Felix Wankel's rotary engine has been fascinating gearheads for decades. Even so, Wankels' engine has been generating more than its share of press recently, with some news sources speculating that the engine will be making a return as a compact range-extending generator in future plug-in hybrids from Audi and Mazda, who are even talking about a hydrogen-fueled rotary.
Despite decades of rotary-powered vehicles, though, it seems like a lot of people have misconceptions about the engine, which spins almost continuously as it takes air and fuel through the familiar "suck-squeeze-bang-blow" combustion cycle. Check out the diagram, below, to get a better sense of how a rotary works like a piston-engine ...
... do you get it now?
Don't worry if you don't. The short version is that rotary engines generate more power and torque - by far! - than similarly sized/similar displacement piston engines, and do so with much fewer moving parts, to boot.
As you can probably tell, I'm a big fan of rotary engines. As a fan, I've accumulated a wealth of useless opinions regarding rotary engined vehicles that I've decided to share with you in the form of a handy-dandy "buyer's guide" to rotary goodness. Enjoy!
The Best Rotary Engine Racecar
People will tell you that the best rotary-engined racecar was the Mazda 787B that won at LeMans. Those people are wrong, and have been mis-led by that car's single LeMans victory in 1991 and its prominence in Sony's GranTurismo racing games.
The correct answer is the 787B's replacement, the Mazda RX792P. The RX792P was named after Mazda's RX7 road car, the year it debuted (1992), and the designation "P" for "prototype", which was the class of racing it was built to compete in. The car hit the track just as Nissan, Jaguar, Peugeot, and other heavy-hitters pulled out of the world championship, leading to the series' cancellation (along with the cancellation of the All Japan Sports Prototype Championship). Without a global stage to play on, Mazda pulled financing, leaving only a few "shakedown runs" in America's IMSA series to tease us all with dreams of what might have been.
I'd be shocked if you could get one for less than six-figures today, but they're out there. If you want to go racing in a bad-a**, rotary-engined racecar, this is the one.
The Best Rotary Engine Racing Vehicle
Ho-ho! See what I did there? This isn't a car - it's a kart, and it will out-brake, out-turn, and out-accelerate just about anything on wheels below the kart's PBIR-measured 104 mph top speed.
The kart shown here won the nationals at Tulsa in 2007 during my tenure at RENNtech Karting. Powered by a 40+ hp Wankel rotary tuned by RENNtech's own Hartmut Feyhl, there was nothing even close to us at the flag. These karts zip to 60 faster than your car, can out-corner a motorcycle, and are used by Formula 1 drivers and the Mercedes/McLaren SLR driving instructors to keep them sharp, and they are always more fun than they think they're going to be. At nearly $20,000 (shipped), they Mercedes-branded asphalt karts aren't cheap, but throttling your vastly more talented competition with superior hardware never is.
The Best Rotary Engine Road Car
There are several reasons why the big manufacturers have stepped away from the rotary, and some of the biggest involve the engines' tendency to burn oil, fail emissions checks, then explode at high rpm. Beyond that, you simply won't get 3 million miles out of one ... maybe not even 1 million, regardless of how many times you re-hone the trochoid housing and change out the face/apex seals. Maybe future rotaries will be better, but the ones you'll be shopping are housed in Mazda RX7s and RX8s. Until cars start burning fuel with laserbeams, trust me on this one: skip it.
The Best Rotary Engine Road Car, If You Absolutely MUST Have One
If you're so enamored with rotary engines that you absolutely MUST have one in your road car ... but you want to maintain the illusion that rotary engines in road cars are a good idea, buy a Citroen M35. The French electrical gremlins and typically horrible build quality of the old Citroens will virtually guarantee that you never discover the practical failings of the rotary. You'll never keep it on the road long enough for the GS Birotor engine to fail!
Jalopnik recently featured the Citroen M35 on their own rotary engine list, and they summed up the car perfectly:
It tanked so hard that Citroen actually tried buying back and scrapping all the GS Birotors it could get its hands on so that they wouldn't be forced to maintain them, and nowadays very few of perhaps the weirdest of the weird Citroens exist.
The Best Rotary Engine Aircraft
If my assertions that rotary engines aren't particularly reliable haven't swayed you from wanting to put your life in the hands of a brittle apex seal at 30,000 ft. in a rotary-powered aircraft, then you're probably nuts. As a Grade-A nutter, you'll love the Moller Skycar! Powered by a number of high-output, low-emissions engines from Rotapower that pivot to provide V22 Osprey-style vertical takeoffs and landings, Moller has been promising to make good on the Baby Boomers' promise of flying cars for decades. We're all still waiting - maybe it'll be your purchase that makes the difference!
The Best Rotary Engine Motorcycle
Motorcycles are a totally different animal, in my opinion, than cars. Wrenching on your bike is part of owning it and earning it, and the almost religious attitudes many dedicated 2-wheel enthusiasts take towards bike maintenance is just what a rotary engine needs. The mid-70s Suzuki RE5, in my opinion, is the best example of the rotary motorcycle, especially considering the current wave of interest in mid-70s UJM "standards" from would-be cafe racers, nostalgic Gen-X ers, and trendy hipsters. The RE5 has all the positive qualities of the - let's say the Honda CX500, along the added weird/cool "x" factor afforded it by its gonzo powerplant.
If you have the means (and if your Google-fu is strong enough to source engine parts forged from unobtanium), you should definitely pick one up.
The Best Rotary Thing You Can Buy, Period
Powered by the same 40+ hp Aixro engine as that sexy RENNtech Mercedes go-kart up near the top of this list, the Stihl Hotsaw competition chainsaw can rip through any damned thing it pleases in seconds, and it can do so on gasoline, ethanol, high-proof moonshine, or just about any other hot, burny liquid. Despite the saw's German origins, watching this video makes me scream "F*** YEAH, 'MURICA!!" every time I see it.