Hiroki’s tuning shop, Sakamoto Engineering, has been a staple of the tuning community here in Japan for years. Based in Utsunomiya, Tochigi, Hiroki started his own shop after acquiring countless years of involvement in the racing industry. Our first introduction with Sakamoto Engineering was centered around the old shop demo car at Suzuka Circuit. To this day, the craftsmanship and execution on that RX7 has left an impression on me, and it still remains as my favorite FD in Japan, personally. Hiroki’s ability to fabricate a package of both performance and aesthetic that remain hidden under a veil of simplicity is one that is matched by few in the tuning world. To achieve the times that he set in that car was impressive considering the moderation in power and aero tuning it had at the time. You can read a feature of the FD in this article here.
It wasn’t long after that article was written that Hiroki abandoned development of the FD. Over the next few years, the shop turned its focus onto a handful of other projects including both customer cars, a GR86 entrusted to Hiroki by Apex’i for product developments, and his younger brothers red FD. In 2021, he decided that it was time for him to begin building another Sakamoto Engineering flagship car, and he eventually settled on the ZN6 platform. For a few years he campaigned the car to develop a solid baseline of the cars characteristics. A few notable modifications including a widebody Artisan Spirit kit, and a bolt on HKS turbocharger, provided him a platform worthy of testing. You can reference that version of the car in this article here. Earlier this year, the car was parked and work began to transform the ZN6 into a form worthy of the Sakamoto name.
Slowly but surely, the same approach that was used to build the FD is being executed on the new ZN6 build, and now that the chassis is in it’s final stages of completion, I wanted to catch up with Hiroki to get a better look at it. There are some parts of the car Hiroki does not yet want to make public, but I think we did a good job of showcasing the car through this video and the accompanying photos.
“The pursuit of speed is the most important aspect of racing, but when it comes to tuning, it is only part of the fun. However, when you pursue just a small part of it, and pursue it to its limits, there are new worlds that emerge.” – Hiroki Sakamoto
Schedule permitting, Hiroki hopes to have the car running by early next year. Once the chassis fabrication is complete, the old turbocharged FA20 will be used for testing. Once the car is dialed in both aerodynamically and suspension wise, Hiroki will swap in the new motor; a 2.2 liter FA series that he is building with HKS. Initially he is aiming for about 450 horsepower, which seems moderate given the seriousness of the build as a whole, but is very much in line with his tuning style. If you reference our Tsukuba ranking page you’ll note that in 2018 he ran a 54.217 in the FD making only 500 horsepower out of the 13B. That time still puts Hiroki in the top 20 fastest times at Tsukuba, and it was set over 5 years ago.
The massive front and rear aero are both custom pieces from Voltex based off of Hiroki’s specifications. The first thing most people would notice on the ZN6 is the massive 2000mm single element rear wing, which is currently mounted way below the roofline, in what appears to be almost a drag configuration. As cool as that looks, it most likely won’t be the final position, as the shop has developed a unique system of adjusting the wing height without needed additional stands. The front splitter is also from Voltex. A 3D design that is just as adjustable as the rear wing, leaving Hiroki with plenty of room for adaptation and tuning.
The car will be running Shibatire’s new 295 series slick, as a test bed, well as the tried and true Advan A050 GS. Eventually the car will be on a square set of 18×10.5j or 11j +15 or +22 wheels also made by Shiba Tire, but is currently seen on 18×9.5j +22 wheels as rollers. The final wheel size has yet to be determined by the manufacturer. The wheels developed and produced by Shiba Tire are currently being managed by AME. Super Now PCD100 to 114.3 spacers are currently being used, and will be used in the final setup as well. The ZN6 has been equipped with KW dampers and Ikeya Formula arms; two companies that Hiroki has worked extensively with over the years.
As mentioned earlier in the article, the ZN6 chassis overhaul is nearing completion after several months of some pretty serious modification. The original body work has all but been replaced with custom metal work. The firewall has been remade and pushed back several centimeters, resulting in a more centered weight distribution. This change means the seating position had to be pushed back as well, and a set of floor mounted pedals has been installed. The engine bay has been remade to structurally support the chassis on track and reduce overall weight. With these changes and reductions in bodywork, along with the assumed carbon roof, hood and trunk, Hiroki estimates that it may be possible to reduce the cars overall weight to less than 1,000kg. Although he will certify this after completion.
While there is still a ways to go in hitting the track, the progress so far is more than impressive, and exactly what we’d expect out of Sakamoto Engineering. Rest assured we’ll be following this build as it progresses and will be reporting back after initial testing.
Thank you to Hiroki and the Sakamoto Engineering staff.
Please enjoy the video and photos.
Thank you to Hiroki and the Sakamoto team for their time. Hoping to see