Low-displacement, turbo engines produce good efficiency but within a narrow power band.

In the race to hit future fuel economy requirements, Mazda believes that its new Skyactiv-X engine is a better alternative than the modern trend of automaker’s using small-displacement, turbocharged powerplants. The Japanese automaker’s upcoming powertrain family uses spark-controlled compression ignition, which means that combustion process generally happens without using the spark plugs. Instead, the mill operates more like a diesel by compressing the air-fuel mixture until it ignites. 

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"We don't necessarily believe in what the other guys are doing," Mazda North America powertrain engineer Jay Chen told Road & Track. "We believe the internal-combustion engine is here to stay, we believe our approach is better."

“Drive your Mazda3 in a lower gear. Then you'll know exactly what this drives like," Chen told Road & Track about the experience of operating the Skyactiv-X engine.

Mazda’s engineers believe that the recent trend of automaker’s using low-displacement, turbocharged engines and CVTs is simply a way to earn good numbers in fuel economy tests. The firm thinks these powertrains have a narrow band of operating at peak efficiency, which means they generally aren’t very good to drive on regular roads.

Mazda sees that turbocharging has its uses, though. For example, the company’s new SKYACTIV-G 2.5 T is a 2.5-liter turbo four-cylinder that produces 250 horsepower (186 kilowatts) and 310 pound-feet (420 Newton-meters) of torque in the CX-9 and upcoming 2018 Mazda6 (above).

The first Mazda vehicles with Skyactiv-X engines will arrive in 2019, and there will be a plug-in hybrid version in 2021. Chen told Road & Track that the current-generation Miata won’t be among the models getting the new powertrain tech. Spy photos show the automaker already testing the Skyactiv-X tech on the road under the hood of modified examples of the current Mazda3.

Source: Road & Track

Mazda3 Spied Testing Skyactiv-X Engine