Is August 13th marked on your calendar? If you’re a fan of the Wankel rotary engine – or any sports car powered by a Wankel rotary engine (we’re looking at you, RX-7 fans), it should be. Dr. Felix Heinrich Wankel was born on August 13, 1902, in Lahr, Germany.
Although Wankel passed away in late 1988, today would have marked his 110th birthday. As such, we’ve rounded up 11 of our favorite Wankel-powered vehicles ever built.
We previously heralded the Mazda Cosmo Sport 110S as “the world’s first car with a truly viable rotary engine” thanks to its twin-rotor engine. It was powered by a tiny 982-cc unit that produced 110 hp, revved to a 7000 rpm redline, and was mated to a four-speed manual transmission. Although prototypes were shown as early as 1963, full-scale production didn’t commence until 1967.
It wasn’t just the engine that set the Cosmo apart from the rest of the late-1960s and early 1970s automotive landscape – its styling was right in line with the futurism from The Jetsons. The body looks long with rounded haunches (and it got longer in 1958 with a 5.9-inch wheelbase stretch) and the greenhouse seems to bubble up on top of the rest of the flat body; however, the Cosmo was actually quite small, and is dwarfed by today’s MX-5 Miata. Just 1519 Cosmos were built from 1967 to 1972, and all of them were right-hand drive.
The Ro80 wasn’t the first NSU vehicle to make use of Wankel’s design (that honor goes to the homely Prinz-based Spider), but it was certainly the most ambitious. Slick, aero-friendly exterior styling? Check. Four-wheel-disc brakes? Check. Three-speed semi-automatic gearbox? Check. A 995-cc, two-rotor Wankel engine? Of course. Sadly, though the car showed tremendous promise (it was named European Car of the Year in 1968), reliability issues – largely surrounding rotor tip seals – quickly damaged its reputation. NSU was absorbed by Volkswagen (and Audi) in 1969, and the Ro80 was left to soldier on until 1977. Only 47,400 cars were built.
Citroen’s Ami was already an odd and oddly-shaped vehicle, but in typical French fashion, Citroen found a way to make it even more unusual. The M35, which debuted in 1969, looked like a two-door Ami fastback, but what was truly ungainly lurked underhood. In lieu of the standard air-cooled flat-twin shared with the homely 2CV, the M35 used a new, 995-cc, single-rotor Wankel engine. As an extra bonus, a hydropneumatic suspension – much like that used in the famed DS – is also installed. Citroen hoped to sell 500 examples, but ultimately wound up selling only 267, all to brand loyalists who allowed the company to keep tabs on the cars’ reliability and performance in the real world. The positive feedback prompted Citroen to offer the larger GS with a two-rotor Wankel in 1973, but slow sales — due in part by the engine’s thirst for fuel during the OPEC embargo — prompted the company to scrap the Birotor by 1975. Only 873 examples were built, and few exist today.
If you’re going to dabble with new technologies, why not do so with style? That seemed to be the line of thought behind Mercedes-Benz’s series of C111 experimental: although they primarily allowed the automaker to dabble with Wankel engines and composite bodywork, they also allowed the company to toy with the idea of a shapely rear-engine gulling sports coupe – and, subsequently, toy with car enthusiasts’ emotions at auto shows the world over.
The C111/1, which first debuted in 1969, made use of a 1.8-liter, fuel-injected three-rotor Wankel. Benz claimed the engine put out 280 hp, and that the C111 could spring from 0-62 mph in five seconds before hitting a top end of 170 mph. The C111/2, which debuted in 1970, boasted sleeker styling, a longer wheelbase, a revised rear suspension, and a much more powerful motor. A 350-hp, 2.4-liter, four-rotor Wankel replaced the old three-rotor, and allowed the /2 to hit a top speed of 185 mph. Daimler’s foray into Wankels was killed after 1973, but one of the /2 cars was dusted off in 1975, fitted with a diesel engine, and sparked a new wave of powertrain research at Mercedes-Benz.
Mercedes wasn’t the only company dreaming up sexy, plastic-bodied, Wankel-powered sports car prototypes. Mazda showed its variation on the theme – the RX-500 – at the 1970 Tokyo Motor Show. Although it looked something like a Can-Am car crossed punctuated with a Kamm tail, the car wasn’t quite as mechanically wild. The two-rotor 10A – borrowed from a race-spec Familia – was allegedly tuned to produce close to 250 hp, which was enough power to move the 1800-lb car to speeds in excess of 125 mph. The car was squirreled away in Mazda’s car collection for decades, but was restored in time for it to appear at the 2009 Tokyo Motor Show.
While it may never have actually made it past the concept stage, Chevrolet’s Four-Rotor Corvette is one of the only American cars to have a Wankel engine under the hood and had one of the most impressive engines to ever be found in a car wearing the gilded bow tie. That four-rotor engine was also the largest Wankel rotary ever installed in a car (displacement rang in at a whopping 9.6 liters) and it was mid-mounted for better handling and weight distribution.
The radical thought process that birthed the Four-Rotor Corvette didn’t end with the powertrain – after the four-rotor was replaced with a conventional 5.7-liter V-8, the car gained the nickname of the “Aerovette” thanks to its space-age exterior design. The slippery sports car scored a low Cd of just 0.325 thanks to a wind-tunnel-honed body and a pain of bi-folding gullwing doors helped up the science fiction factor to new heights.
The 1970′s were a good time for rotary engines. Mazda had its RX-7, Chevrolet had shown a rotary-powered Corvette concept, and Suzuki had a Wankel-engined motorcycle. Wait, what? Yes, from 1974 to 1977 the Suzuki RE5 utilized a 487 cc rotary engine that had been licensed from German automaker NSU. Suzuki also had Italian designer Giorgetto Giugiaro play up the rotary’s design by housing the gauges and taillight in cylindrical shapes, although changed the design to less daring one later on to make it look more like the company’s flagship GT750. (The fact that the original design was only available in two bright hues probably didn’t help either.)
Despite licensing the engine from NSU, Suzuki poured much of its own research and development money into the RE5′s rotary mill. The company actually holds some 20 patents for different parts of the engine, including on the engine’s subsystems. The Wankel was less than ideal for a motorcycle, however, as it had high fuel consumption and generated a lot of heat, necessitating the use of various systems for cooling.
The 787B, a Group C Le Mans racer, was powered by a 2.6-liter, four-rotor rotary engine, which reportedly made 700 hp at an astronomical (and loud) 9000 rpm. Mounted in the middle of an 1831-lb chassis and mated to a five-speed manual transmission, the engine was but one of the 787B’s distinctive features. The others were the car’s crazy orange-and-green color scheme, and its high-pitched, incredibly loud exhaust note.
Color schemes and screaming engines aside, the 787B made history in 1991 by winning its class (thereby winning the overall race) in the 24 Hours of Le Mans, becoming the first Japanese car and the first rotary-engined car to do so. Both records stand to this day. While Japanese companies keep trying to knock that first record off, specifically Toyota’s TS030 Hybrid, the second may stand forever: Le Mans banned the rotary engine in 2012.
A sequential turbocharger system uses two turbochargers: one turbo which spins up when an engine is at lower RPM, and one which provides optimal boost once the engine is spinning faster. The result is good amounts of boost (and power) at both low and high-rpm situations. The first-ever sequential turbocharger system to export from Japan was attached to a 1.3-liter rotary engine, which was found under the hood of the third-generation Mazda RX-7.
The results were nothing short of awesome: the 1.3-liter Wankel made 252 hp, which calculates out to an astonishing 193.8 hp/liter. That engine was coupled to a 2830-pound body (with a perfect 50-50 weight distribution), and as a result the RX-7 is still regarded as one of the best sports cars ever made. Mazda went on to produce almost 69,000 units between 1992 and 2002, although American buyers could only purchase the car between 1992 and 1995.
It’s unsurprising that Mazda – the car company that has most embraced the rotary engine – would have a concept car make this list. The RX-01 debuted in 1995 at the Tokyo Motor Show and packed Mazda’s then-next-generation version of its 1.3-liter Wankel engine with a five-speed manual. When the RX-01 made its debut, many guessed that it would preview the next-generation RX-7, which has been pulled from the North American market that year.
The RX-01 used a 2+2 seating layout and wild styling that included touches like a floating front bumper. But most importantly, the RX-01 was the first appearance of Mazda’s 13B-MSP rotary engine that used side-housing-mounted exhaust ports – a design feature that would help set the basis for the RENESIS engine found later in the RX-8. Pity the nifty front spoiler, formed in part by placing the RX-0 as far aftwards as possible, never became reality.
Unlike a piston engine, a Wankel engine spins–literally. This crankshaft-less design lends itself very well to applications like generators, where the engine can be directly mounted to the generator, turning the generator’s turbine or rotor.
Which is where Audi comes in: its A1 e-tron (which is still a concept) is powered primarily by an electric motor, which can putter the A1 around town up to 30 miles. But the A1′s kicker is a 0.25-liter Wankel engine that powers a 20-hp generator. With just 3.2 gallons of gas on board, the A1 has a total combined range of 155 miles, a peak output of 101 hp, and a theoretical mpg rating of 123.8 (on the EU cycle).
We can’t help but find it a little ironic that Audi’s futuristic drivetrain vision also employs a piece of its NSU history.
-By Evan McCausland, Donny Nordlicht, and Ben Timmins