The Mazda Cosmo Sport 110S was the world’s first dual-rotor rotary engine powered car. Its first prototype model was unveiled to the public at the Tokyo Motor Show in October 1963. The Mazda Cosmo Sport featured beautiful, futuristic proportions and exceptional driving performance. After the formal announcement of the Mazda Cosmo Sport, the engineers continued to work on quality and durability improvements to produce more refined performance before the production would begin in 1967.
Rotary engine development had begun at Mazda in 1961. However, the first years presented nothing but problems and setbacks. The most serious of which was the appearance of chatter marks on the inner walls of the rotor housing. After many trials, the engineers finally conquered this difficult problem by developing seals made of high-strength carbon infused with aluminum, and the Mazda rotary engine was born. After completion of the Miyoshi Proving Ground in June 1965, Mazda carried out continuous high-speed endurance tests, covering a total test-drive distance of 700,000 kilometres from the time development began.
The Mazda Cosmo Sport was eventually launched on May 30, 1967. It featured a 110 horsepower Type 10A engine (2 x 491cc) equipped with newly developed high-strength carbon-based apex seals. The intake system featured a side-port configuration coupled with a two-stage four-barrel carburetor, to keep combustion stable at all speeds. For the ignition system, each rotor was equipped with two spark plugs so that stable combustion could be maintained in cold and hot weather conditions alike, and on both highways and city streets. Mazda Cosmo Sport had a 4-speed manual gearbox. Powered by the 110 horsepower engine, Mazda Cosmo Sport could reach a top speed of 185 km/h and travel a quarter-mile in time of 16.3 seconds.
The L10A was in production only about a year before it was replaced by the L10B model in 1968. The L10B was slightly updated with a 5 speed gearbox, power assisted brakes and optional air conditioning. The wheel base was also lengthened by 150mm (5.9 inches). The overall weight of the car was up by 50kg to 990kg.
Type 10B engine was more powerful, thanks to revised port timing and carburetion. The air filter enclosure was also modified to have two intake tubes, the earlier Cosmo only had one. Although it was a bit heavier, the L10B offered a better performance with its 130 horsepower. The quarter mile time was 15.8 seconds.
Mazda Cosmo Sport 110S production ended in 1972. Only around 1500 cars were manufactured.