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Comment by rikthevik | Hacker News Reader

If I remember correctly the engine in the Mazda Millenia was a Miller cycle engine and did something unconventional like this. Props to Mazda for trying new stuff.

https://en.wikipedia.org/wiki/Mazda_Millenia

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Miller cycle (IIRC) was a bit different. It simply kept the intake valves open longer and used boost from it's supercharger to emulate a valve "closing". It used a boost level that was significantly higher than a supercharged Otto cycle would use. Volkswagen is doing something similar with the EA888.3B (B cycle) motor that is in the most recent Tiguans. https://www.motortrend.com/features/inside-volkswagen-ea888-...

This six stroke is doing something a bit more complex...more impressive, IMHO. Similar in complexity to what Nissan is doing with their variable compression engine they are currently using https://www.nissan-global.com/EN/INNOVATION/TECHNOLOGY/ARCHI...

There was also a 6 stroke diesel a while back that injected water into the empty cylinder after the exhaust stroke to gain an extra compression stroke from waste heat...Bruce Crower (Crower Cams fame) built one years ago but I never heard anything more about it. https://www.autoweek.com/news/a2063201/inside-bruce-crowers-...

Note that the motortrend link you give says that the Miller cycle "closes the intake valves much earlier." I'm just reading about this for the first time, but this is exactly the opposite of the description on Wikipedia [0], and from a quick glance at the patent Wikipedia is correct, and motortrend is exactly wrong here.

[0] https://en.wikipedia.org/wiki/Miller_cycle

Good note...especially since I misspoke. Apparently..it doesn't use standard Miller cycle.

They are calling it Budack cycle. https://alexsautohaus.com/whats-changed-with-volkswagens-new...

Mazda has marketed half a dozen weird engines, all of which were crap. It has been a remarkable streak of stubborn, unwanted innovation from such a small carmaker.

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