Rotary Dreams: A Sporting Triangle



Enthusiasts familiar with Mazda know that the brand is most famous for bringing the wild and underappreciated Wankel engine to the masses. What you may not know is how that all came to be.

The humble, Hiroshima automaker has always been known to push the envelope and single-handedly brought the Rotary engine into the mainstream. We want to take a moment to turn back the hands of time to honour the sports car that helped skyrocket that rotary appeal and make this silly little engine, that sounds like a bunch of angry bees, synonymous with the brand itself.



The Mazda RX-7 is the most well-known rotary sports car in the world, and the first-generation "SA22C/FB" could be fitted with the famous 13B twin-rotor engine. The 13B has had many variations over the years and has been the base of every future rotary engine that the Hiroshima brand has produced since 1972. Initial cars that carried the new powerplant were badged with "AP" for advanced propulsion compared to their piston-powered counterparts. Unfortunately, this unique name was dropped when the RX-7 came into existence, replacing the RX-3 that came before it.


The 13B is a two-rotor Wankel engine. Each rotor is sealed in its oval shaped housing and is separated in the engine block assembly. The rotor has a distinct three-sided shape similar to the Reuleaux triangle with a pocket cut into each of the faces for compression and combustion. Seals are affixed to each of the three apexes to contain both as well as scrape oil from housing surfaces (and keep the rotor from rubbing on it). The rotor rides on an eccentric toothed shaft through its center, which acts similarly to a crankshaft in a piston engine. The Wankel Rotary is unique in the way that it can complete three cycles of combustion per rotation (as opposed to two from a four-stroke piston engine) and can operate at a much higher speed than that of a conventional engine while maintaining impressive smoothness.



Unfortunately, the 13B would not be available until the Series 3 update in 1984. The RX-7 was already valued as a world-class sports car, winning at Daytona and many other circuits in the IMSA GTU (Grand Touring Under 2.5L) Championship, but this new engine cemented its capabilities.

The FB RX-7 and 13B would be the first Japanese car with a powerplant not produced in Europe or America to complete the famed 24 Hours of Le Mans, a precursor to the legendary 787B winning a decade later. Known as the 13B-RESI (rotary engine super injection), this two-rotor engine featured Bosch port fuel injection and a unique intake manifold that manipulated air flow resonance. The wild little engine produced 135hp and 133lb/ft of torque, pushing the compact coupe to a 200km/h (124mph) top speed.



The FB was slated to be replaced by a new generation of RX-7 to bring Mazdas' sports car into a more modern time. In 1986, The FC debuted with updated styling and a significantly updated powertrain. Some compared the new RX-7 to the Porsche 924 and later 944 as there were many similar design cues, but this was not by chance. North America was one of the largest automobile markets, and the 944 was a trendy sports car at the time.

Akio Uchiyama, the FC project leader, set the Porsche as a benchmark and aimed for it to be bested. Not to be disappointing, The FC3S was available with two new versions of the 13B, the 13B-DEI, and 13B-T (for turbocharged). The engines produced 146-200hp and 138-196lb/ft of torque respectively, significantly improving performance over the FB despite its hefty increase in overall weight. The FC continued the RX-7s dominance in the GTU class, winning the championship every year it was in production (1986-1991).



The Mazda RX-7 now goes down in history as one of the most winningest automobile nameplates on the planet powered by a non-piston engine, and that's what all the buzz is about.



-Team 604

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