The hybrid and electric motors has been a big change in what motivates the modern car in a world where that has been resistant to change. Though the modern engine is definitely an evolved version of the unit developed by Karl Benz so long ago, they all have relied on more or less the same formula. A combination of gas and air fill a chamber with a piston in it that compresses the gas and air until a spark plug ignites it, pushing that cylinder down and another up to create power. The numbers have been shifted around from the number of cylinders to the size to how the gas and air gets in the cylinder to begin with, but the basic formula has remained the same. The piston engine has been the standard.

There has been challengers. In the sixties a handful of builders experimented with a turbine powered car where compressed air and gas turned a screw inside the engine similar to a jet engine. There was even a turbine car that competed at the Indianapolis 500 that almost won if it weren't for an unrelated part failure.

There is one other method for turning liquefied dinosaur into power that has made it into production championed by one manufacture in Japan. The manufacturer is Mazda and the engine is the Wankel rotary engine.

Related: Mazda RX9 Renders Spark Rotary Engine Return Rumors

Big Power in a Small Package

via youtube.com

The rotary engine, predictably enough, uses a series of rotors in place of cylinders. In the rotary engine the roughly triangular shaped rotor moves inside a chamber in an ellipse that compresses the air and gas before the spark plug ignites it, sending it spinning into its next compression and exhaust cycle. The rotor does a better job of managing the combustion and exhaust cycle in a smaller package.

Even better, just like pistons, rotors can be stacked up for even more power per rotation.

The big advantage the rotary engine gives is size. A rotary engine can get more power out of a smaller package. This contributes to the the most important ratio in going fast, power to weight. If the rotary engine can produce more power with less weight than that extra power means that much more.

The rotary engine delivers that in spades and managed to demonstrate that best when the Mazda 787B won the 1991 24 Hours of Le Mans being not only the first overall winner from Japan but also the first rotary engine to win the legendary endurance race.

If the rotary engine supplies more power with less weight, though, then why is Mazda the only one carrying the banner? Well, there are a few hitches.

Power at a Cost

The Mazda 787B is the first and only rotary to win Le Mans
via wikimedia.org

The rotary engine gets its power at higher revolution which carries with it a few problems in making the engine daily use friendly. They produce a high pitched and loud engine noise that has to be mitigated, but that's not the only problem. Faster rotations means more firing sequences and more firing sequences means more fuel being poured into the engine. While a turbo charged car might get bigger engine performance with smaller engine efficiency, the smaller rotary engine delivers bigger engine performance with almost no savings in mileage.

The other problem is that despite its power to weight advantage, it's not particularly efficient with the fuel it burns, making the engines dirty to operate. Even before climate change was a big issue driving countries to impose emission averages that only having an electric in your lineup could meet, the RX7's rotary engine struggled to meet emission standards and along with the Nissan Z cars and the Toyota Supra the RX7 left our shores.

The rotary returned in the RX8 but the combination proved too fussy for American buyers and while it had some initial success, it eventually faded.  Just like the RX7 before it, it couldn't meet growing emissions standards.

Mazda has been playing with a new RX7 concept and they've slapped their 'SkyActiv' 'clean' motor moniker on the rotary engine, but a production version that can meet modern standards has yet to manifest.

Next: Mazda Repurposes Rotary Engine As An EV Range Extender