While other automakers explore hybrids and new tech in their pursuit of better fuel economy, Mazda is concentrating on refining the more than century old internal combustion engine. The automaker told Automotive News says that it expects to achieve 30% better mileage with its next generation of ICEs than the fuel economy of its relatively new line of Skyactiv engines currently being rolled out. Called Skyactive 2, the next gen gasoline and diesel engines will debut around 2020, according to Mitsuo Hitomi, who heads Mazda’s powertrain development. “If we want to dramatically improve fuel economy from here, the only route is through lean burning,” Hitomi said at briefing at Mazda’s Yokohama technical center.
Hitomi said Mazda is driven by a need to meet tougher European carbon dioxide emissions standards of 95 grams per kilometer in 2020 and 65 grams per kilometer in 2025. “The next step is the 2020 European regulations,” Hitomi said. “[Skyactiv 2] must help us with that.”
Mazda’s current gasoline Skyactiv motors, which are still propagating across the automaker’s lineup, got their improved fuel economy by by pairing direct injection with higher compression ratios, allowing a leaner fuel/air mixture.
In the second generation of Skyactiv engines Mazda will increase the gasoline engines’ compression ratio to 18:1, from a current level of 14:1, the highest currently used by a major automaker. The Skyactiv 2 gasoline engine will also use homogeneous charge compression ignition, HCCI, essentially sparkless compression ignition as used in diesel engines. HCCI engines have more complete fuel combustion and lower emissions of nitrogen oxide.
Mazda says that with HCCI the Skyactiv 2 engines will be efficient enough that the company can avoid the use of CVTs or expensive multispeed automatic transmissions.
Barriers still remain to implementing HCCI in a practical automobile engine, particularly getting the system to work well at a broad range of RPMs with a variety of commercial gasoline blends as well as controlling engine and fuel temperatures.
In November, Mazda’s new CEO Masamichi Kogai said that Mazda is pursuing a goal of refining the internal combustion engine because dramatic results can be achieved cost effectively with proven technologies. “We will base it on the internal combustion engine and that’s where we will put the emphasis,” Kogai said. “The evolution [of Skyactiv 2] will be the same degree as the first generation.
Hitomi also indicated that a Skyactiv 3 lineup is planned to meet the 2025 standards. Hitomi said that future engine will have a system that will limit the fluctuation of heat in the combustion chamber to reduce losses from exhaust and cooling making more energy available to the wheels.