Mazda Unveils 1.5-Liter Skyactiv Diesel

Mazda Motor Corp. says the new 1.5-liter clean diesel it will debut in Japan later this year expands on the Skyactiv-D technologies introduced in the company's 2.2-liter oil burner two years ago.

The new Skyactiv-D 1.5 powerplant will be available in Japan in the redesigned Mazda2/Demio subcompact car. Mazda has not indicated which other markets will get the new diesel.

Mazda boasts that the little engine's 14.8:1 compression ratio is lower than any other small-displacement diesel. Special stepped egg-shaped piston heads help avoid cooling loss by reducing contact between the combustion flame and the cylinder wall.

Like Mazda's 2.2-liter diesel, the little 1.5-liter unit can meet Europe's Euro 6 and Japan's advanced emission targets without requiring an expensive exhaust aftertreatment system to control oxides of nitrogen. The company has said that lowering costs for diesels is a key factor in coaxing Japanese consumers to consider such engines.

The 1.5-liter diesel is rated at 104 hp. Mazda likens the unit's 184 lb-ft of torque to that of a typical 2.5-liter gasoline engine. Fuel-saving elements include a variable-geometry turbocharger, water-cooled intercooler and a combination of high- and low-pressure exhaust gas recirculation systems that extend the range of homogeneous lean burn.

Among other improvements relative to the 2.2-liter diesel are reduced mechanical friction and an insulation strategy to offset the increase in cooling loss associated with small diesels.

Mazda will pair the Mazda2 diesel with such Skyactiv technologies as automatic stop-start, brake energy recovery and the company's most efficient transmissions. The combination promises "drastically" improved fuel economy, according to Mazda.