Diesel engine fuel-efficiency – with the performance and character of a gasoline engine. Mazda’s new engine SkyActiv-X will combine the best of both worlds.

During the ongoing car show in Tokyo last week, Mazda unveiled its latest engine technology, the Skyactive-X promises amazing efficiency improvements but without compromising performance.

It is not a new form of hybrid or electric motor, but a traditional combustion engine, with a twist. It will have the torque and fuel economy of a diesel engine, but with emissions and performance as a gasoline engine.

Ordinary gasoline engines and diesel engines work a little differently. Gasoline engines (Otto engines) have spark plugs that ignite a mixture of fuel and air. Diesel engines compress the air in a cylinder before adding fuel – which is then spontaneously ignited.

One of the major differences between the two is that the spark plug of the petrol engine gives a spark, while ignition in a diesel engine occurs at multiple locations in the combustion chamber. Therefore, compression ignition (diesel) provides faster and more complete combustion – reducing the volume of fuel necessary to sustain the engine.

Now, Mazda has achieved a kind of hybrid engine between the two technologies, powered by gasoline, but with the compression ignition of a diesel engine. Their so-called “homogeneous charge compression ignition technology” is a similar technology to the Mahle jet ignition used in Formula 1.

Mazda achieved this by using a small spark plug that helps initiate the compression ignition sequence, which may be active or not depending on what is required. With only a minimal window when compression ignition is possible for regular gasoline, a few parameters are necessary to hone down to perfection for the technology to function properly.

The Skyactive-X will deliver diesel engine-like torque and fuel economy along with the higher revs and cleaner exhaust emissions typical of gasoline engines.

The technology is called Spark Controlled Compression Ignition (SPCCI) and, compared to Mazda’s current best gasoline, the new SkyActiv-X delivers 10-30 percent higher torque, 20 percent better fuel economy and overall better responsiveness.

The new compression-ignition engine combining the advantages of both gasoline and diesel engine technologies will enter production in 2020, found under the hood of a Mazda3.


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