Mazda 3 2019 neo sport (5yr)

Mazda SkyActiv-X review

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Though it seems hard to fathom for us here in Australia, Mazda is actually a small player in the global automotive market. The Japanese brand’s dominance in Australia – as the second best-selling manufacturer – is very much an anomaly on the world stage.

The point here, though, is that as a car company, Mazda’s research and development budget is not on the same scale as the likes of Toyota, Honda or Nissan. Those three Japanese manufacturers have invested, and continue to invest, heavily into electrification technologies that they, along with a plethora of European and American manufacturers, believe will be the future of the automobile. Mazda, though, thinks otherwise.

The company claims that up until at least 2040, liquid fuels will remain the dominant source of power for the automotive industry. Furthermore, according to Mazda’s managing executive and senior technical fellow in charge of technical research centre and integrated control system developments, Mitsuo Hitomi, electric vehicles are not really necessary before the elimination of all fossil-fuel or non-renewable electric power plants.

It's a bold claim. But it's a claim in line with the company's tireless work on the development of its SkyActiv-X technologies.

So, what is SkyActiv, exactly?

Before we get into the driving component, we need to explain the technology itself, and there are many ways to explain it.

The basic idea is that SkyActiv-X takes the best a diesel engine has to offer in terms of high compression ignition and added fuel efficiency, minimal energy loss and torque gains, but without the CO2 disadvantages of burning diesel fuel or the power deficit.

It’s a concept Mercedes-Benz and General Motors, amongst others, have worked on for years, but it has – seemingly – never seen the light of day, at least in passenger cars, That leaves Mazda as the first mainstream manufacturer to introduce, what it calls Spark Controlled Compression Ignition (SPCCI).

From a more technical perspective (put your nerd hat on here, folks), the areas which Mazda engineers need to control in order to manage such a feat include the compression ratio, heat ratio and transfer, combustion period and timing, as well as mechanical friction and pressure differences between internal and external components.

In order to improve the specific heat ratio, Mazda engineers had to find a leaner burn rate and decrease combustion temperatures. This meant an increased ratio of air to fuel. Compared to the current generation SkyActiv-G, there is more than twice the amount of air being used in the combustion process. In essence, the more air used in the air:fuel ratio, the leaner the burn.

The problem is, though, that as the car gets leaner in its fuel burn, there are problems with combustion stability. Using compression ignition and spark ignition allows for a leaner burn, but with a petrol engine, the viability and stability do not work in all conditions, and across the rev range.

The current range of Homogenous Charge Compression Ignition (HCCI) systems have a leaner burn, but switching between compression ignition and spark ignition is a big challenge and can lead to a misfire due to low temperatures or poor timing. Mazda, however, claims to have found a solution.

According to Mazda, its ability to control the switch from compression ignition to spark ignition is a completely self-made technology – SPCCI is a pure Mazda technology.

Mazda says it uses the spark plug as a control factor for the switch between the two modes; the solution needed to create a fireball in the chamber that expands to the necessary size whatever the spark timing.

Mazda engineers found a way to control the timing of the combustion ignition with the flame from the spark plug itself, while keeping the air-fuel mixture lean enough that little NOx is produced in the process. The company has also applied different measures to control abnormal combustion and pre-ignition.

For the same technical reasons why a diesel engine doesn’t rev very high, the spark ignition part of the SPCCI comes into effect only at higher rev ranges, or under heavy engine load. And the switch between the two compression modes is done seamlessly.

The SPCCI hardware requirements include the need for in-cylinder sensors, high-pressure fuel systems and high response air supply, which for Mazda, includes the use of a mechanical supercharger.

So what does all that technobabble actually mean in the real world? To find out, Mazda put me behind the wheel of a SkyActiv-X-powered car running the new generation SkyActiv-X platform and chassis.

The company claims SkyActiv-X engines provide the level of power and torque of a current 2.0-litre engine from an MX-5, but with the fuel efficiency of a 1.5-litre diesel unit. Sounds almost too good to be true, but that is the stated aim.

The unit I am testing is a 2.0-litre, four-cylinder SkyActiv-X petrol engine in prototype form, with which Mazda is aiming to achieve an output of around 142kW and 230Nm of torque with a real world fuel efficiency use of roughly 5L/100km.

Those are figures hard to associate with any current non-electrified, petrol engine of that size. But Mazda claims that in production form, the technology will improve fuel efficiency by up to 20 to 30 per cent over its current SkyActiv petrol engines.

My prototype vehicles are wearing the body of a current Mazda 3 but everything else is next-generation, including the chassis and platform.

Perhaps the most notable thing with the new SkyActiv-X engines is the initial feel on acceleration. There is a much higher level of response to the throttle early on, but in my prototype test cars, first gear seems to be rather short and the engine doesn't seem to want to rev as high before shifting.

Even so, it’s actually all but impossible to tell you’re driving an engine that is using SPCCI technology. There is an occasional little odd noise, what I am told is 'pinging' or 'knocking', occurring when the switch takes place from compression ignition to spark ignition as the revs increase, or as I apply light acceleration. I am assured this issue is specific to the prototype vehicles I am driving.

I took an extended drive around Mazda’s European R&D centre in Frankfurt, reaching speeds of close to 200km/h on the Autobahn. Both the manual and automatic versions feel at home in these conditions. There is very linear power and torque delivery and the SkyActiv-X power unit feels more than adequate for its intended purpose.

While it is very difficult to actually say, hand-on-heart, that I know the engine under the bonnet is using a revolutionary ignition technology that may, single-handedly, save the internal combustion engine from extinction, I genuinely did notice the changes the next-generation of SkyActiv-X platform and chassis will bring.

Firstly, the updated platform makes the current-generation Mazda 3 feel very unrefined when it comes to noise vibration and harshness (NVH). My prototype car is so quiet inside it is almost eerie. I feel compelled to make chitchat with the German Mazda engineer riding shotgun, in order to break the relative silence, even at highway speeds.

Secondly, Mazda has made use of what it calls human-centred concepts to better find the ideal state for a human inside a car.

This has led to the development of new seats the company claims better support the pelvis and upper body and help transfer the road load to the pelvis in a natural manner. According to Mazda, the dynamic balance a human has while walking can be transferred through the car into the driver for a more natural feel of motion.

The idea, in its finality, is to redesign the seat to reduce displacement of the position of the pelvis relative to the sprung mass. According to Mazda, it has improved this displacement by more than 80 per cent.

Does it feel good? Sure. Does it feel 80 per cent more ‘natural’? Impossible to tell, really.

All I can say is the seats were super supportive and very comfortable, and, having driven the cars for close to two hours, there is no fatigue or need to shift my sitting position. It feels almost sculpted to my spine.

Mazda has also utilised a multi-directional ring structure, with much stiffer metals and design, in order to improve its new chassis and platform. According to Mazda's engineers, there is now a 30 per cent reduction in input timing delay from the front to rear.

The platform as a whole has seen major modifications on how the tyres, suspension, body and seats work together to optimise the human-centred experience.

The fact of the matter is, when the next-generation of Mazda models come to market with SkyActiv-X powertrains and platforms, the average buyer who is going to test drive and buy the vehicle will probably not have the slightest clue as to what is happening under the bonnet (much like now). But, they will be absolutely delighted with the improved fuel economy, power and torque output as well as the significantly refined levels of NVH and cabin comfort.

We are very much looking forward to seeing these vehicles in production trim, but for now, I have to hand it to Mazda for not giving up on the internal combustion engine.

Some may be cynical and say the Japanese brand has no choice but to continue to invest in traditional engines, for it doesn’t have the budgets to compete with its much bigger rivals when it comes to electrification – and that may be true – but it appears that much like SkyActiv-X itself, Mazda now has the best of both worlds.

Having Toyota become a Mazda shareholder means the company can access the Japanese giant’s massive knowledge of hybrid and electric vehicles (Toyota was a shareholder in Tesla and had access to the American company’s technology as well) while continuing to bet on its belief in the internal combustion engine for the foreseeable future.

Only time will tell if the company’s efforts will be rewarded or whether governments around the world will continue down the path of eradicating the internal combustion engine, regardless of its real-world, 'well-to-wheel' emissions in comparison to electric vehicles.

For now at least, there seems to be plenty of life and innovation still left in the modern world for our much-loved, fuel-burning powertrains.

MORE: Everything Mazda


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