Toyota Introduces High-Efficiency Engines, Plans up to 14 Variants


1.3-liter VVT-iE four-cylinder

Toyota has pulled the wraps off a pair of newly developed high-efficiency gasoline engines, and has plans to develop an additional 14 global variants from their core architecture by 2015. Earmarked for use in models scheduled for partial redesigns in the near future, the first two are said to return improvements in fuel efficiency of 10 percent or better. The gains come largely from co-opting combustion and loss-reduction technologies Toyota garnered in the development of powerplants engineered specifically for use in hybrid vehicles.

The larger of the two is a 1.3-liter Atkinson-cycle four-cylinder that employs a 13.5:1 compression ratio. In addition to the use of the Atkinson cycle, which provides for greater thermal efficiency, the intake port is shaped to generate a strong tumble flow, which encourages the air-fuel mixture to enter the combustion chamber in an efficient vertical swirl pattern. Additionally, a cooled EGR system is paired with Toyota’s Variable Valve Timing-intelligent Electric (VVT-iE) technology to improve combustion. Toyota claims the measures will provide a maximum thermal efficiency of 38 percent, which translates—when combined with stop-start and other measures—into fuel-efficiency gains of 15 percent compared to current vehicles.Tumble

The second engine—developed in conjunction with Daihatsu Motor Co. Ltd—is a 1.0-liter unit that posts even better gains in efficiency, despite eschewing the Atkinson-cycle treatment. To get there, it uses a similarly optimized intake port, a cooled EGR system, and an as-of-yet unspecified “high” compression ratio. Combined with stop-start, the measures help the tiny 1.0-liter return a claimed 30-percent improvement in fuel efficiency compared to that of current vehicles.

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Daihatsu–partnered 1.0-liter gas engine

Toyota, which has occasionally been slow to adopt cutting-edge technologies for its lower-priced vehicles, seems to be confident using several technologies with minimal gains for a common overall goal. This approach could pay off in markets where low operating costs are valued, and where costs put hybrid powertrains out of reach of the average consumer. Curiously, this announcement comes on the heels of the news that the next-generation Toyota Yaris—which is assembled by Mazda—will likely use a Skyactiv engine. Either way, we love these tiny, tech-packed engines, so the more the merrier. On the other end of the product scale, the powerful 5.0-liter V-8 found in the 2015 Lexus RC-F will also make use of advanced technologies in the name of efficiency, employing all-electric cam phasing that allows the engine to go in and out of Atkinson-cycle operation as needed to save fuel—a first that we know of in a production engine.

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