Rotary Engine

History of Rotary

Engineering History
From the Cosmo Sport to Multiple Rotaries
Development of Low-Emission Rotary Engines

After successfully commencing mass production of the Type 10A dual-rotor RE with the Cosmo Sport in 1967, Mazda decided to expand its application beyond the limited sports car market, and began installing it in large-volume sedans and coupes in 1968. In an effort to meet demand from global markets, the company also decided to export its rotary-engine vehicles.

Exports to the United States began In June 1970, when the U.S. government was in the process of introducing the Muskie Act, the country's most stringent automobile emission standards to date.

As far back as 1966, while still in the early stages of rotary engine development, Mazda had begun to focus on reducing exhaust emissions. Compared with the reciprocating engine, the rotary engine tended to emit less NOx but more hydrocarbons. To clear the automobile emission standards set by the Muskie Act, Mazda successfully developed a thermal reactor system that burned hydrocarbons in the exhaust gas to reduce the emissions.

The Model R100 (called the Familia Rotary Coupe in Japan) became the first product to be exported to the U.S., and equipped with the thermal reactor system, it met the current emission standards. When Mazda reported that its rotary engine could meet the standards in a public hearing with the U.S. government, other auto manufacturers around the globe reacted with surprise. Many had declared that meeting the Muskie Act standards so soon was impossible. Then, in February 1973, Mazda’s rotary engine passed the U.S. EPA Muskie Act test as promised.

An engine of Familia Rotary Coupe
Engine from the Familia Rotary Coupe

Meanwhile, in the Japanese market, Mazda launched the first low-emission production vehicle in November 1972. This was the Luce AP, powered by the Type 12A (2 x 573cc) rotary engine, it came equipped with Mazda’s Rotary Engine Anti-Pollution System (REAPS).

The Phoenix Project

In the 1970s, the world entered a stormy period after being hit by two major oil shocks. In response to the situation, automotive manufacturers began to concentrate on improving fuel efficiency. Development of a highly fuel efficient rotary engine became paramount to Mazda, so it initiated the "Phoenix Project," an R&D venture which aimed to improve fuel efficiency by 20 percent after just one year, and ultimately 40 percent.

During the project, Mazda engineers worked hard to solve technical issues by improving the thermal reactor systems that purified exhaust emissions while working on lean-burn settings for carburetors. A year later, the 20 percent improvement in fuel efficiency was successfully attained. Further development, including enhancing reaction efficiencies by incorporating a heat exchanger in the thermal reactor system, finally led to the ultimate goal of a 40 percent improvement.

The success of the Phoenix Project was reflected in the sporty Mazda RX-7 (called the Savanna RX-7 in Japan) which was launched in 1978. As suggested by the project name Phoenix, it proved to the world that the rotary engine was here to stay.

Mazda continued with its R&D and soon fuel efficiency was even further improved with the world's first catalytic converter system for the rotary engine, which maintained lean-burn and purified exhaust emissions at the same time. Through fundamental engine improvements and newly developed systems, including the reaction-type exhaust manifold, the high-energy ignition system, split secondary air control, and the two-stage pellet catalyst system, Mazda finally completed the Lean-Burn rotary engine and launched it onto the market.

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Related information

The Luce AP

The Luce AP
The second generation Luce made its debut in Japan in 1973 and in 1974 the first low emission version with a 13B engine was introduced.

Lean-Burn Rotary Engine

Lean-Burn Rotary Engine
By introducing a catalytic converter to purify exhaust emissions became possible.

How a Rotary Engine Works

Watch an easy-to-understand animated explanation of how a rotary engine works.