Sunday, October 21, 2012

It's Miller Time - The Mazda Millenia S and the Miller Cylce Engine

Part of my Sunday morning was spent wandering around the LKQ salvage lot looking for one black floor mat, a stock air cleaner that will fit around a Holley, and any master cylinder with a vertical bolt pattern, the last which evidently only exists in Simcas. While taking a stroll through the import section, I stumbled across this Mazda Millenia S with the footnote-in-the-thermodynamics-book Miller Cycle KJ-ZEM V6 engine. For more details on the Miller Cycle and some more pictures, hit the jump.

The Miller Cycle employed in the Mazda involves using long and late intake valve opening duration paired with some sort of artificial aspiration, in this case a supercharger, to make up for the lost volumetric efficiency in the first few degrees (47 to be exact) of the compression stroke. This gives a static compression ratio of 10:1 while the dynamic compression ratio is somewhere around 8:1, giving cooler combustion temperatures for lower knock sensitivity and less back work in compressing air under light engine loads. Boosting the motor one bar over atmospheric pressure with the Lysholm blower is more efficient than using that extra 20% of the intake stroke. The result is a motor with a high specific output and fairly low consumption. Although it's light, powerful, and compact, it comes at the cost of complexity. I'm not exactly sure what brought this car to the salvage yard but I can imagine that there is a lot to go wrong in this motor and its subsystems.

For more information on Mazda's interesting lineup of sixes in the 90's like the MX-3's 1.8l V6, head over to the Mazda V6 Guide on AutoSpeed


  1. IMO, Mazda makes sport-oriented vehicles that are fun to drive and worth the money. Sad that the Mellinea discontinued a long time ago. Not to worry, one of their upcoming concepts will take place of that car. I can't wait to get a Mazda in the future cause their cars define the future as well. I'm also glad I compared other brands to Mazda otherwise I won't have to end up with a bland car. thanks, @Britney

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