Gas Prices Drive Interest in Direct-injection Engines
By Jim Henry
Posted Sep. 2, 2008, at 1 p.m.
The high price of gasoline in the United States is motivating domestic and import-brand automakers to introduce newly developed, fuel-efficient, direct-injection gasoline engines in the U.S. market over the next few years.
"You're seeing diesel engines starting to look more like gasoline engines, and gasoline engines starting to look more like diesel engines, using many of the same technologies [including] direct injection, high compression and turbocharging. It's all driven by fuel economy," said Brett Hinds, Ford Motor Co. advanced engine design manager.
Both direct-injection gasoline engines and the similar in concept common-rail engines, which earlier revolutionized diesel engines, employ an extremely high-pressure spray of fuel, directly into the engine's combustion chamber. To put the changes into context, consider that the pressure is measured in pounds per square inch (psi) and Hinds notes that a typical engine with older-generation port fuel injection may deliver fuel at 100 psi; the newer direct-injection gasoline systems, at 2,000 psi; and common-rail diesel as high as 20,000 psi.
The benefits are more efficient burning, faster warm-up and less waste. The computer-controlled, direct-injection systems spray the fuel so quickly that the same cylinder may get several jets of fuel within the same stroke of the piston. The correct air-fuel mix, the precise shape of the "cone" of burning fuel and the position of the spark are also important.
Key customer benefits are better mileage, more power and less air-polluting emissions.
Ford calls its direct-injection gasoline engines "EcoBoost." These engines use direct-injection with turbocharging, which uses a turbine compressor powered by the car's own engine exhaust gases to increase the amount of air entering the engine.
Combined, direct injection plus turbocharging produces substantially more power and better mileage at the same time, Hinds said. The net effect of direct injection plus turbocharging is a V-6 engine with the fuel economy of a six-cylinder, but the power of a V-8. Similarly, you can have an inline, four-cylinder engine with the fuel economy of a four, and the power of a V-6, according to Ford.
Ford plans to ramp up the availability of EcoBoost V-6 engines in the United States starting next year, and four-cylinder engines starting in 2010. By 2012, Ford intends to offer EcoBoost engines on 80 percent of its U.S. lineup.
Others makes and models using gas saving and performance boosting technologies:
- General Motors already offers a 2.0-liter direct-injection four-cylinder gasoline engine in its Saturn Sky and Pontiac Solstice models. The turbocharged engine produces 260 hp, which is a lot for a small four-cylinder, and a respectable, EPA-estimated 28 mpg in highway driving.
- Porsche Cars North America added non-turbocharged, direct-injection gasoline engines to its Cayenne SUV last year for the 2008 model year, and the company will introduce similar engines for the iconic 911 sports car this fall. The 2008 Porsche Cayenne got a bigger V-6 engine, at 3.6 liters, that produces 290 hp, at an EPA-estimated 18 mpg city/22 mpg highway. It replaced a 3.2-liter V-6 that got 247 hp, at 15 mpg city/20 mpg highway.
- Toyota Motor Co. also offers a version of direct injection gasoline engines on some Lexus models with V-6 and V-8 engines.
A similar technological revolution took place in Europe starting in the late 1990s with common-rail diesel engines, which employ even higher injection pressures than direct-injection gasoline engines. For now, Porsche, Ford and others are planning to export its direct-injection gasoline system to the U.S. market.
Bio: Jim Henry is a veteran freelance automotive writer. He was a one-man bureau in New York City for Detroit-based Automotive News for many years. He is also a past president and a board member of the International Motor Press Association.
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