The larger of the two is a 1.3-liter, while the smaller engine, a 1.0-liter, was developed in collaboration with Daihatsu. What makes these two unique is that they both use the Atkinson cycle. Now, we aren't going to bore you by explaining just what this is - there's Google for that. Suffice it to say, Atkinson engines are highly efficient, but that efficiency comes by sacrificing power. That's why they're so popular in hybrids, which can offset the power losses.
This focus on fuel efficiency extends throughout the new engines, which also benefit from tweaks like a cooled exhaust gas recirculation system and a trick intake port, while the 1.3 employs Toyota's iE variant of variable valve timing. Both engines can be fitted with stop-start tech. According to Toyota, when fitted with stop-start the 1.3 should provide around a 15-percent bump while the 1.0-liter will increase economy around 30 percent, when they arrive on the road.
We're not going to lie, the non-hybrid Atkinson system is a question mark. But according to General Manager of Powertrain Planning Shouji Adachi, it shouldn't be an issue.
"There is always the challenge of lower performance in torque," Adachi-san told Automotive News. "For the new engines, we were able to resolve these issues."
We're presuming that what Adachi is referring to is Toyota's use of high compression ratios on both engines - 13.5 in the case of the 1.3L and 11.5 in the 1.0L. Using a higher compression ratio allows the engine to develop more power thanks to increased thermal efficiency. In the case of the 1.3L, max thermal efficiency is at 38 percent, which Toyota says is quite good. The 1.0L is just a smidge behind, at 37 percent.
So, power concerns momentarily swept aside, where to do we think these engines will end up? According to AN, non-hybrid, JDM compacts will be the first to use the new engines. From there, though, it's really anyone's guess where these engines and their variants will end up. Scroll on down for the short press release on the two engines, from Toyota.
Toyota City, Japan, April 10, 2014―Toyota Motor Corporation aims to further increase the environmental performance of its vehicles with a series of newly-developed, highly fuel-efficient engines that achieve outstanding thermal efficiency1. The new engines leverage combustion and loss-reduction technologies Toyota has refined in its dedicated hybrid engines, and will achieve fuel efficiency improvements of at least 10 percent2 over current vehicles. The engines will be used in models scheduled for partial redesign in the near future, and a total of 14 new engine variations will be introduced globally by 2015.
One of the engines is a 1.3-liter gasoline engine in which Toyota is employing the Atkinson cycle3―normally used in dedicated hybrid engines. Use of the Atkinson cycle provides an increased expansion ratio and reduces waste heat through a high compression ratio (13.5), resulting in superior thermal efficiency. Toyota aims to further improve the fuel efficiency of the engine by utilizing other innovations including an intake port with a new shape that generates a strong tumble flow (whereby the air-fuel mixture flows in a vertical swirl) inside the cylinder, and a cooled exhaust gas recirculation (EGR) system paired with Variable Valve Timing-intelligent Electric (VVT-iE) technology to improve combustion and reduce loss. As a result, the new engine will have a maximum thermal efficiency of 38 percent4―top-level among mass-produced engines. The new features, combined with idling stop and other functions, will lead to fuel efficiency gains of approximately 15 percent2 by comparison with current vehicles.
Meanwhile, a 1.0-liter engine jointly developed with Daihatsu Motor Co., Ltd. has achieved maximum thermal efficiency of 37 percent4 due to a similar tumble flow-generating intake port, a cooled EGR system, and a high compression ratio. Combination with the idling-stop function and various other fuel consumption reduction technologies allows vehicles to achieve a maximum fuel efficiency improvement of approximately 30 percent2 over current vehicles.