Scott Lear
Scott Lear
8/18/08 11:45 a.m.

We owe a lot to the car companies that were brave—or desperate—enough to bring something truly new to the mass market. With trillions of dollars in earnings on the line, one can’t really blame them for playing it safe most of the time. Rather than springing some wonderful, unusual creation on the u…

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Rupert HalfDork
5/13/10 10:40 a.m.

Great Car! I'm not surprised who owns it. If there are others out there with Cosmos, RX-2s, RX-3s or series 1 RX-7s, please share your pictures with us!

GLK New Reader
7/5/19 5:19 p.m.

I agree. We should be thankful for out of the box thinking. It’s too bad the rotary is difficult to tame emissions-wise and is a bit too thirsty. A great engine that was a brave move by Mazda to mass produce nonetheless.

Brian_13 New Reader
4/14/20 1:07 p.m.

After more than half a century, the displacment calculation nonsense gets really tiresome. The article says "the four phases are happening at once in different parts of the chamber", but that's nonsense - there are three separate chambers formed by the three faces of the rotor. Yes, they're all working at different phases, but the same is true of any multi-cylinder engine, and you don't count only one of the cylinders.

The stock 10A in the Cosmos had a chamber displacement of 491 cm³, so the six chambers (three per rotor, two rotors) displace a total of 2,946 cm³. The 12A that Leno swapped in displaces 573 cm³ per chamber, for a total of 3,438 cm³. The 13A that is in all of the later Mazda Rotary cars displaces 654 cm³ per chamber, for a total of 3,924 cm³.  Yes, these are 3 to 4 litre engines.

Even Mazda (back in the day when they built these things) listed the chamber displacement and rotor count - in a form such as "654 cc x 2" for a 13B - not the actual displacement, not claiming that the actual displacement was only 1.3 L... they let people jump to that nonsensical conclusion themselves.

While the Wankel/Paschke engine design is usually praised for its smooth non-reciprocating action (which was Wankel's intent in searching orbiting rotor possibilities), and the lack of valve gear is desirable, perhaps the real brilliance was simply the packing of large displacmement into a compact package. It uses that displacement ineffectively, but it has so much displacement that even a compact car can carry enough engine for good power. The 110 hp of the stock Cosmos was good, although even in 1967 it wasn't particularly impressive output for a 2.9 L sports car engine.

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