The Mazda3’s familiar powertrain line-up features the 2.0-litre SKYACTIV-G petrol in two outputs and a pair of SKYACTIV-D diesel engines. These ultra-efficient award-winning engines feature Mazda’s i-stop stop-start system, which delivers the world’s fastest restarts on a diesel engine.
When developing the latest range of SKYACTIV engines, Mazda’s engineers eschewed the current trend for downsizing and opted instead for a fundamental rethink that would allow them to optimise every aspect of these innovative new engines. The result is a combination of exceptionally high levels of economy, refinement and flexibility without compromising performance.
The 2.0-litre petrol enginefeatures a radically high compression ratio of 14:1 combined with lightweight all-alloy construction and intelligent direct injection. Particular attention was also paid to the reduction of inertial weight and mechanical friction, with examples being lighter pistons, piston pins and conrods.
Equal attention to detail was applied to the development of both the Mazda3’s SKYACTIV-D engines. Focus was again applied to optimisingcompression ratios to achieve superior air-fuel mixture levels and more uniform combustion. Featuring a low 14:1 compression ratio, the 2.2-litre SKYACTIV-D’s lowered compression ratio reduces compression temperature and pressure at top dead centre decrease. Consequently, ignition takes longer even when fuel is injected near top dead centre, enabling better mixture of air and fuel. This alleviates the formation of NOx and soot because the combustion becomes more uniform without localised high-temperature areas and oxygen insufficiencies.
The SKYACTIV-D’s cylinder block is made from aluminium, rather than cast iron, saving a full 25kg over Mazda’s last-generation large capacity diesel engine. One of the key challenges of a low-compression diesel engine is that it results in a compression-ignition temperature that is too low for reliable cold starts and efficient cold-temperature operation. To combat this, Mazda’s powertrain engineers opted for advanced ceramic glowplugs that deliver exceptional cold-start performance, multi-hole piezo injectors capable of handling up to nine injections per cycle for optimal combustion performance, a variable valve lift system that reuses hot exhaust air to stabilise ignition and a bi-turbo layout in which one small and one large turbo are selectively operated according to driving conditions.
In a UK marketplace that now sees 42 per cent of C-segment diesel sales delivering sub 100g/km CO2 emissions, Mazda’s SKYACTIV-D 1.5 ensures the Mazda3 is now a strong contender in this competitive area of the family hatch market. With 270Nm of torque and 0-62mph performance of 11.0 seconds, the Mazda3 SKYACTIV-D 1.5 delivers the no compromise blend of performance, refinement and efficiency demanded by customers in this sector. Developed with same Defy Convention approach as the larger SKYACTIV-D 2.2, the smaller capacity diesel features an exceptionally low 14.8:1 compression ratio that sets new standards of efficiency and performance.
Designed to deliver excellent flexibility at cruising speeds and strong in-gear response, the 1.5-litre SKYACTIV-D has peak torque of 270Nm available between 1,600 and 2,500rpm. The advanced engine features high-dispersion solenoid fuel injectors to suppress cooling losses and provide the optimum injection pattern for the given driving conditions. This improves both combustion efficiency and engine refinement levels. In addition, the combustion chamber features a unique ‘shouldered’ design to suppress flow around the lip of the chamber and prevent combustion gas cooling.
With the launch of the Mazda3, the 1.5 and 2.2-litre SKYACTIV-D engines have been upgraded to improve performance and refinement.Both engines now feature Transient Control, which by reducing turbo lag and boosting torque, provides a more positive throttle response, ensuring that the Mazda3’s diesel engines respond better than ever to the driver's intentions.
Refinement has also been enhanced thanks to the introduction of Mazda’s Natural Sound Smoother (NSS) technology to both SKYACTIV-D engines. Already a feature on the Mazda CX-3 and Mazda2, it reduces knock noise during starting and low-speed acceleration. It works by suppressing the resonance from the piston and connecting rod using a dynamic damper installed to the inside of the piston pin. By ensuring that the pressures occurring during the pre, main and post combustion stages cancel each other out, vibration and resonance is reduced. In addition, the three critical frequency bands in which engine components typically vibrate most loudly are suppressed by Mazda’s Natural Sound Frequency Control. It deactivates the engine timing in 100 microsecond waves thereby causing the pressure waves caused before, after and during combustion to cancel each other out, with the end result being less combustion induced vibration. Working in unison these two technologies have reduced diesel engine resonance in the cabin of the Mazda3.
As before, the Mazda3 hatchback and Fastback range is available with choice of six-speed SKYACTIV-Drive automatic and six-speed SKYACTIV-MT manual transmissions. Available with all engines across the full hatchback and Fastback range, the lightweight SKYACTIV-MT delivers the same crisp and precise gear changes, as those enjoyed by Mazda MX-5 drivers.
Drivers of both the 120ps SKYACTIV-G and 150ps SKYACTIV-D hatchbacks can opt for the SKYACTIV-Drive six-speed automatic. It features a torque converter with a lock-up clutch, which locks the torque converter’s turbine to the impeller to improve fuel economy and enhance the driver’s feeling of connectedness.
To boost shift quality and response, the SKYACTIV-Drive gearbox also features a direct linear solenoid system that accurately controls hydraulic pressure for exceptional responsiveness. The result is a smooth and highly efficient gearbox that delivers strong economy along with a direct feel and quick shift pattern – qualities aimed squarely at the enthusiastic driver.
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