Mazda Skyactiv-X



Ribbed ducts poke out of the dash sending two breaths of conditioned air to no one in particular. Even its revolutionary engine, the thing we’re here to experience, is entombed in a massive, nondescript cover to mask its unseemly noises. It’s a wild, strange way to meet a very unconventional vehicle that promises diesel-like fuel economy, a wide torque band, and an exotic method for burning less gas than ever before.

It takes a few hours for Mazda’s engineers to explain the fundamental principles of operation. For more detail, read our Skyactiv-X Spark Controlled Compression Ignition explainer, but here’s a very brief overview.

Skyactiv-X marries some traditional gasoline engine characteristics with a novel form of compression ignition called SPCCI. The key for Skyactiv-X is to use very high compression in the cylinder and an extremely lean fuel-air mixture. Squeezed right to the cusp of getting hot enough to blow up all on its own (which is very hard to predict), a squirt of extra gas and a spark interject to cross that compression-ignition threshold in a controlled and predictable manner. See the animation below:

That speaks to Mazda’s philosophy in building the Skyactiv engine range in general. Mazda has avoided electrification almost entirely; what electrification it employs is either very minimal (i-eLoop regenerative braking and capacitor system) or niche (Demio EV, with its rotary range extender option).

But before you wonder why it’s so much less powerful than the new turbocharged Skyactiv-G 2.5T that’ll be out soon in the Mazda6, remember this: The Skyactiv-X engine is really intended to beat the weakling 2.0’s fuel economy numbers (28 city, 38 highway) by as much as 30 percent, while seriously exceeding its power output of 155 hp and 150 lb-ft. In short, it aims to crush the 2.0 liter’s economy with 2.5-liter power.

Likewise, unseemly vibrations haven’t been attacked with more heavy sound deadening, but rather with careful application of a damping adhesive between certain places in the unibody. The idea is to make the sounds less disagreeable rather than try to crowd them out entirely.

Depending on its cost, that will definitely get some consumers’ attention. And if fuel prices go up, it might spark a frenzy. Either way, no one will be able to ignore Mazda’s new engine.

Anthony Bunch Author

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