Now this is a bold claim. Mazda’s executive officer in charge of powertrain development, Mitsuo Hitomi, told Automotive News that its future SkyActiv 2 engine line-up will be 30% more efficient than the existing, still-fresh SkyActiv technologies that only debuted in 2011.
There will be plenty of time to turn that claim into reality, however, as the Mazda SkyActiv 2 line-up is not scheduled to be introduced until the end of the decade. The 2020 European regulations, with its ultra-strict CO2 emissions standards (95 grams per kilometre), is the real target.
In the matter of how, Hitomi said Mazda aims to crank the petrol engine’s compression ratio up from the existing level of 14:1 (already the industry’s highest) to 18:1. That’s because the new range will make use of homogeneous charge compression ignition, or HCCI in short.
HCCI engines make do without traditional spark plugs. A higher compression ratio would compress the fuel-air mixture to such a high pressure that it ignites by itself, similar in concept to a diesel engine’s combustion cycle. This way, more complete fuel combustion and lower emissions can be achieved.
There are some complications, though. There’s an ever-present risk of engine misfire at high and low engine speeds, and the engine’s operating temperature is much higher than that of a conventional motor. Then there’s the issue of higher fuel requirements. Even the current SkyActiv engines had to be retuned (reduced compression ratio of 13:1) to run on our fuels.
Good thing is, there’s still a long way to go. Hitomi claims that the SkyActiv 2 line-up will bring as big a jump in efficiency as the original range introduced, and an even more advanced SkyActiv 3 family is already planned for 2025. Looks like the sky’s really the limit for Mazda.