If you were a contestant on the game show Jeopardy! and selected the category “Sports Car Racing” for $600, host Alex Trebek might give you this answer: “This car brand was the winningest brand ever in the International Motor Sports Association (IMSA) GT championship.” You would probably respond incorrectly, as most of us would, with “What is Corvette?” or “What is Porsche?” The correct response is: “What is the Mazda RX7?” The Mazda RX7 took home the IMSA GTU (for engines under two liters) championship for nine consecutive years between 1979 and 1987 – a truly incredible accomplishment.
The rotary-engined Mazda RX7
New for 1979, the Mazda RX7 had all the attributes you could ask for in a two-seat sports car. Thanks to its lightweight and compact rotary engine, the RX7 was light, weighing only about 2,400 pounds; it was well-balanced with a 51/49 front/rear weight distribution; and it had a low center of gravity, quick steering, and a firm suspension. The engine was so compact it could be located low in the chassis behind the axis of the front wheels. This gave the RX7 a front mid-engine layout accounting for the near-perfect balance and low center of gravity.
The carbureted two-rotor engine had displacement equal to 1.2 liters and produced 100 horsepower, enough to propel the RX7 from 0 to 60 mph in 9.3 seconds and turn the quarter mile in 17 seconds at a speed of 80 mph. For a price of about $6,400 for the base model, the RX7 was less expensive than its competition, and would leave them in the dust on the street. Car and Driver magazine said, “The RX7 is unquestionably this year’s sports-car coup. It sneaks into the fray with an unsophisticated chassis layout, a tiny beer keg of a motor, and blows off well-seasoned leaders – Datsun’s 280Z and Porsche’s 924 in particular – by at least a thousand dollars in price and precious seconds in acceleration time.” The RX7 continued to impress, making Car and Driver’s Ten Best list five times.
Advantages of a rotary engine
Mazda is a small fish in the automotive sea. But their small size hasn’t prevented them from taking a gamble or two by making cars that the big guys lack the foresight to consider. In the early ‘60s, Mazda president Tsuneji Matsuda believed the company needed to develop a unique technology to survive against the larger competitors, and established the goal of commercializing the rotary engine. The rotary engine had several advantages over the usual multi-piston engine, such as:
- Smoothness of operation
- Very compact with small size and light weight
- Able to achieve high rpms
- High power-to-weight ratio
Mazda acquired a license from NSU, who then owned the rights to the Wankel rotary engine, as the first step in their goal. NSU in Germany had built two models of rotary-engined cars, but it was obvious that some additional development work was necessary before the engine could compete with the piston engine on a commercial basis. In Mazda’s newly established rotary engine research department, the engineers attacked the engine’s shortcomings with the intensity and devotion of samurai warriors.
Mazda succeeds where others falter
Mazda was one of many companies that were interested in rotary engine technology in the ‘60s and that licensed the technology. All the others were put off by the rotary’s poor fuel economy and exhaust emissions, and they were really stymied by the quick wear of the apex seals that resulted in engine damage. The rotors of a rotary engine resemble a triangle (visualize a triangle with sides that curve slightly outward) and the apexes slide against the inside of a housing. It is imperative that the apexes seal against the housing as the rotor rotates. Solutions to the apex seal problem escaped everyone – everyone, that is, except Mazda.
Mazda engineers achieved a breakthrough in 1963 with improved apex seals made from aluminum-carbon composite material. These seals would reliably seal against the housing for a long time without damaging the interior surface of the housing, a major step in the commercialization of the rotary engine. On May 30, 1967, Mazda introduced the Cosmo Sport, the world’s first production car powered by a rotary engine.
RX7 conquers affordable sports car market
Introduced in 1978 as a 1979 model, the RX7 had what appeared to be formidable competition in the affordable sports car market – the Datsun 280ZX, Porsche 924, Corvette, MGB, and a host of others. The glowing reviews from all the car magazines got the word out about the RX7 and sales took off. As Motor Trend said, “There’s simply nothing else out there with the RX7’s combination of price, performance, quality and styling.”
Over 19,000 RX7s were sold in 1978, and the following year almost 55,000 new RX7s were on the road. 1979 would turn out to be the RX7’s biggest sales year, but sales were relatively consistent until 1985, the final year of the first version of the RX7. A total of 370,608 RX7s were sold in eight years. Mr. Matsuda and Mazda succeeded in achieving their goal of commercializing the rotary engine, and also established Mazda as an automotive innovator.
Oh, and don’t forget about the astounding racing career of the RX7. You never know when Jeopardy! might call and invite you to be a contestant.
Mazda RX7 History – http://www.mazda-rx7.info/history/
Rotary News – http://rotarynews.com/node/view/157
History of the RX-7 – http://www.angelfire.com/sc3/mazda_rx7/history%20of%20the%20rx7.htm
Wikipedia – https://en.wikipedia.org/wiki/Wankel_engine