For Yoshiya Yajima, only one path has ever seemed straight and true – ultimately, it turned out to be an elliptical one. “Ever since I was a child, my hobby has been cars and mechanical engineering,” says Yajima, the owner of NepTune Speed, a California-based repair workshop and tuning house for Japanese cars that specialises in Mazdas and rotary engines.

For man and machine, that path began in Japan. Working as a control systems engineer for a sheet metal manufacturer led Yajima to start modifying his car. “I enjoyed making parts for it using the company’s machines,” he says. When he was transferred to the United States in 1996, he bought a 1991 Mazda RX-7 convertible, inspired by a friend’s car back in Japan: “The appeal of the rotary engine is its unique sound, like a two-stroke, and the feeling of high-revving rotation.”

Learning to service and rebuild it led him to open NepTune Speed in Huntington Beach in 2006. It’s now a respected fixture on the lively California rotary scene, especially for RX-7s and RX-8s. “The climate here keeps cars in good condition, and many 1970s to 1990s rotary cars gather here, including for the annual SevenStock event.”

The 56-year-old is on a lifetime mission to extend the lives of aging rotaries by perfecting the basics – but loves maximising their sporting potential, too, often with a turbo. He’s even built a 320bhp Bridgeport engine for his own car. “I’m looking forward to Mazda releasing more advanced hybrid rotary engine cars,” he says. “I hope that rotary engines will be used for a long time.”

A shared love of Japanese cars brought John van ’t Hoff and Midas van der Ploeg together – and Rotors & Pistons (R&P) Performance was born just a few weeks later in 2017. The friends set it up initially as a space to work on their own hobby cars. Army engineer van der Ploeg, now 28, had a Mazda RX-8, his first-ever car; while van ’t Hoff, 34, with experience in sales at car dealerships, had owned a wide range. Both were handy enough at fixing and tuning cars that they decided to make a business of it.

Based in Zuid-Beijerland, south of Rotterdam, R&P Performance operates two evenings a week, and has become popular with people wanting to customise their rotary engine builds. “The rotary engine has great capabilities,” says van ’t Hoff. “As much as possible, we want to keep rotaries on the road and, of course, make our customers happy.”

Some of their more extreme customer projects have seen them overhaul virtually every inch of a car, and they enjoy getting elbow-deep in the technology. “We love to be different, and that’s exactly what rotaries are,” enthuses van ’t Hoff about Mazda’s rotary legacy. “Our favourite car is the RX-7 FD, which has the great possibilities to tune. And the Mazda 787B’s engine has one of the best sounds a car has ever made.” This is why the notion of a new generation of rotary technology from Mazda excites them: “It will keep the rotary spirit alive.”

The occasional distinctive throaty hum offers a clue to the treasure trove tucked away among the quiet backstreets of Thomastown. Known for its high-performance rebuilds and stunning race mods, Promaz Automotive is a mere half an hour from Melbourne’s city centre and is run by rotary specialist Simon Ioannou.

Ioannou, 50, grew up drag-racing with his dad at the local track, and was an apprentice mechanic in his teens. The sound of rotary engines reeled him in and their high-revving smoothness had him hooked. Experimenting with his own 1974 Mazda RX-3 eventually led to a stint at a rotary garage, before he started Promaz in 1999.

The expansive workshop is fully kitted out, with facilities spanning rotary plate machining, engine balancing, custom fabrication, and two dynos to measure results. And what results they are: from a customer’s gleaming RX-7 FB all the way to Ioannou’s own ProRX-8 – a storming 1,600hp RX-8, which he enters in Pro Street drag race events.

The family legacy has continued into another generation: the nine-strong Promaz team, with Ioannou’s wife in back-office operations, now includes 18-year-old daughter Olivia as a machinist in the workshop. He credits Promaz’s success to “passion, giving the customer what they want, and going above and beyond”. He adds: “We’re always trying to push boundaries. If you push, you break things and you learn. If you’re not always challenging yourself, you’re not progressing.”

Mazda’s rotary renewal resonates with Ioannou’s constant drive for improvement. “A hybrid rotary is a great idea,” he says. “You get the best of both worlds – meeting emissions to go with the times, while keeping the rotary engine alive.”