisted Direct Start automatically shuts down the engine when the vehicle is at idle and automatically restarts the engine when the brake is released or gas pedal is engaged, improving fuel economy by saving idle fuel consumption.
When a vehicle comes to a stop, the electronic control unit immediately synchronizes the engine’s systems for restart. Once the brake pedal is released or the gas pedal is engaged, a short starter engagement triggers the direct fuel injection system to fill the cylinders with fuel, initiate combustion and start the engine, producing the no-hesitation vehicle launch. An advanced battery management system converts braking energy into electricity and stores it to keep electrical systems operating while the engine is not running.
This advanced system provides consistent start behavior of the stopped or stopping engine that is smooth, quiet and seamless to the customer, requiring no changes in driver behavior.
Incorporating such stop/start technology in EcoBoost system is a natural next step that should happen fairly quickly, according to Barb Samardzich, Ford Vice President of Powertrain Engineering.
Powershift Transmission. Compared to traditional automatic four-speed transmissions, the dual-clutch six-speed PowerShift transmission can help reduce fuel consumption by up to 9% depending on the application. PowerShift, for example, contributes to an estimated 8% uptick in Lincoln C’s fuel efficiency when compared to the current Focus.
he Lincoln C application of PowerShift helps illustrate the competitive advantage this transmission will offer to Ford in the global small car markets. It’s a new-to-segment technology that’s an improvement over today’s automatic transmissions in terms of fuel economy while providing customers a more connected feel between the pedal and the vehicle’s acceleration.—Jack Dorigo, North America Powertrain Planning manager
The lean curb weight of the Lincoln C enables a dry-clutch derivative of Ford’s PowerShift transmission for added efficiency and durability. A dry clutch transmits power and torque through manual transmission clutch facings, while most automatic transmissions utilize wet clutch plates submerged in oil. As a result, the dry-clutch PowerShift transmission does not require an oil pump or torque converter, providing superior mechanical efficiency.