TOKYO -- Toyota Motor Corp. is stepping up a global engine upgrade of 14 high-efficiency powerplants through 2015 with the deployment of a new downsized turbo unit.
The debuts of fuel-sipping but more-powerful engines began last year. By year end, the rollout will include 14 improved engines covering about 30 percent of Toyota's global nameplates, including such powerplants as the 2.0-liter turbocharged engine mounted in the Lexus NX crossover, the automaker said.
The latest example is a newly developed 1.2-liter direct-injection turbocharged engine for the Japan-market Toyota Auris small car, unveiled last week, following the debut of a new 1.5-liter naturally aspirated engine for the Corolla.
The suite of engines, which deliver at least 10 percent better fuel economy than existing ones, is a key part of Toyota's push to meet increasingly stringent emissions standards.
The world's largest automaker had prioritized gasoline-electric hybrid drivetrains over traditional internal combustion systems. But Toyota now is revamping base engines across the lineup. The new technologies draw on direct injection, turbocharging, high compression ratios and lean-burning Atkinson-cycle combustion.
Eight of the 14 new engines have been released. At least one of the upcoming engines will achieve a thermal efficiency rate of 40 percent, said Tetsu Yamada, general manager of engine design at Toyota's Unit Center powertrain development division.
The 1.2-liter turbo delivers thermal efficiency of 36 percent, compared with traditional turbo rates of between 30 and 35 percent. The new 1.5-liter direct-injection engine gets 38 percent. The ultraefficient engine on the Toyota Prius hybrid, by contrast, achieves thermal efficiency of 37 percent.
Thermal efficiency is a measure of how much engine power is lost through heat; a higher rate is better.
Engineers said the new 1.2-liter turbo will achieve better fuel economy than the 1.8-liter engine also offered in the Auris while delivering more powerful low-end torque.
The Japan-made Auris hatchback will arrive in the U.S. in September as the Scion iM. But the U.S. version will get only the 1.8-liter engine. Shinichi Yasui, executive chief engineer for Corolla-class vehicles, said Toyota is still weighing U.S. demand for downsized turbos. Americans, he said, tend to prefer larger displacement, naturally aspirated engines.
Toyota's new powerplants come as rivals such as Honda Motor Co. and Mazda Motor Corp. overhaul their own engine lineups.
Honda's line of Earth Dreams engines taps direct-injection technology and turbocharging. Mazda's updated Skyactiv engines pair fuel injection with ultrahigh combustion ratios.