3-Rotor Turbo & NOS, 4-Rotor NA: Drag RX-7s Done 2 Ways

At last month’s Option x G-Works Super Drag Festival, two FC3S Mazda RX-7s caught my eye in the Central Circuit pits. While the pair share some similarities – including the fact that they were both down from Hokkaido – they’re quite different machines under their ultra-clean, white bodywork.

At a quick glance from a front-end view, the first car looked a lot like any other tuner-style FC3S we’d feature on Speedhunters. But as I got closer to the SWATT/Zeroyon Factory RX-7, the details you only find in a purpose-built drag car began to present themselves.

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Weld Racing wheels and Hoosier tyres – 29×11-inch slicks out back – check. Flat rear wing and parachute, check. Polycarbonate windows all around, check. 5-inch tachometer with shift light, check.

Compared to most of the other cars competing at the Super Drag Festival, the Mazda looked quite stock, but seeing the huge side-exit exhaust sprouting from the right front fender, I knew there was going to be something definitely not stock under the hood.

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The RX-7’s owner and driver, Akira Kato, was keen to show me what his FC RX-7 was packing, and it’s some serious rotary firepower. We’ll start with the Garrett GT4508R turbocharger (featuring an 80mm compressor inlet), with fist size for comparison. Given the size of the turbo, I was surprised to learn that it’s not even the biggest Garrett available; up to 106mm versions are available right off the shelf.

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The engine itself is a 3-rotor 20B from a JC Eunos Cosmo, but Kato-san has thrown a lot at it, including a whole of boost and a shot of nitrous oxide to get things moving. According to the team, the engine has a 9,200rpm redline and makes 950ps, which is more than four-and-a-half times what the RX-7 left the Mazda factory with. Yikes. 

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As a mostly stock chassis car running a Jerico transmission and R33 Nissan Skyline GT-R rear end, the RX-7 is no lightweight, but Kato-san has made good progress with the car and is banging on the 8-second door having run a best pass of 9.052 at 233km/h earlier in the year. That time is quick enough to claim the fastest rotary spot in the Japan Drag Championship’s ‘RWD Over 2.5L & 3-Rotor Engine’ class (fourth outright).

I can’t find any videos of the SWATT car running on the day at Central Circuit, but you can check out this video from a Motegi event earlier in the year to see and hear it in action.

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The other white RX-7 storming down Central Circuit’s straight a few weeks back is one of Japan’s most famous domestic drag cars owned by a true zeroyon OG. It’s been in Makato Watanabe’s hands since it was brand spanking new in 1986 and drag raced from day one, so I can’t decide which is the biggest legend – Watanabe-san or the Mazda. By now they would have surely formed some kind of symbiotic relationship, so they both deserve equally high praise.

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For the first 10 years of their relationship, the RX-7 dominated the Hokkaido street drag scene with an aggressive side-port 13B turbo setup. In the early 2000s, the car was converted to a full tube frame chassis, which Watanabe-san purchased by mail order from RJ Race Cars in the USA. The parts arrived, and, relieved that nothing was missing, Watanabe-san built a chassis table in his workshop and welded the frame together. Some modifications were required, but the RX-7 body panels fit.

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Over the years the car has been run with different engine setups and won many trophies, most earned on the now closed Sendai Hi-Land Raceway drag strip. Watanabe-san has also taken the car to Australia in the past, going heads-up with some of the quickest sport compact drag cars in the world at Willowbank Raceway during the Jamboree event.

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Today, the RX-7 is powered by a naturally aspirated 4-rotor engine pieced together by Yashiro Engineering. Tuned through a MoTeC M800 engine management system, the custom ‘YR26B’ produces 600ps.

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The 2022 Option x G-Works Super Drag Festival was a memorable event for Watanabe-san and his team. Not only did they set a new class record early on in the event with a 8.707-second pass at 247.42km/h, but on the very last run of the event they dropped their best ET to 8.559-seconds. How good is that?! You can watch footage of the record pass here.

I’ve got one more car from this event to share with you, and it’s a real blast from Japanese drag racing’s past. Look out for that soon.

Toby Thyer
Instagram _tobinsta_
tobythyer.co.uk

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1

One of the rotor's biggest surprises for me was how well IRL they drag... Given weight becomes a good traction friend in the higher speeds and the displacement is comparatively low even in 4 rotor spec. What tragic engineering... Mazda may have been wrong about BEV's but, they def weren't wrong about Rotaries

2

Another drag racing article, this one even cooler than the last. Never disappointing, always exciting and inventive cars/builders. Love it.

3

Both cars are awesome. Though I'm a little surprised, that the second one is N/A

4

I don't usually see a lot of drag RX-7 builds but it is a pleasant to see here at Japan's drag racing scene
I bet those rotary engine sound so heavenly going down the strip

5

Nice!

6

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7

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