2018 Mazda6 SKYACTIV-G Cylinder Deactivation Engine – Video
Mazda6 offers two powertrain options in the U.S., starting with the torquey, fuel-efficient SKYACTIV-G 2.5 naturally aspirated engine. Mazda6’s 2.5-liter, four-cylinder engine comes with a host of upgrades to reduce internal friction and improve efficiency across all RPM, and it adds a greater level of refinement. A new technology that is unique to Mazda in North America is cylinder deactivation in a four-cylinder engine. The outside two cylinders can shut down when the vehicle is operated at steady speeds between 25 and 50 mph, but all four cylinders work instantaneously when needed for maximum performance. A centrifugal pendulum has been adopted in the torque converter of the six-speed SKYACTIV-DRIVE automatic transmission, counterbalancing any vibration that might otherwise be felt when running on two cylinders. The result is an imperceptible switchover between two- and four-cylinder modes, yet with very tangible real-world efficiency benefits.
Higher-grade models will also be available with Mazda’s award-winning turbocharged SKYACTIV-G 2.5T engine. First available in the current-generation Mazda CX-9 midsize crossover SUV, the SKYACTIV-G 2.5T is a technological tour de force that produces 310 lb-ft of torque from just 2,000 RPM and 250 horsepower on 93-octane fuel (227 horsepower with 87-octane gasoline).
Mazda’s industry-first Dynamic Pressure Turbo builds boost nearly instantaneously by using a small inlet port to force air into its turbocharger, akin to how water velocity increases when one holds his or her thumb over a hose. From there, a secondary valve can open up at higher RPM for increased airflow and maximum horsepower. A pulse-scavenging 4-3-1 manifold that prevents exhaust backpressure and helps the engine breathe freely.
Cooled exhaust gas recirculation (EGR) is used to reduce combustion temperatures, preventing knocking and therefore reducing the need for fuel-enrichment (when extra fuel is dumped into the cylinders as a means to cool the engine). Many times when turbocharged engines fail to achieve EPA-estimated fuel-efficiency numbers in the real world, it is because laboratory tests don’t replicate the higher-load driving styles that necessitate fuel-enrichment.
In too many instances, turbocharged engines are mated to continuously variable automatic transmissions (CVT), operating in a narrow band of efficiency, sacrificing a connectedness between driver and car—a valued characteristic of all Mazda vehicles called Jinba Ittai. Mazda’s six-speed SKYACTIV-DRIVE automatic transmission, paired as standard to the SKYACTIV-G 2.5T engine, keeps its torque converter locked through most of its operation, giving a more connected sense of controllability than many other automatic transmissions.
Both engines complement Mazda6, with the naturally aspirated engine serving as an all-around efficient, responsive powertrain and its turbocharged sibling amplifying the driving performance for which Mazdas are known.
Finally, as a champion of the manual transmission, Mazda6 will continue to offer the SKYACTIV-MT, paired with the SKYACTIV-G 2.5 engine.