The history of engine improvements in the U.S. has tended primarily in one direction: raw horsepower. Engines have gotten bigger and more powerful over time—and that's certainly what automakers have used as a key selling point. But U.S. automaker Ford has decided to take turbocharging and direct fuel injection in another direction: fuel efficiency.

Yesterday, Ford began production of what it's calling the EcoBoost engine: a new gasoline motor that employs turbocharging, direct fuel injection, variable timing in the valves that control fuel and exhaust flow to make a smaller, lighter six-cylinder engine perform like an eight-cylinder engine.* When these technologies are combined, "you can now significantly downsize the engine," says mechanical engineer Dan Kapp, Ford's director for power train research. "The fuel efficiency comes from a much smaller displacement engine providing equal or, in most cases, superior performance to the engine you're replacing."

In essence, the new engine works by using the turbocharging to deliver more air to the fuel burning chamber, variable valve timing to fully flush exhaust gas after combustion in the chamber and then direct injection to overcome any knocking issues.

The company estimates the new engines—which will begin appearing in the Lincoln MKS and MKZ and the Ford Flex and Taurus this summer—can deliver at least 10 percent more miles-per-gallon and therefore reduced emissions of carbon dioxide. By 2013, the company plans to produce 1.3 million vehicles with EcoBoost engines in them, including 90 percent of all Ford vehicles sold in the U.S.

Of course, such cars will be more expensive than current models, though Kapp declined to specify a price tag, saying only that fuel savings could pay for it "on the order of two years or less" at today's fuel prices. That’s compared to much longer payback times for diesels or hybrids (which Ford is also producing).

Ultimately, the EcoBoost engine will also have to cope with alternative fuels, and Ford plans in the longer-term future to move more towards hybrids and electric vehicles. But for the next decade or so, Ford will be relying on these engines to meet some of the new fuel efficiency targets announced this week and reduce pollution.

"What Ford is doing uniquely here is leveraging [EcoBoost] to deliver fuel efficiency through aggressive downsizing [of the engine] as opposed to the performance type approach," Kapp says. But it remains to be seen whether a car company that has spent years and millions of advertising dollars touting the horsepower that can be gained from such improvements (at the expense of fuel efficiency) can convince customers to change direction too.

Image 1: Lincoln MKZ engine. Copyright 2009—Ford Motor Company and Wieck Photo Database

Image 2: May 19, 2009—Production of Ford's EcoBoost engine begins at Cleveland Engine Plant No. 1. Copyright 2009—Ford Motor Company and Wieck Photo Database

*Correction(5/21/09): Due to an error, this sentence was modified after the original posting.