The compression ignition petrol engine Mazda is touting for its next-generation of cars is almost here, due to make its debut in the fourth-generation 3 hatch and sedan (BP). As that horizon looms, the Hiroshima-based automaker has peeled back more of its technical specification.
True innovations in internal combustion come along quite rarely, instead taking far more iterative steps toward greater efficiency and improved performance, often simultaneously. However, Mazda’s new SkyActiv-X family of engines can be counted as a significant step forward. That is, if it lives up to its claims.
By operating its combustion process by way of diesel-like compression ignition, SkyActiv-X negates the need for spark plugs in theory. In practice, however, each cylinder in the four-pot 2.0-cylinder unit does still have one despite not being needed all the time.
For many months now, we could only speculate at the real world performance such a combustion system would yield, but now Mazda has released official information for the incoming Mazda3 for the European market equipped with the new engine.
The 2.0-litre SkyActiv-X with a manual transmission is claimed to produce a maximum of 177 horsepower (132kW) at 6,000rpm and 224Nm at 3,000rpm. When compared to the current crop of SkyActiv-G engines of identical capacity and format (114kW/200Nm), the difference in raw numbers are modest.
In terms of fuel consumption and exhaust emissions under the older NEDC (New European Driving Cycle) standard, the same SkyActiv-X is claimed to return the equivalent of 5.3-litres/100km or 6.4-litres/100km if an automatic transmission is fitted. With 16-inch wheels all around, as little as 96g/km is emitted.
Under normal driving, the engine’s computers will make millisecond determinations as to whether to invoke the spark plug present in each cylinder to aid the ignition. Given ideal fuel quality and conditions, the engine will rely entirely on in-cylinder pressure to ignite the air and fuel mixture.
When in its most frugal, the engine is able to maintain spark-less combustion at a much leaner mixture of fuel to air to bring thermal efficiency to a level not previously possible with conventional combustion methods. Also, to ensure a consistent supply and pressure of air, Mazda has also installed the SkyActiv-X with a low-capacity supercharger.
Aiding the Mazda3 further, each car with this new engine will also boast a 24V electrical architecture to support mild hybrid features such as kinetic energy recovery during braking upon which can be used to power a discrete electric motor that, among other things, can spool the supercharger.
We will still have to wait and see how Mazda’s new engine technology translate into real-world improvements and if their promises of better acceleration and response are met. Most importantly, can the engine cope with the rapid shifting from spark-induced ignition and compression ignition efficiently and with finesse under varied conditions?