The Wankel rotary still lives, and its Japanese builder finds a niche

While the rest of the world gives it short shrift, Toyo Kogyo (TK) of Japan remains dedicated to the rotary engine.

Conceived by Felix Wankel, who still lives in West Germany, the rotary engine uses rotors instead of pistons, although it still is a 4-cycle heat engine that injects fuel, ignites it, and runs.

West Germany's Audi-NSU, a division of Volkswagenwerk AG, has done extensive work on the engine - marketing the problem-plagued Wankel-powered RO-80 until a few years ago - it is the Japanese who have remained committed to the rotary, spent huge sums to perfect it, and continue to hold on to their dream of a viable automotive plant for the future.

Toyo Kogyo was licensed by NSU some 20 years ago to explore the engine.

The only rotary-powered car sold in the US is the Mazda RX-7, built by TK. However, TK, which markets its vehicles under the Mazda nameplate, now has introduced an upgraded Wankel engine with a 6-port induction system (RE 6PI) in its top-line automobile, the luxury Luce series. The other rotary systems have four ports.

Why six ports instead of eight or more? ''It's the best trade-off of efficiency and simplicity,'' a Mazda engineer explains.

''The RE 6PI is simply the latest step in tapping the tremendous potential of the rotary engine,'' says Kenichi Yamamoto, managing director of advanced development for TK. ''The new induction system boosts fuel economy without hampering performance, making the engine an even more viable power plant for the future.''

Toyo Kogyo first signed a licensing pact with NSU-Wankel in 1961 and began full-scale research and development work on the engine. Six years later the Japanese carmaker introduced the world's first twin-rotor rotary-engine sports car, the Mazda Cosmo (110S).

Since then the company has sold more than 1.2 million Wankel-run cars, including nearly a half million in the US alone - RX-2, RX-3, RX-4, Cosmo (RX-5) , and RX-7.

It has been a rough road for the engine all the way.

The auto industry, in fact, snubs any marked shift in power-plant technology because of the huge capital costs involved in making a switch.

Toyo Kogyo almost fell victim to the Arab oil embargo in 1973-74 because of a precipitous drop in sales and was saved only by a vast commitment on the part of the Japanese banks and trading companies. The US sales operation also was devastated and subsequently revamped.

Poor mileage was at fault; the rotary engine gave far fewer miles per gallon than a piston-engine vehicle of comparable weight. Then there were mechanical problems with the engine, such as apex seals.

Since then, TK has eliminated the seal issue and dramatically stepped up mpg. Even so, the rotary engine, while an energetic performer on the road, still does not give as high mileage as many of the 4-cylinder piston engines being produced in the US, Europe, and Japan.

Undaunted, the people at TK press on.

Audi-NSU, which came up with a new rotary engine a few years ago, opted to push it aside because of a change in the automobile market and other needs for the production facilities.

Too, General Motors spent an estimated $50 million on the rotary, only to dump it on the eve of former president Edward M. Cole's retirement in the mid- 1970s. Mr. Cole was a strong backer of the Wankel.

Mazda already has sold at least 175,000 RX-7s in the US since the car's introduction in mid-1978.

''Most competing car companies will concede that the rotary is compact, light , has fewer parts, and gives outstanding performance which is relatively free from vibration,'' asserts Eric Sundstrom, general manager of Mazda Motors of America (East) Inc., one of two distributors of Mazda cars in the US. The other distributor is headquartered in Chicago.

''But everybody always brings up fuel economy,'' he adds. ''They point out that rotaries back in 1973 and 1974 got about as much fuel economy as a Rolls-Royce with a leak - or so the EPA (Environmental Protection Agency) said.

''That was a bad rap and even EPA sent out a revision, but it almost wrecked Mazda in the US.''

The RX-7, equipped with a catalytic converter, carries an EPA ''city figure'' of 21 mpg although the highway number is 30. This, asserts Mr. Sundstrom, ''is competitive with Camaro, Trans Am, and the Mustang V-8.

Mazda's target for the current two-rotor rotary is more than 23 mpg within the next several years, according to Sundstrom. While the higher-mileage RE 6PI engine will not be sold in the US in 1982, ''it is still being studied for the US market,'' says Mr. Sundstrom.

Beyond that, he says that TK engineers may supercharge the rotary.

''What if you made the supercharging mechanism part of the engine to contrive an increase in low- and mid-range pickup and reduce engine displacement by the amount of increase in torque?'' he asks.

''Reported test results show that low/mid-range torque can be improved 30 percent via any kind of supercharging,'' he says.

''If you reduce engine displacement this amount, you get nearly 30 percent increase in fuel economy while maintaining performance at approximately the original level.

''So, in this area too, the rotary shows terrific potential,'' he concludes.

The trouble for TK is that no one seems to be listening.

Meanwhile, the Japanese car company is expanding its service network in the US with the opening of a highly automated, $1.5 million parts depot and service-training facility in Mansfield, Mass., one of three on the East Coast.

''The new Mansfield depot stocks only fast-moving parts,'' reports Peter C. Charbonneau, depot manager, ''and overnight delivery is promised to Mazda dealerships in the six New England states and upstate New York.'' Slower-moving parts are shipped from Jacksonville, Fla., headquarters of Mazda Motors of America (East), Inc.

Mazda has been selling cars in the US for the last 12 years.

What made it different in the early days was its top-heavy emphasis on the rotary engine, starting with the RX-2 - the car that went hummmm. Remember the ads? The soon-to-arrive Arab oil embargo, however, forced the company to shift gears.

Even so, the rotary-powered RX-7 is the fastest-selling two-seat sports car in the US.