Toyota Motor Corp. surprised many last week with the announcement of its two new power plants. Both engines, which are said to improve fuel economy by 10 percent, will underpin 14 new engine variants that will be introduced around the world through 2015.
The gasoline engines—one 1.3-liter, 4-cylinder and the other 1.0-liter, 3-cylinder—are the first to be developed at Toyota’s new Powertrain Joint Development Building, a 12-story R&D facility located in Toyota City in Japan. They give a glimpse to the kind of drivetrains one could expect from the Toyota New Global Architecture (TNGA), the automaker’s revamped development plan which seeks to increase car part commonality. The first batch of cars built with TNGA will roll out next year.
The base technology of these fresh engines will be used in the development of larger engines, which will be put in premium vehicles and hybrids alike. The new engines will also serve as a basis for Toyota’s direct-injection and turbocharging engines. The upcoming 14 new engines, which will be arriving in the next two years, are expected to be used in 30 percent of the auto giant’s global nameplates.
While Toyota did not identify the vehicles that will get its two newest engines, it is speculated that the power plants will be used in non-hybrid compact cars to be sold in Japan.
One thing that makes these gasoline engines fuel efficient is the Atkinson burning cycle. The cycle, which was only used for the Japanese automaker’s hybrid vehicles in the past, is finally introduced to gasoline engines. This marks the first time the company will be applying the Atkinson cycle in engines that will not be deployed solely for gasoline-electric vehicles.
The Atkinson cycle contributes to the engine’s fuel efficiency by keeping the intake valves open amid the compression stroke. Unfortunately, it also contributes to lower power. This may not be a problem for hybrids because of the power produced by the electric motor, but it will be a major concern for non-hybrids which do not have another power source.
Toyota considered this problem during the development of the engines, and this is why the carmaker came up with a way to deliver the horsepower while still utilizing the Atkinson cycle. For instance, it increased the compression ratio: the 1.3-liter reaches a compression ratio of 13.5 while the 1.0-liter engine reaches a ratio of 11.5.
Others that allow Toyota’s engines to achieve increased fuel economy and power include intake ports that make vertical air-fuel swirl for faster combustion as well as variable valve timing that boosts combustion efficiency. The power plants also come with a cooled exhaust gas recirculation system that decreases nitrogen oxide emissions.
The 1.3-liter engine is reported to have a 38 percent thermal efficiency rate, while the rate for the 1.0-liter engine is 37 percent. These rates are better compared to the 35 percent thermal efficiency rate of the outgoing engines.
Toyota follows Japanese rivals Honda Motor Co. and Mazda Motor Corp. which have revamped their own engine lines to meet stricter fuel economy requirements.
Photo credit: toyota-global.com