Toyota announced on Friday that it has been working on two new small-displacement engines, which will soon be found in vehicles around the world. They come in both 1.0 liter and 1.3 liter flavors, are naturally aspirated, and interestingly, do not feature direct injection — a popular trait found in today’s engines. However, Toyota says the new units “achieve outstanding thermal efficiency and fuel efficiency improvements of at least 10 percent,” so the engineers obviously did something right.
The first engine is a 1.3 liter gasoline engine, which runs on the Atkinson cycle that’s normally used in dedicated hybrid vehicles, Toyota explains. It achieves a maximum thermal efficiency of 38 percent, on the top-level among mass-produced engines, the company added. In an Atkinson cycle engine, the power and exhaust strokes are longer than the intake and compression strokes, making the engine more efficient, though to the detriment of power — making it ideal for hybrids, where the electric motor can offset the power loss.
The second is a 1.0 liter gasoline engine, jointly developed with Daihatsu Motor Co., that has achieved maximum thermal efficiency of 37 percent.
By next year, Toyota says that fourteen different variations of the two engines will be available globally. This will undoubtably include a new set of hybrid vehicles, and it’s also likely that Toyota will slip them into its super compact offerings, like the Scion iQ (the Toyota iQ everywhere else) or the Toyota Yaris. All told, the units will be applicable to about 30 percent of Toyota’s global range.
Toyota is also planning on bringing its Atkinson cycle engines to non-hybrids, too, despite the lower power numbers. “There is always the challenge of lower performance in torque,” Shouji Adachi, project general manager of powertrain planning, told Automotive News. “For the new engines, we were able to resolve these issues.”
Toyota likely upped the compression ratios to achieve the greater thermal ratings, Autoblog pointed out. The 1.3 liter uses 13.5, and the 1.0 liter uses 11.5. “Using a higher compression ratio allows the engine to develop more power thanks to increased thermal efficiency,” Autoblog explains.
Further, the new engines — when equipped with Stop-Start technology — should be able to manage a 15 percent fuel economy gain over current vehicles for the 1.3 liter, and a 30 percent gain for the 1.0 liter.