The world of automotive engineering is filled with fascinating innovations, but few are as intriguing and occasionally perplexing as the rotary engine, often called the Wankel engine. These engines, known for their smooth power delivery and compact size, offer a distinct alternative to the more common reciprocating piston engine. The story of cars that have rotary engines is a tale of engineering ambition, performance potential, and, ultimately, some challenges that kept them from widespread adoption. We’ll delve into some examples and consider the unique characteristics that set these vehicles apart.
The Allure of the Rotary Engine
What makes the rotary engine so special? Unlike piston engines that rely on up-and-down movement to generate power, rotary engines use a triangular rotor spinning within a housing. This simpler design promises several advantages:
- Fewer Moving Parts: The rotary engine has significantly fewer moving parts compared to a piston engine, potentially leading to greater reliability.
- Smooth Power Delivery: The continuous rotation of the rotor results in exceptionally smooth and vibration-free power delivery.
- High Power-to-Weight Ratio: Rotary engines can produce a lot of power for their size and weight, making them attractive for performance applications.
Notable Cars with Rotary Engines
Several manufacturers have experimented with rotary engines, but one name stands out above all others: Mazda. Let’s look at some key examples:
Mazda RX-7
The RX-7 is arguably the most iconic rotary-powered car. Spanning three generations (FB, FC, and FD), the RX-7 became synonymous with the Wankel engine. The later FD generation, in particular, is highly sought after for its stunning design and exhilarating performance. Its lightweight construction and powerful turbocharged rotary made it a true sports car icon.
Mazda RX-8
The RX-8 was Mazda’s successor to the RX-7, continuing the rotary tradition with the Renesis engine. While it offered a unique four-door coupe design and excellent handling, the RX-8 faced challenges with reliability and fuel economy, ultimately leading to its discontinuation.
Mazda Cosmo
The Mazda Cosmo, introduced in the late 1960s, was the first mass-produced rotary-powered car. It showcased the potential of the Wankel engine and paved the way for future rotary models.
The Challenges of Rotary Engines
Despite their advantages, rotary engines have faced several challenges that have limited their widespread use:
- Fuel Efficiency: Rotary engines are generally less fuel-efficient than comparable piston engines.
- Emissions: Meeting stringent emissions regulations has been a persistent hurdle for rotary engines.
- Apex Seal Wear: The apex seals, which seal the combustion chambers, are prone to wear, requiring eventual replacement.
A Comparative Look: Rotary vs. Piston
Here’s a simple table comparing rotary and piston engines:
| Feature | Rotary Engine | Piston Engine |
|---|---|---|
| Moving Parts | Fewer | More |
| Power Delivery | Smooth | Potentially Vibrating |
| Fuel Efficiency | Generally Lower | Generally Higher |
| Complexity | Simpler Design | More Complex Design |
The future of cars that have rotary engines remains uncertain. While Mazda has hinted at a possible return of the rotary engine, it’s likely to be in a different form, perhaps as a range extender for electric vehicles rather than as a primary power source. The dream of a widespread rotary revolution may have faded, but the legacy of these unique and innovative engines will continue to fascinate automotive enthusiasts for years to come.
