The new twin-turbocharged 3.5-liter EcoBoost™ V-6 engine – available this summer on the 2010 Taurus SHO – is a complex, carefully balanced machine. But developing a new engine technology of this magnitude required unprecedented collaboration with supplier partners.
The result is an engine that delivers V-8 power with V-6 fuel economy, by optimizing the additional power gained from turbochargers and combining it with the efficiency of direct fuel injection. To deliver this performance, each component required special attention to help maximize the potential of combining these existing technologies in a new approach.
That meant Ford needed to forge new bonds with its suppliers as its engineers developed the EcoBoost system. Just as the success of the engine is tied to the quality of its various components, so too is Ford’s ability to create groundbreaking solutions tied to its supply partners.
Fuel-Charging System Engineering Collaboration
The twin-turbocharged 3.5-liter EcoBoost V-6 engine’s enhanced fuel-charging system, and the fuel pipe that feeds them, are good examples of the collaboration between Ford and its suppliers – in this case Bosch. The fuel pressures in the EcoBoost’s direct-injection system can reach up to 2,150 psi, more than 35 times the norm seen in a conventional port-fuel-injected V-6, and required specific engineering to meet the required robustness as well as improved function.
Most fuel systems also are broken into subsystems such as fuel pump, fuel lines, fuel rails and injectors. But, there are significant common factors that affect the entire system performance – such as fuel flow, thermal distribution, fuel distribution, NVH and hydraulic pulsations. Those input factors require system tuning and design techniques to improve the whole system performance, which is achieved by combining the technical expertise and resources offered by the supplier and OEM.
“Our own Ford Vehicle Benchmarking Center showed that many suppliers applied a common practice design approach of ‘one size fits all’ and with little consideration as to how the subsystems could be fine-tuned for optimized function and performance,” said Joseph Basmaji, direct injection fuel system technical specialist.
For example, hydraulic pulsations – or hammering – is a common issue in all direct-injection fuel systems and can cause a range of issues, from poor fuel distribution to component durability. Knowing how to address these pulsations in each of the subsystems is critical to being able to effectively reduce the pulsations of the entire system to an acceptable level and achieve optimized performance.
The Ford and Bosch teams worked for months to develop hydraulic models and prototypes to provide the data leading to optimized orifice sizing, placement and spacing in order to tune in the hydraulic frequencies in each of the subsystems. “As a result, hydraulic pulsations to the entire system could be reduced, providing better fuel distribution for improved component durability, function, performance and reduced emissions,” Basmaji said.
Another new approach used on the EcoBoost engine is the bolting pattern for the high-pressure fuel rails. Ford’s collaboration with Bosch led to a fastening design concept that incorporates a criss-cross pattern across the rail, as opposed to brackets on one side of the rail only. This pattern reduces the moment arm on the rail as well as some of the high stresses that can result because of the tendency for the rail to lift under the 2,150 psi hydraulic pressure of the fuel.
“Close collaboration with our suppliers and sub-suppliers also helped us in the design and development of a fully automated fuel-charging assembly and rundown station at Cleveland Engine Plant. It’s the first of its kind and possibly a benchmark for the industry,” Basmaji said.
Y-Pipe Fuel Delivery System
Ford and Bosch also developed a new Y-pipe fuel delivery system, rather than a conventional multi-pipe system, to feed the fuel rails. The Y-pipe method provided several advantages in a direct injection system, including reduced pulsations, hydraulic frequency separation, improved fuel distribution and assembly improvements. The Y-pipe also fills both rail halves simultaneously, as opposed to a multi-pipe system, where one rail must fill completely before filling the other rail. This solution reduces green start times at the vehicle plant as well as vehicle start time in the field.
“Development of the Y-pipe was a first for us and a first for Bosch,” Basmaji said. The Y-pipe also provides better fuel thermal distribution, minimizing fuel distribution issues from fluid density changes. “The result is a more-precise delivery of the fuel mass required for a more-efficient fuel burn in the combustion chamber and better fuel economy,” Basmaji said. “The fuel distribution is improved bank to bank as well as injector to injector. That’s very critical and one of the major reasons our fuel-charging system runs as well as it does.”
Developing new methods of engineering and strong relationships with partners are key to Ford being able to develop world-class technologies and maintaining a leadership position with systems such as EcoBoost.
“We don’t just take technologies at face value; instead, we work with our partners to drive better technologies,” Basmaji said. “We know we have to be better than the competition and that’s what we’re out to do.”
Twin Turbochargers a New Approach for Gasoline Engines
The EcoBoost system uses two Honeywell GT15 turbochargers – one on each bank working in tandem – to harness exhaust gas to pump V-8 power out of the smaller-displacement V-6 engine. This technology – in conjunction with direct fuel injection – allows EcoBoost to punch above its size in terms of power and responsiveness. The 3.5-liter EcoBoost V-6 is the first gasoline direct-injection twin-turbocharged engine produced in North America.
Close collaboration between Ford and Honeywell created a system that met Ford’s rigorous durability and safety criteria with such refinement that the driver never notices the turbocharger operation. Sophisticated electronic controls balance boost and torque levels to give the driver the feeling of continuous torque delivery without turbo “whines” and “whooshes” that characterized some previous-generation turbocharger engines.
“One of the principles behind EcoBoost is that it isn’t intrusive,” said Keith Plagens, Turbo System Engineer. “EcoBoost delivers added power seamlessly. Using Honeywell’s GT15 turbochargers gave us the performance feel and low-end response our customers demand.”
The turbocharger system features a pressure-controlled waste gate with an internal valve set at the Honeywell factory to within 3/10ths of a psi. “That means our side-to-side balance is well controlled and, again, gives the customer seamless operation,” Plagens said.
Exhaust gas flowing through the turbocharger spins a turbine wheel at very high speed – approximately 170,000 rpm – which drives a compressor turbine on the clean-air side of the turbo. This fan effect densely packs intake air into the engine – compressed air up to 12 psi that results in increased performance. With its twin turbochargers, the EcoBoost V-6 swallows about 25 percent more air than its normally aspirated cousin, the 3.5-liter Duratec V-6.
The EcoBoost approach eliminates several customer worries from previous turbocharger applications. Designed for long-life reliability, EcoBoost’s turbochargers feature water-cooled bearing jackets. This architecture is designed to prevent oil “coking” that could occur in previous-generation turbochargers. The new design means that EcoBoost drivers don’t need to observe special operating precautions, such as idling the engine before switching it off. The turbochargers are designed for a life cycle of at least 150,000 miles or 10 years.
The 3.5-liter EcoBoost V-6 engine – the first V-6 direct-injection twin-turbocharged engine produced in North America – is one of Ford’s key initiatives to deliver significant fuel economy advancements without sacrificing the performance feel customers want. By 2013, more than 90 percent of Ford’s North American lineup will be available with EcoBoost technology – part of the company’s strategy to bring affordable fuel efficiency improvements to millions.
About Ford Motor Company
Ford Motor Company, a global automotive industry leader based in Dearborn, Mich., manufactures or distributes automobiles across six continents. With about 205,000 employees and about 90 plants worldwide, the company's automotive brands include Ford, Lincoln, Mercury and Volvo. The company provides financial services through Ford Motor Credit Company. For more information regarding Ford's products, please visit www.ford.com.