What Are Rotary Engines and Which Cars Have Them?

During my time as an automotive engineer. I’ve had a firsthand look at how rotary engines differ fundamentally from traditional piston-powered engines. Renowned for their efficient and elegant engine design. Rotary engines operate with a simplicity of motion that’s as fascinating as it is groundbreaking. Unlike their piston counterparts, rotary engines produce power through a revolving motion, offering a smoother ride. However, due to high cost and environmental reasons, they fell out of favor. Marking the end of what many consider a bygone era in automotive design.

Interestingly, Mazda, the torchbearer of rotary engines, has been relentlessly developing hybrid models, hinting at a possible comeback. This unique type of engine is poised for a resurgence in a more environmentally friendly format. Hybrid models, specifically those being experimented with by Mazda, promise to merge the best of both worlds. The benefits of rotary’s compact, lightweight design with the environmentally-conscious, fuel-efficient advantages of hybrid technology. This potential revival could change the way we think about cars and their engines in the future. Making it an exciting time for automotive enthusiasts like myself.

What is a Rotary Engine?

In the automotive sphere, rotary engines represent a fascinating divergence from the conventional piston engine. Boasting a design that leverages a triangular-shaped rotor to accomplish the core combustion cycle steps—intake, compression, combustion, and exhaust—in a distinctly efficient manner. Originating in the 1920s, this internal combustion engine type captures interest with its unique shape and gas-tight seals. Which allow volumes of gas to expand and contract within the engine housing. Facilitating a smooth transition of air and fuel through the system. 

Unlike piston engines where pistons churn within cylinders to move the drivetrain. The rotary engine relies on the rotor spinning inside the engine. Channeling power directly to the output shaft—a step-by-step look into its operation showcases the intake valve and intake port welcoming the fuel-air mix, followed by the compression and ignition at the peak of pressure, culminating in the expulsion of gasses through the exhaust port to the tailpipe.

Despite their ingenious design enabling lighter, more compact engines capable of significant power outputs relative to their size, rotary engines are a rarer sight in vehicles today, limited to a niche selection of cars, with broader applications in trucks, boats, and even planes over decades. The rotary engine’s distinct operation, where the rotor spins. Creating gas chambers that expand and contract to perform the combustion cycle, sets it apart from types of engine that conduct work completely differently. 

This engineering marvel, while not widely used, continues to stir the imagination and passion of automotive enthusiasts and experts. Underscoring its enduring legacy and the ongoing intrigue surrounding which cars have harnessed this unique powertrain’s capabilities.

The Components of a Rotary Engine

Rotary engines, unlike their piston engine counterparts, are marvels of engineering that rely on complicated, moving parts and components to do their work. At their core, they embody a unique blend of simplicity and complexity. Making them both fascinating and somewhat esoteric in the world of automotive engineering. Their essential components are what allow them to operate in a sense that is starkly different from the more conventional engines we’re used to. Making a deep dive into these parts not just educational but necessary for those of us intrigued by how things work.

Rotor

At the heart of every rotary engine is the Rotor, a three-sided component with concave sides that form gas-tight seals when pressed against the housing. This component resembles a high-tech spirograph in an offset way, rotating inside the engine to create three individual combustion pockets. Each face of the rotor has an inlet pocket, allowing for a greater volume of gas to enter, enhancing the displacement rate as it spins on gears around a shaft positioned off-center. This eccentric movement, much like a planet moves around a sun yet also rotates on its own axis. Allows the rotor to make contact with the housing in a way that constantly changes the gas volumes inside it.

Housing

The Housing is the main body of a rotary engine, designed with an oval shape to maximise the displacement efficiency of the engine as the rotor spins. The edges of the rotor are in constant contact with the inner wall of the housing. Creating gas pockets that transition through the four sections of the combustion cycle: intake, compression, combustion, and exhaust. Spark plugs and fuel injectors are inserted directly into the wall of the housing. With channels on the outside that allow oil and coolant to pass through the system. This not only helps in maintaining the integrity of the rotor’s gas-tight seal but also in regulating the temperature within the engine.

Output Shaft

The final essential component, the Output Shaft, serves as the medium that transfers the energy generated from compression and combustion to the drivetrain, ultimately powering the wheels. This shaft is mounted with round lobes that maintain contact with the rotor, causing it to spin within the housing. The synchronized movement of this shaft with the rotor and housing not only showcases the elegant engineering behind rotary engines . But also their ability to maximize displacement and power output with their oval-shaped design, allowing for edges to be in constant contact with the inner wall, a testament to the genius behind the very concept of rotary engines.

Each of these components plays a critical role in the sense of work executed by a rotary engine. From the smooth spinning of the rotor to the robust containment by the housing. Down to the power delivery via the output shaft. Understanding them gives us a glimpse into the brilliant complexity that defines these engines, setting them apart in the world of automotive machinery.

Are There Any Benefits to Rotary Engines in Cars?

• Rotary Engines: Unique internal combustion engine variant featuring a triangular-shaped rotor that cycles through intake, compression, combustion, and exhaust within an oval housing.
• Conventional Piston Engines: Traditional engine design utilizing pistons moving up and down in cylinders to accomplish the combustion cycle steps.
• 1920s Onwards: The historical time frame marking the inception and development of rotary engines.
• Main Body & Oval Shape: Describes the distinctive design of rotary engines focused on maximizing displacement through an efficiently designed housing.
• Rotor Spin & Edges: Key functional aspects of rotary engines where the rotor spins, maintaining continuous contact with the engine’s inner wall, ensuring efficient combustion.
• Thermodynamic Efficiency: Concerns related to the rotary engine’s lower efficiency compared to piston engines, attributed to larger combustion chamber sizes and lower compression ratios.
• Smooth, Quiet Action: Advantages of rotary engines offering a smoother and quieter operation due to fewer moving parts and a design that reduces vibration.
• Counterweights & Rotary Housing: Elements added to the outer part of the rotary engine that help in damping vibration, contributing to the engine’s smoother performance on the road.
• Fewer Moving Parts: A feature that underlines the reliability, reduced maintenance, and the potential for lower operational costs of rotary engines over time.
• Stress & Strain on Parts: Rotary engines exhibit less wear and tear on internal components due to their unique single-direction movement, in contrast to the rapid reciprocal action of pistons in conventional engines.

Fascinating Rotary Cars – That Aren’t Mazda RXs

When discussing the revolution that rotary engines brought to the world of road-going cars, the narrative often centers around Mazda and its success story with models like the RX-7 and RX-8. However, the realm of rotary-powered cars extends far beyond these well-known icons. The Wankel rotary design, known for its small capacity and high specific output, has been a key drive behind several fascinating projects, capturing rotary fame even outside Mazda’s endeavors. As we take a trip down memory lane. let’s explore these marvels that aren’t Mazda RXs but are equally significant in the history of rotary engines.

Audi A1 e-tron concept

The Audi A1 e-tron concept marks an unlikely entry to this list and represents the most recent envision of hybrid drivetrain technology. Utilizing two electric motors and a compact 254cc Wankel engine, this concept was Audi’s bold step into the future of small cars, showcasing flexibility in engine swaps and a notable range-extender functionality. Despite its modest 60bhp always on tap, the A1 e-tron concept promised a 155 miles range, merging past rotary design principles with future electric drive aspirations.

1969 Mercedes-Benz C111

The 1969 Mercedes-Benz C111 was an experimental gullwing GT, serving as a test-bed for Wankel rotary engine technology. Despite its limited production run, the C111 with its mid-mounted triple-rotor Wankel producing 285PS. Became a definitive example of a desirable rotary supercar. Its appearance at the 1970 Geneva Salon propelled its status, though a series for the public never materialized. It remains a unique testimony to Mercedes’ experimentation with rotary design.

Mazda Cosmo (HB)

Mazda’s Cosmo marked the brand’s first venture into rotary-engined cars, eventually becoming its flagship. The HB Cosmo, in particular, though less desired than the JC or early versions, stands as a 1980s design icon. With outrageous interiors and pop-up headlights, it’s a pure piece of the decade’s aesthetic, albeit not the prettiest. Its technological prowess and retro charm make it a memorable Mazda not defined by the RX series.

NSU Ro 80

The NSU Ro 80 was a pioneer, introducing the Wankel engine to a larger audience beyond Audi Sport and western car enthusiasts. With a 995cc Comodo-built Wankel. It delivered a healthy 106bhp and featured a design well ahead of its time for a four-door saloon. It symbolizes the transitional phase of NSU’s rotary engine development. Later influencing Audi’s lineup, notably the A4, A5, A6, A7, and A8 models.

AMC Pacer

In the late ‘70s, AMC aimed to break free from its gas-guzzlers image by exploring a rotary engine prototype for the Pacer. Hindered by emissions regulations and engine supply issues. The project remained a “what could have been” story in North America’s automotive history. casting light on the broader industry’s flirtation with rotary design amidst changing fuel economy standards.

Citroen GS Birotor

The Citroen GS Birotor, or GZ, was a bold venture that combined Wankel rotors with hydropneumatic suspension for unmatched power delivery and comfort. However, its high price tag and the advent of the oil crisis led to its failure, with only 847 units reportedly sold. Citroen effectively erased this model from history, offering spare parts in acknowledgment of the few existing owners.

1970 Citroen M35

The 1970 Citroen M35 was an experimental two-door coupé, born from a joint venture with NSU. Aimed at offering a rotary engine within a vehicle based on the Ami 8, it was assembled in limited quantities and featured a hydraulic variable height suspension. Initially a pioneering project for rotary cars, it became a collector’s item, favored by clients prepared to pre-test these technologies.

Chevrolet Aerovette

The Chevrolet Aerometer was an absolute masterpiece of American design, showcasing a mid-engine, rotary-powered profile. Its journey through the 1970s saw various phases. From the Experimental Project 882 (XP-882) to incorporating a four-rotor engine and eventually being canceled. The oil crisis and changing GM priorities shelved what could have been a legendary entry into rotary cars’ history.

1985 AutoVAZ 2108 Lada Samara

The 1985 AutoVAZ 2108 Lada Samara stands as an unlikely but noteworthy Soviet-era exploration into rotary-engined models. Primarily used by official bodies like the KGB, it featured a twin-rotor VAZ 415 engine, highlighting the possibility of rotary engines running on low-octane fuel within the USSR. Despite its limited volume production and specialized usage, it marked Lada’s foray into rotary engine territory, albeit briefly.

In revisiting these models, it’s evident that Mazda’s venture into rotary engines was not a solitary journey but part of a broader exploration across the automotive industry. Each of these cars represents a unique chapter in the success story of rotary design. Transcending the familiar narrative centered around Mazda RXs and the 787B’s Le Mans victory. These projects collectively illustrate the versatile and innovative spirit inherent in rotary engine development. Leaving an indelible mark on automotive history.

Which Cars Have a Rotary Engine?

In the vast landscape of automotive engineering, the rotary engine carved its niche as a marvel of modern cars. Setting aside the drawbacks tied to economy and expense that often come with innovative manufacturing practices.

It’s a saga of resilience and invention, particularly championed by the Japanese car brand Mazda. Mazda’s pioneering spirit in the 1960s laid the groundwork for what would become a series of experimented successes that reshaped the way we perceive vehicle powertrains.

The 1967 Cosmo Coupé emerged as a beacon of efficiency and ultra-smooth performance. A stark contrast to the piston-powered engines that dominated the era. Then came the iconic RX-7 and RX-8, vehicles that not only celebrated the prowess of the rotary engine . But also underscored Mazda’s commitment to this technology.

Mazda’s journey didn’t pause with these models. In 2013, they launched a rotary version of the Mazda 2. And recently announced plans to build a new rotary engine that integrates with an electric motor as a range extender for hybrid-electric vehicles. This strategic move underlines the brand’s belief in the unit as a perfect match for hybrid cars. Touting it as a solution that delivers sound. Reliable performance akin to a standard piston engine but with the distinctive benefits of rotary engines. 

At the heart of this evolution is the anticipation of next-generation fuels like hydrogen. With rotary engines being uniquely adept due to their longer air intake period. This allows for more efficient mixing of air and fuel in higher quantities to be injected, ensuring the correct fuel-air mix, thereby improving efficiency and performance.

Mazda’s forefront innovation hints at a future where car brands might follow suit to address Emission Standard legislation. Embracing rotary engines for a new look in the 21st century. Such advancements make conversations about these engines not just a niche interest but a significant discourse in the automotive community. Whether through experiential tales shared in the Redox Club, insights on innovative fuel additives, or the potential of system cleaners.

 As someone who has seen the automotive world evolve. The continued exploration and reputed work in rotary engines is not just promising but exhilarating, offering a fresh perspective on how we evaluate car economy, expense, and manufacturing drawbacks. It makes one enjoy the article of progress and innovation, eager to like and see more rotary-engined cars on the road, fostering a conversation about future possibilities, alternatively to learn more about such intriguing topics, one can always visit the homepage today.

Conclusion

In conclusion, the saga of the rotary engine, with its illustrious history and distinct mechanical prowess, presents a fascinating chapter in automotive innovation, especially as we stand on the brink of its potential resurgence in the form of hybrid-electric vehicles. My journey as an automotive engineer has allowed me an intimate view into the workings of these engines, marveling at their efficient, elegant design that contrasts starkly with traditional piston-powered engines. 

Despite the challenges of high cost and environmental concerns that once nudged the rotary engine towards obsolescence. Companies like Mazda continue to champion its revival. They see in it a harmonious blend of old and new, where the lightweight, compact design of the rotary can contribute to more environmentally-friendly, fuel-efficient hybrid models. This anticipation of a comeback, integrating a technology considered to be a relic by some, into modern, next-generation fuel solutions. Is nothing short of exhilarating for automotive enthusiasts.

 It not only underscores the ever-evolving nature of vehicle engineering but also highlights a future . Where the rotary engine could redefine efficiency and performance in the automotive landscape. Such a future promises to reshape our perceptions of what cars can be. Fueled by the legacy of innovation that defines the rotary engine’s past and its potential path forward.

FAQs

Which car has a rotary engine?

Without the rotary engine, there would probably be no Mazda. And without Mazda, the rotary engine certainly wouldn’t have been in production for nearly 50 years. It was Mazda’s engineers who took Felix Wankel’s unique engine design concept to fruition, and commercial success, five decades ago this year.

Who uses a rotary engine?

Although rotary engines were mostly used in aircraft, a few cars and motorcycles were built with rotary engines.

Did Toyota make a rotary engine?

The Toyota rotary engine will be acting as a range extender for an upcoming electric vehicle. The vehicle, tentatively called the, “e-Palette Concept”, was on display in Las Vegas at Toyota’s booth. The concept car is being designed as a fleet vehicle, mainly for use as taxies, rental and deliveries.

What is an example of a rotary engine?

Rotary engines or Wankel engines are a type of internal combustion engine, most popularly used in the Mazda RX-7. Which converts heat from the combustion of a high pressure air/fuel mixture into useful work for the rest of the car.

Do all cars have rotary engines?

Very few modern cars have a rotary engine. Because of the drawbacks associated with their economy. As well as the relative expense of manufacturing them, most car makers have stuck to piston-powered engines. But not every one of them. Japanese car brand Mazda has experimented with rotary-engine cars since the 1960s.

Why is rotary engine banned?

Indeed, it has been suggested the noise led to the 787B being banned. However the truth is simply that it was the victim of the changes in regulation. At Le Mans, reliability is key. Mazda were confident in the reliability of their engine. And the 5 speed Porsche gearbox it was mated to was also known to be reliable.