Packing 123 Horsepower Into 3 Cylinders

Craig Daitch needed to fly to Los Angeles on short notice, and he had more than the usual amount of baggage.
In addition to a laptop and extra clothes, Mr. Daitch, manager for car communications at Ford Motor, was bringing an item for display at last fall’s auto show: the largest part of a new Ford engine.
Typically, that cylinder block would be crated and shipped as cargo, with loading handled by forklift drivers. But this time Mr. Daitch stuffed the engine block into his suitcase and checked it onto the flight after passing through airport security.
At 52 pounds, the cast-iron block of Ford’s new 1-liter EcoBoost engine is a bantamweight among automobile power plants. (Mr. Daitch didn’t even incur an overweight bag fee.) With the total capacity of its three cylinders equal to the volume of a large soft-drink bottle, it’s also tiny: placed upright on a desk, the block fits easily within the edges of a file folder.
The compact dimensions of 3-cylinder engines, together with fuel efficiency and reasonably good performance, have pushed Ford and a growing list of competitors — including Audi, BMW, Citroën, Mini, Peugeot and Volkswagen — to introduce a new generation of triples, as they are often called.
“Turbocharged 3s are now replacing nonturbo 4-cylinder engines, just as fours have been replacing 6s,” said Eric Fedewa, an IHS Automotive analyst who tracks powertrain trends. He explained that in the new 3-cylinder engines, the combination of a turbocharger and features like direct fuel injection and variable cam timing “effectively serves as a fourth cylinder.”
The overall effect is to transform the 3-cylinder Davids into aspiring Goliaths. Ford’s diminutive and technically sophisticated triple will be offered in the 2014 Fiesta in the United States. Its performance — 123 horsepower and 148 pound-feet of torque — is the highest power output for its displacement of any Ford production engine, the company says.
While offering the triple in the 2,600-pound Fiesta subcompact was a logical move, Ford surprised the industry by announcing it would make the engine available next year in the 3,350-pound Mondeo, the European version of the Fusion. (It is already offered in the European C-Max.)
In the five-passenger Mondeo sedan, the 1-liter triple stretches the limits of how small an engine will adequately power a vehicle. The combination works, Ford engineers say, because the EcoBoost engine produces 90 percent of its maximum torque at a relatively low 1,500 r.p.m.
Of course, small engines in larger cars are more common in Europe, where a gallon of gasoline costs up to $8 and Fiat even sells a 2-cylinder version of its 500 model. Ford aims to achieve best-in-class fuel economy, the equivalent of about 43.5 miles per gallon, when the Mondeo equipped with the 1-liter triple and a 6-speed manual transmission goes on sale, probably next year.
Ford’s success with the Mondeo could help influence similarly radical combinations across the industry, Mr. Fedewa said, even in the United States.
Worldwide, 3-cylinder engines are best known from their wide use in motorcycles since the late 1960s by BMW, Honda, Kawasaki, Suzuki and Triumph, among others. In bikes, the triples fit neatly between 2- and 4-cylinder models.
Their revered performance in the bike world contrasts with the buzzy, underwhelming triples that soured many buyers of econoboxes sold by Daihatsu, Subaru and Suzuki in the 1980s.
Indeed, as automakers downsize their engines and coax more power from fewer cylinders, they’re also challenged with making them run as smoothly and quietly as the engines they are replacing. The natural up-and-down shaking forces are more pronounced in engines with fewer cylinders.
Another problem is so-called second-order vibration, according to Joe Bakaj, Ford’s vice president for powertrain engineering, caused by the constantly changing angle of the connecting rods as the crankshaft rotates.
The trick for designers is to minimize the natural vibrations occurring at different engine speeds by achieving balance, as much as possible, among the rotating and reciprocating parts.
The task of making a triple with a high level of refinement is not simple, Mr. Bakaj said.
By Linday Brooke
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