X-gen Mazda engines due 2019

Mazda has beaten premium brands like Mercedes-Benz and the orld’s largest car-makers to the ‘holy grail’ of combustion technology – compression ignition petrol engines.

And the new mills, which promise turbo-diesel torque and economy, ultra-low emissions and the refinement and responsiveness of high-performance petrol engines, are coming Down Under.

The technology is dubbed SKYACTIV-X and was recently officially announced to the automotive world. Its arrival effectively crowns Mazda as the first to productionise petrol compression ignition – a process via which engines can run ultra-lean fuel-air mixtures which are ignited by the compression process, without the need for a spark plug.

The label SKYACTIV-X refers to the engines’ ability to combine the “desirable DNA of both gasoline [petrol] and diesel engines,” Mazda’s global powertrain and vehicle development chief, Ichiro Hirose, told motoring.com.au at the marque’s Global Tech Forum in Germany last week.

“X means cross – it delivers the very best of both [technologies],” he explained.

Homogenous benefits
The benefits of what boffins call Homogenous Charge Compression Ignition (HCCI) are extra bang for each gram of petrol used (in terms of extra torque and power), drastically improved fuel economy and ultra-low emissions.

HCCI is seen as the next big step forward in increasing the efficiency of internal combustion engines and has been an area of significant R&D investment.

Although other manufacturers have test run petrol HCCI engines, they have encountered challenges in real-world applications, as combustion is usually only achievable over a narrow rpm and engine load range.

Ironically, the technology Mazda has used to achieve true production application for the so-called HCCI ‘sparkless’ engines is a sparkplug!

Indeed, via patented and ultra-fine control of fuelling, ignition timing and around nine other engine and environmental parameters, Mazda’s Spark Controlled Compression Ignition (SPCCI) uses a spark-initiated ‘fireball’ within the combustion chamber to further build combustion pressures and initiate compression ignition across a wide range of conditions -- with all the attendant benefits.Mazda claims that SPCCI enables the new petrol SKYACTIV-X engines to operate in compression ignition modes for all but a fraction of their normal cycles.

The key exceptions are cold starting and very high-load, high-rpm conditions. The latter, at least, is just a fraction of the likely duty cycle in normal passenger car applications.

In our test drives of both manual and automatic SKYACTIV-X Mazda3 mules at last week’s tech forum hosted at Mazda’s Oberusel research centre near Frankfurt, we achieved better than 85 per cent SPCCI running.

Mazda’s simulations placed fuel economy benefits at between 12 and 15 per cent compared to the already impressive SKYACTIV-G petrol.

Mazda is not quoting power, torque or consumption figures yet for the new SKYACTIV-X powertrains, but suggests that substantial low-rpm torque increases and better engine response will significantly improve in-gear acceleration figures.

This too was confirmed by our test drive. Indeed, there were marked improvements in drivability and performance compared to the conventional 2.0-litre Mazda3 engine with which we’re well acquainted.

Fuel economy of the finished product will rival or better existing SKYACTIV-D turbo-diesel models, says Mazda’s global R&D boss (and potential future corporation president), Kiyoshi Fujiwara (pictured).

SPCCI, Mazda claims, also increases the ‘sweet spot’ for fuel economy, delivering an opportunity to move away from the extremely high gearing that afflicts many competitors’ cars in search of economy.

The hard parts
Hardware changes to the new-generation engines include a supercharger. Like its performance counterpart, the blower’s role in the SKYACTIV-X engine is to ‘over-pressure’ the cylinders.

In contrast, its operation is not a precursor for copious amounts of fuel to be ‘poured’ into the engine. Mazda boffins religiously referred to the hardware as an “air-supply unit”, conscious of the fact that supercharging and economy are rarely used in the same sentence.

Other hardware changes include new in-cylinder sensors and, according to Hirose, “drastic improvements in computing power”.

The new SKYACTIV-X’s control units monitor combustion and compare it to an ideal combustion model to adjust parameters “cycle by cycle”, a process the engine development boss says would have been impossible just a few years ago.

No data was supplied on the increase in engine mass nor, as noted above, formal outputs.

More of this will be shared as the first SKYACTIV-X engined vehicle, the next-generation Mazda3, is rolled out in 2018. The first glimpse of the car is expected at next month’s Tokyo motor show.

The new car features the next generation of SKYACTIV platform, which was also on display at the Tech Forum.

Long-term relevance
As part of the forum, Mazda confirmed its powertrain rollout through to its 100th anniversary in 2020 and beyond.

The company says it is committed to debuting a production EV with the option of a rotary range-extending system in 2019. The company’s first mild hybrids are confirmed on the same timeline, with a plug-in hybrid on the books for “2021 and beyond”.Within this framework, Mazda says SPCCI is the technology that will keep internal combustion engines relevant beyond 2035. At that time, Mazda estimates, more than 84 per cent of the vehicles it sells will still feature an engine of some type.

Accordingly, Fujiwara says SKYACTIV-X is an important step in the company’s continuing ‘building block’ development strategy.

SPCCI SKYACTIV-X engines will be sold alongside SKYACTIV-G petrol and SKYACTIV-D turbo-diesel engine and will be incorporated in future models in conventional, mild-hybrid and plug-in hybrid guises, the R&D boss says.

Hirose also confirmed SKYACTIV-X technology is compatible with idle-stop, regenerative braking and turbocharging.

Diesel to benefit too
Global R&D boss Fujiwara was at pains to point out that SKYACTIV-X would not derail major improvements in both the SKYACTIV-G and D powertrains.

“SKYACTIV-G is the core of the [Mazda] business,” he told motoring.com.au.

SKYACTIV-D, he says, will be subject to a step change in performance when the next generation is rolled out in 2020. He characterised the technology for the next-gen diesel as “equally revolutionary”.

“Today I cannot say anything. Currently the [new generation] diesel engine is a little bit hidden [secret],” Fujiwara stated, although admitting the next-gen diesel will offer efficiencies beyond SKYACTIV-X.

“SKYACTIV-X is beyond [current] SKYACTIV-D… Currently the diesel engine is trying too hard to get beyond SKYACTIV-X. That kind of competition in our company is the best way to develop [the new generation engine].

The global R&D boss also said he believed the technology delivered in the next-gen diesel would slow down or arrest moves to ban diesels.

Mazda’s turbo-diesel technology is one of the few not under an emission-related ‘cloud’ in the wake of #Dieselgate.

Indeed, SKYACTIV-X and Mazda’s next-gen SKYACTIV-D continue to fly the face of this and the global turbo/downsizing trend. The ‘mainstream’ X powerplant also remains at a full 2.0 litres in displacement.

Australian consumers will likely be one of the first to gain access to the new technology via the next-gen Mazda3. It’s unlikely to replace conventional petrol or turbo-diesel variants, instead, SKYACTIV-X will be offered as an additional engine variant.

Marketplaces with more stringent emission levels such as Europe will be key targets for Mazda’s SPCCI technology.

Another plus for potential Aussie buyers is that, unlike some engine tech, SKYACTIV-X is not reliant on high-quality fuel to meet performance targets. Indeed, lower octane fuels can be an advantage, Mazda’s experts opined.

Extra cost for the new petrol engines is likely to be aligned with “turbo-diesel premiums”, Mazda insiders told motoring.com.au.