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Skyactiv-X: the internal combustion engine evolved

Mazda’s never been a company that follows trend. It doesn’t set them either but by doing things their way, they’ve managed to out-fox the entire automobile industry, or nearly.

Mazda SkyActiv-X

In order to reach their once lofty fuel efficiency goals, Mazda’s done the unthinkable: they’ve not relied on electrification, at least for now. They took the long road to efficiency be rethinking the internal combustion engine and extracting its maximum potential. While they’ve not yet reached that mark, they’ve ever been closer.

As the car company with the most fuel-efficient new car fleet for the last five years, Mazda’s clearly done something right. The majority of other car makers took a quicker route to increasing fuel economy: shrinking engine sizes, slapping on turbocharger, adding many more gears or taking them all out (CVT.) The result is tangible but no better than using a Band-Aid to heal a massive gash.

Mazda’s plan is to reduce 2010 emission levels by 50% by 2030 and by 90% by 2050. Although they will eventually achieve these goals via electrification, they’ll have optimized the Internal Combustion Engine (ICE) which will remain a key player in the equation for some years to come.

What have they done? It’s simple really, and really not that simple at the same time. For the next generation of their well-known and acclaimed series of SkyActiv technologies, they’ve revised chassis, suspension tuning, aerodynamics, NVH control and active safety systems on what will be their 7th generation of products.

The most significant upgrades are found with the engine itself and is referred to as SkyActiv-X. The direct explanation reads as follows: The SkyActiv-X engine combines both gasoline and diesel engine technologies for ideal fuel efficiency, power and performance. The compression ratio has risen, which increases torque. The engine features both HCCI (Homogeneous Charge Compression Ignition) and SPCCI (Spark Controlled Compression Ignition) in order to maintain a lean fuel mixture and keep operating conditions optimized. Essentially, it comes down to less fuel, equal or more power, better throttle response and all the driving pleasure we’ve come to expect from Mazda.

For those desiring a few more details, the reality is that there are many other factors that come into play. Mazda engineers have devised a way to keep combustion gases cooler, increase combustion speeds, all the while using a lean compression-ignition mixture (where there’s more oxygen than fuel) which kills the possibility of wasted fuel. The list of positive and negative scenarios is long but with spark control, they can control the combustion when and as needed. They’ve even created a slightly less lean area in the center of the chamber by swirling air into the combustion chamber and injecting a little more fuel in the eye of the swirl to provoke ignition. It’s all extremely interesting yet murderously complex.

We did get the opportunity to drive some test mules, or prototypes. These cars consisted in the next generation SkyActiv chassis with a current Mazda3 body on top. This platform featured the revised suspension mounting points, re-tuned bushings and more. It was difficult, on the very brief drive, to not solely concentrate on the powertrain.

In a nutshell, the 2.0-litre 4-cylinder engine failed to get me excited. Yes, the approximate 170 lb.-ft. of torque was lovely, at times, but this was marred by lag-y uneven throttle response especially with the manual transmission. I later found out that there were issues with these cars, so I won’t judge them too harshly.

The automatic-equipped prototypes fared far better. Throttle response was linear, as was power delivery. Perhaps I was expecting a torquier high-revving affair, in other words, more performance. Our drive did not provide us with any fuel consumption information although we were able to keep track of the engine’s various combustion modes. The automatic permitted “extra-lean” combustion to occur far more often than with the manual. As expected, it will provide better fuel consumption numbers over the manual.

The drive portion of the event was not conclusive enough for me to properly evaluate the driving experience. On paper however, the technology is immensely promising. The end results are an expected 30% bump in torque and a 20% improvement in fuel economy over the current SkyActiv-G engines.

Mazda’s once again demonstrated that they are an engineering company first and foremost, and that they still love to drive. I very much look forward to driving the final product.

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