The Rise and Fall of the Rotary Engine: Cars That Dared to Be Different

The internal combustion engine, the dominant force powering automobiles for over a century, has seen numerous variations and innovations throughout its history. One such departure from the conventional reciprocating piston design is the Wankel engine, also known as the rotary engine. This unique powerplant offered several advantages over traditional engines, but also faced challenges that ultimately limited its widespread adoption.

This article delves into the history of the Wankel engine, exploring the cars that dared to be different by incorporating this unconventional technology. We’ll explore the ingenious design of the rotary engine, its advantages and disadvantages, and why it captured the hearts of engineers and car enthusiasts alike.

The Visionary Engineer: Felix Wankel and the Rotary Engine

The story of the rotary engine begins with Felix Wankel, a brilliant German engineer who envisioned a simpler, smoother, and more powerful alternative to the piston engine. In the 1920s, Wankel began developing his revolutionary design, which replaced the pistons and cylinders of a traditional engine with a rotating combustion chamber and a triangular rotor-shaped piston.

This design offered several theoretical advantages:

• Simpler Design: The rotary engine has fewer moving parts compared to a piston engine, potentially leading to greater reliability and lower maintenance requirements.

• Smoother Operation: The rotary engine’s continuous, rotational motion inherently creates a smoother power delivery compared to the reciprocating motion of pistons in a traditional engine.

• High Potential Power Output: The compact design of the rotary engine allowed for a high power-to-weight ratio, making it attractive for performance-oriented vehicles.

Pioneering the Rotary: Cars that Embraced the Wankel Engine

Despite initial skepticism, Felix Wankel eventually secured licensing agreements with various automakers in the 1950s and 1960s. Here are some of the most notable cars that incorporated the Wankel engine:

• NSU Ro 80 (1967): Often considered the first mass-produced car with a Wankel engine, the NSU Ro 80 was a technologically advanced luxury sedan. While praised for its smooth and powerful engine, the Ro 80 suffered from reliability issues and fuel consumption concerns.

• Mazda Cosmo Sport (1967): Mazda became synonymous with the rotary engine, and the Cosmo Sport was the first of many rotary-powered sports cars from the Japanese automaker. This sleek coupe showcased the potential of the Wankel engine for performance applications.

• Mazda RX-7 (1978-2002): Arguably the most iconic rotary-powered car, the Mazda RX-7 enjoyed a long production run and gained a cult following among driving enthusiasts. Its lightweight design, high-revving rotary engine, and sharp handling made it a legend in the sports car world.

• Citroën GS Birotor (1973): Even European manufacturers experimented with the Wankel engine. The Citroën GS Birotor was a unique offering, featuring a Wankel engine paired with a conventional piston engine for improved fuel efficiency.

These are just a few examples, and other automakers like Mercedes-Benz and Chevrolet also explored the Wankel engine in concept cars and prototypes.

The Challenges of the Rotary Engine: Why Wankel Power Didn’t Take Over

While the Wankel engine offered intriguing advantages, it also faced significant challenges that hampered its widespread adoption:

• Fuel Efficiency: Rotary engines typically consumed more fuel compared to piston engines of similar power output. This became a major concern during the oil crisis of the 1970s.

• Emissions: Early rotary engines struggled to meet stricter emissions regulations, particularly regarding hydrocarbon emissions.

• Apex Seal Wear: The triangular rotor seals in a Wankel engine were prone to wear, potentially leading to power loss and oil consumption issues over time.

• Manufacturing Complexity: Despite having fewer moving parts in theory, the precise tolerances required for the rotary engine’s housing and seals made it more complex and expensive to manufacture compared to some piston engines.

These challenges, coupled with the continuous development of more efficient and cleaner piston engines, ultimately led to the decline of the Wankel engine in passenger cars. Mazda remained the sole manufacturer of rotary-powered cars until 2012, when the RX-7 went out of production.

The Future of the Rotary Engine: A Potential Resurgence?

Despite its past challenges, the Wankel engine hasn’t completely faded away. The inherent smoothness and potential for high power output continue to hold appeal for some engineers. Here are some reasons why the rotary engine might see a resurgence in the future: