Twin-turbo SHO V6 showcases Ford’s EcoBoost technologies

  • 17-Jul-2009 04:48 EDT
EcoBoost V6 components.jpg

Unique cylinder heads are among the components that make the new SHO V6 such a firebreather. The SHO features a cast steel crankshaft and utilizes Inconel exhaust valves. Compression ratio is 10:1.

­“We designed this engine for 100 hp/L, and we ended up with 104 hp/L—and that was after 1000 hours of sustained dyno running at peak horsepower,” said Brett Hinds, Ford’s Advanced Engine Design and Development Manager, about the 2010 Taurus SHO’s twin-turbocharged V6.

His enthusiasm increases as he recalls what went into working out the first three seconds of the fuel injection event: “Eleven engineers spent 33,000 hours analyzing 250,000 hours of CAE simulation,” Hinds explained. "And you’ll see some fundamental piston crown geometries from this program in other EcoBoost engines.”

But while hard-core engine guy Hinds gets all spooled up over such numbers, he’s equally excited about the other side of this new engine’s story—fuel consumption that matches or betters that of V8s with similar output ratings and equipped with cylinder deactivation.

Hinds should be justifiably proud of his team’s achievement. The 3.5-L SHO (super high output) EcoBoost V6 produces 365 hp (272 kW) and 350 lb·ft (475 N·m)—102 hp (76 kW) more than the base naturally aspirated Duratec 35 that it is based on. There is only a slight drop in EPA fuel economy (17/25 mpg for the SHO vs. 18/28 mpg for the standard Taurus, even though the SHO engine has to propel a vehicle that is 274 lb (124 kg) heavier mainly due to its standard Haldex viscous-type all-wheel-drive system.

Ford has begun deploying its less-is-more-and-better EcoBoost strategy as it continues to roll out various downsized, direct-injected, turbocharged gasoline V6 and inline four-cylinder engines over the next few years. By 2012 Ford will have EcoBoosted 90% of its Ford, Lincoln, and Mercury models and in the process optimized fuel efficiency without sacrificing performance.

According to Hinds, the SHO V6 is the culmination of Ford’s learnings from Volvo (boosting) and Ford Europe (direct injection). The engine is also the fruit of development collaborations with Honeywell, which supplies the twin turbochargers, and Bosch, maker of the solenoid-actuated direct-injection system capable of 2150 psi (148 bar) injection pressures at wide-open throttle.

“Both suppliers really helped us get on the ball a lot faster,” Hinds noted.

The twin 1450-cfm Honeywell turbos are designed relatively small for reduced internal inertia to minimize turbo lag. Spinning at up to 170,000 rpm and configured to generate 12 psi (83 kPa) at WOT, the turbos help deliver a virtually flat torque curve—maximum torque is available from 1500 to 5250 rpm. This allows Taurus engineers to optimize the 3.16:1 final drive ratio, used with the 6F55 six-speed automatic, for improved fuel economy.

Hinds credited great attention to electronic engine controls, cylinder head architecture, and many hours of CFD work to allow the boosting to coexist happily with a relatively high (for a turbo engine) 10:1 compression ratio. The intercooled turbo system was designed for durability balanced with cost efficiency, he added. The output impellers are aluminum and the exhaust rotors are nickel-iron.

A two-stage cooling system designed to cope with 948ºC (1740ºF) peak exhaust temperatures is based on thermo-siphoning principals similar to those Henry Ford used to cool the iconic Model T engine.

With Chief Engineer Pete Reyes’ team reducing the Taurus program’s original time to market by 12 months, Hinds’ team also had to move fast to meet their launch bogies.

“A clear commitment from Ford’s top management made this program happen fast,” he said. “Half the EcoBoost engineering team came from Research and Advanced Engineering—they took it all the way to Job One.”

One result of the rapid-fire EcoBoost program is Hinds is now cross training dyno engineers with vehicle calibrators. “We’ve already found emissions benefits from putting both disciplines together,” he said.­

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