Jay Leno provides a deep dive into the rotary engine

The rotary engine has had the greatest impact on Mazda sports cars, but the recent episode "Jay Leno's Garage" focuses on the early history of Rotary.

Before the rotary engine was popularized by Mazda, it was produced by the German automaker NSU (the predecessor of Audi). Launched in 1964, the NSU Spider was launched 110 years before Mazda launched its first rotary car, the Cosmo 3S, in 1964.1 Of these early NSU rotary cars are now part of Jay Leno's collection.

The rotary engine was invented by German engineer Felix Wankel and subsequently licensed by a car manufacturer. It got its name due to the fact that instead of pressing the piston, the energy from the combustion of fuel and oxygen is used to rotate the rotor (or 2, as in the case of later Mazda engines).

The rotor has a triangular shape, but is attached to an almost round body. The triangular corners are designed to fit snugly to the body (which, as it turned out, is not easy for engineers to achieve), allowing the open space on the sides to function as a combustion chamber. The mixture of fuel and air (ignitable only from 1 spark plug in the NSU) is pressed against the side surface of the rotor and rotates.

The advantages of the rotary engine were smooth operation and compact dimensions. The NSU Spider engine is so small that it is located under the rear luggage compartment, which helps to complement this convertible with a regular trunk and small dimensions.The air intake is located on the rear trunk lid; air is directed to the engine through the trunk pipe.

Disadvantages included higher oil consumption compared to conventional piston engines and a tendency to self-destructive rotation.The NSU can easily rotate up to 8000 rpm, but this will cause the seal on the rotor to wear out. There is a green zone on the tachometer that ends at about 5,500 rpm, which encourages more conservative driving behavior.

The NSU Spider was also quite expensive at the time. That was in 1964, when it cost about 3,500 pounds, more than any other small sports car like the MGB. The engine power was 54 horsepower, and it was transmitted only to the rear wheels via a 4-speed manual transmission. Despite the Spider's curb weight of about 1,500 pounds, it was created for driving that requires a little patience.

After the production of a rotary sedan called the r080, NSU was acquired by Volkswagen Group in the late 1960s and became Audi.

Rotary engines survived, General Motors and Mercedes-Benz experimented with them in the 1970s, and Mazda made them a permanent part of its line, mainly RX-7 and RX-8 sports cars. The Mazda 787B, equipped with a rotary engine, was the first Japanese car to win the 24 Hours of Le Mans race in 1991, but production of the Mazda Rotary ended in 2012.

Mazda announced the return of the rotary engine earlier this year, but not as an expansion of the lineup for the new version of the MX-30 R-EV electric crossover. While the MX-30R-EV won't be coming to the U.S., Mazda unveiled an electric rotary concept known as the iconic SP at the 2023 Tokyo Motor Show. This should keep hope alive for the return of rotary sports cars.