Toyota unveils new high-efficiency gasoline engine family
Leveraging knowledge gained from its hybrid program, Toyota has developed a new family of super-efficient gasoline engines destined to spawn 14 different variations during the course of the next two years. Capable of delivering at least 10 percent better fuel economy than current equivalent counterparts, the first of these new engines will have 1.0-liter and 1.3-liter displacements. Although their initial use will be confined to several domestic-market Toyota vehicles, the automaker has confirmed plans for a subsequent global roll out.
The new Toyota 1.3-liter engine -- which features Variable Valve Timing-intelligent Electric (VVT-iE) technology - incorporates several tech tricks to achieve its efficiency gains. Most familiar is the use of Atkinson cycle timing that Toyota has previously used only on its hybrid vehicles. This alternative take on conventional timing helps enhance overall thermal efficiency - a fundamental goal of the program - while reducing pumping losses. However, going the Atkinson route does impact total power output. To counter that downside, the engine has a higher compression ratio (13.5:1), a new intake port design that promotes quicker, more complete burning of the air/fuel mix and a trick exhaust manifold that enhances the scavenging process to more fully purge the cylinder after combustion has occurred.
While the 1.0-liter engine that was co-developed with Daihatsu is a non-Atkinson cycle design and has a lower 11.5:1 compression ratio, it does share the same new port configuration, numerous redesigned components that help trim internal friction losses and a NOx-reducing cooled EGR (exhaust gas recirculation) system. These new power plants are fully compatible with conventional and hybrid applications which further enhances their potential. And Toyota says that when coupled with a supplemental start/stop system, relative efficiency gains should exceed 15 percent on the new 1.3-liter and reach nearly 30 percent on the 1.0-liter.
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