1967 Mazda Cosmo Sport 110S: Honorable rotary origins

February 24, 2012 | By | Reply More
1967 Mazda Cosmo Sport

1967 Mazda Cosmo Sport 110S

The thrill was back, they told us, and how right they were. Emissions controls, beginning in the 1968 model year, had gradually turned most new cars into performance eunuchs. But Mazda was different, and the power of its Wankel engine made the phrase “rotary rocket” part of the automotive lexicon. The humdrum sedans the engines came in were tolerated and the poor gas mileage, in part a result of the “rich burn” thermal reactor emissions control system, was considered a necessary evil. Besides, gas was cheap—30 cents per gallon or less—and the rotary would burn the cheapest.

Then came OPEC oil embargo and the first of the energy crises. Toyo Kogyo, which in the U.S. had gone from 649 cars sold in 1970 when the rotary-engined Mazda R100 was introduced to sales of more than 100,000 in 1973, had its entire corporate existence shaken to the roots. Retrenching, the company dumped plans to scrap its piston engines, and offered models such as the Mazda 808, miserly but miserable. But about when it appeared that Mazda was about to become just another small car company, what would appear but the Mazda RX-7. Fast, beautiful, the first affordable sports car in years, it was the company’s salvation. Why hadn’t Mazda thought of it before?

1967 Mazda Cosmo Sport dash

The dash of the 1967 Mazda Cosmo Sport was very business-like. (Click to enlarge image).

Fact is, it had. Fact is, the first rotary-engined car Mazda produced was a sports car. Fact is, the car—the Mazda Cosmo Sport—was very, very good.

It was the culmination of Mazda’s rotary engine efforts which had begun in 1961, only a year after Mazda’s first automobile, the tiny twin-cylinder Mazda R360, had rolled off the Hiroshima assembly lines. Having bought production rights from NSU, all Mazda had to do was make it work. Only in December of 1959 had the German car and motorcycle maker first displayed a running prototype, and durability, oil control and satisfactory idling were still unsolved problems. There was no guarantee that the rotary would ever be usable as an automotive powerplant.

But it had too much potential to be ignored. It seemed ideal for micro-cars, and the problems were solved one by one. First a new apex seal design, then a new seal material. Dual ignition, side ports replacing NSU’s peripheral ports, and twin rather than single rotor design all combined to smooth idling. The problem of unequal heat distribution was solved by axial, or lengthwise, coolant flow, with the hot coolant sent back over the “cool” side of the engine. In 1967, Toyo Kogyo finally had a marketable engine.

Marketable? It was a firecracker. With twin rotors and a pair of distributors, the Asian Wankel had two intake ports per cylinder and one triple-barrel carburetor. The primary carb throat fed the inner port of each chamber, while each secondary had an outer port to itself. Not only did the engine have progressive carburetion, but the port placement also affected induction timing. Opening the secondaries would have the same effect as changing to a longer duration cam—with the engine running—on a piston engine. Displacing 982cc, the rotary produced 110 hp at 7000 rpm and 96 lb-ft of torque at 3500.

This was just too good (not to mention too much) for a micro-car, so Toyo Kogyo discarded those plans and wrapped the Wankel in a genuine sports car—the 110S—or by another name, the Mazda Cosmo Sport.

1967 Mazda Cosmo Sport taillights

Taillights...or rocket boosters...1967 Mazda Cosmo Sport. (Click to enlarge image).

It was a true two seater (contrary to Japanese custom), the layout conventional—front engine with rear drive—but sophisticated.

Front suspension was by A-arms and coil springs, while the rear was a De Dion system. Braking was by discs and drums respectively. The transmission was an all-synchro four-speed, and with a final drive ratio of 4.11:1, the Mazda Cosmo Sport 110S promised a top speed of 115 mph.

Of course, the Japanese had a reputation for “borrowing” ideas and, already having gone to Germany for an engine, drew exterior styling inspiration from Italy (though transliterated into Japanese) and interior design from Great Britain. Actually, the styling has been the most criticized feature of the Mazda Cosmo, “Japanese sci-fi” being the most common epithet. In truth, there is nothing wrong with the basic shape—nothing that some sheet metal de-ornamentation wouldn’t cure. The worst part was the front flanks, where the wheel well eyebrow, side vent and waistline sculpting compete for visual interest.

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Category: Times Were

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