We are happy, but a bit surprised to learn that Mazda has joined the U.S. Migration to diesel even before Ford in offering their first 4 door sedan with a diesel powered drive train in the U.S. market. Meet the Takeri.
The 2.2-liter Sky-D (other sizes are likely to follow) meets Euro 6 and U.S. Tier 2 Bin 5 emissions standards without using any NOx aftertreatment such as urea injection. Now that the vehicle passed, Mazda may offer this 2014 model vehicle during the 2013 calendar year.
This diesel engine is impressive. Mazda decreased the compression ratio from 16.3:1 down to 14:1 in this diesel engine. Doing so reduces cylinder pressures, and therefore temperatures, which reduces NOx production and also allows the fuel to mix better, avoiding locally rich areas that produce soot. Mazda claims that the lower friction from the reduced cylinder pressure alone is worth a 4- to 5-percent gain in fuel economy. This reduced internal forces also allow components such as the rods and pistons to be substantially lighter. Here, too, a forged steel crankshaft replaces a cast-iron unit.
The downside to lowering the compression ratio of a diesel is that, during warm-up, the engine temperature can be too low to support proper combustion, and misfires result. To get around this, Mazda added a two-stage variable valve-lift system on the exhaust side in order to be able to create additional valve overlap. This causes the hot exhaust gases to be drawn back into the next cylinder to warm it up. Ingenious.
While the performance tests are yet to be completed, the engineers are comfortable with a projection in the low 40’s for mpg for combined city/hwy. This is competitive with VW’s offerings and would support right at 50mppg avg running B20. To the Mazda Executives, “Build it and they will come”.
Now, Mazda says:
“The on-sale date for Mazda6 Skyactiv-D clean-diesel has been moved to late-spring 2014, to accommodate final emissions testing and certification….More information on the Skyactiv-D clean diesel Mazda6 will be available closer to the on-sale date.”