As the Advanced Engine Design and Development Manager at Ford, Brett Hinds has been leading the team there that developed the "EcoBoost" engines. That's as in one part fuel economy—as in an improvement up to 20%—and one part an improvement gain—the EcoBoost V6 in the 2010 Ford Flex produces 355 hp, 35% more than the base V6 for the car, and 350 lb-ft of torque, a 41% gain. The all-aluminum engine features direct injection and twin turbochargers, the first engine in Ford's lineup with such features. And Hinds acknowledges that going forward, this architecture will be the base of more engines because compared with diesel technology, it provides performance advantages at a manufacturing price point that provides a faster payback, while providing not only fuel efficiency, but the kind of torque that one might associate with a compression-ignition engine. Or a bigger engine. And to that point, Ford engineers did a rather convincing demonstration by comparing the EcoBoost Flex crossover against a Chevrolet Tahoe in a towing demonstration north of Boulder, Colorado, where a normally aspirated engine like the 5.3-liter V8 in the Tahoe has to struggle to find air and the twin turbos find advantage (compared to the normally aspirated Ford 3.5-liter Duratec V6 used in the Flex, the EcoBoost is able to suck in about 25% more air). In addition to which, the bigger V8 provides 335 lb-ft of torque at 4,400 rpm while the Ford V6 produces 350 lb-ft of torque at from 1,500 to 5,250 rpm.
The twin turbos deployed are the result of collaborative work between Ford and Honeywell Turbo Technologies (honeywell.com/sites/ts/tt), which is providing the GT15 turbos, one turbo per bank, working in tandem. One key consideration—in addition to performance—was an assurance that the turbos would perform transparently, not only from the standpoint of modulating the boost and torque so that there aren't the "whines" or other sounds traditionally associated with turbos (realize that in operation, these turbos are running at about 170,000 rpm), but such that they would have long-lived performance without special treatment (e.g., idling the engine before shutting it off). The turbos are fitted with water-cooled bearing jackets so oil coking problems are avoided. They've been validated to operate for 150,000 miles or 10 years.
The direct injection system was developed by Ford working with Bosch (bosch.us). The fuel pressures in the system can reach up to 2.150 psi, which is about 35 times the pressure in port-injected systems. During development the system was looked at holistically rather than discretely (i.e., fuel pump, fuel lines, fuel rails, injectors) for the simple reason that the overall system performance is key, and to achieve it there are factors including fuel flow, thermal distribution, fuel distribution, NVH, and hydraulic pulsations, which are systemic in nature, not discrete. So, for example, to minimize hydraulic pulsations that can contribute to "hammering," which is not only unpleasant to hear, but can contribute to issues with fuel distribution and component durability, Ford and Bosch engineers spent considerable time performing hydraulic modeling so as to optimize the orifice sizing, placement and spacing so that the hydraulic frequencies could be tuned. In addition to which, Ford and Bosch developed a Y-pipe fuel delivery system for the fuel rails rather than the typical multipipe system. With this pipe, both rails are filled simultaneously, not sequentially. There are several benefits, including more efficient fuel burn, which results in better fuel economy. They even redesigned the bolting pattern for the fuel rails to the engine, using a crisscross pattern across the rail, rather than having brackets on a single side of a rail, thereby reducing the moment arm and stresses on the rail—remember, this is 2,150 psi of hydraulic pressure.—GSV