HKS has done a very good job of keeping this one quiet! I’ve heard it said so many times: ‘Why doesn’t HKS bring out the CT230R again and try and fend off Under Suzuki’s continual resetting of Tsukuba record?’ Well, the HKS team have been observing things in the background it seems, noting how aero technology has evolved and deciding when the right time to jump in was going to be. And after much R&D and work during the course of 2016, this is what the legendary Japanese tuner has come up with. It’s called the HKS GTS800.
If you’ve been following Under Suzuki’s attempts at Tsukuba, you will no doubt instantly assume that this car must be built for lap times in the 40-second range – and you’d be right. It just boggles my mind how far times have dropped at Tsukuba since the first times I headed out there in the early 2000s for Super Battle events. A 59-second lap and you and your car were seen as gods; a 57-second lap and you’d be on par with the Mine’s BNR34. The Cyber Evo and the M-Sport GT-R then came, dropping times into the 55-second zone, before Pan Speed and Revolution brought the rotary noise and dropped that down another second. Then, in 2007, HKS put an end to it all with a 53.589 Racing Performer CT230R before the rumored million-dollar project was retired.
A decade has passed since then, and this new Toyota 86-based time attack build was the last big project Hasegawa-san, the late president of HKS, approved before he passed away. Quite simply, the Tsukuba record has to be won back and nothing can be left to chance.
This car represents a whole new level of time attack car for HKS, and while the team took care of the mechanicals, the aerodynamics side of things was left to someone who knows a thing or two about putting together a winning package, namely Andrew Brilliant of AMB Aero.
HKS kindly allowed me to check out the car even before the Japanese media, and as this story goes live on Speedhunters the first presentation on the car will have just wrapped up at HKS Premium Day. I was here yesterday when the car was unloaded, so a huge thank you must be extended to the guys at HKS for allowing us this exclusive sneak peek.
There is a lot of secrecy still surrounding this project, but plenty we’re able to talk about, starting with the aero.
Generally speaking, conventional front wings generate downforce at the expense of drag, but with years of development and fine tuning, that’s been remedied. The design here has been refined to eliminate all the drag while making lots of downforce, but at the same time reduce any further drag.
It’s a little confusing, but just take it as a new generation of aero management. Of course, the vast exterior of the 86 was made by HKS in-house using dry carbon fiber.
I was blown away by the tolerances; the panel gaps are right on par with the Lexus LC500 GT500 race car I spotlighted at Tokyo Auto Salon.
What may possibly become a game changer are these AMB Design ‘Infiniti Wings.’ While we’ll find out exactly how they work in an interview I’ll be doing with Andrew Brilliant, they’re effectively an added element to the wing design that help boost lateral downforce. The whole wing and bumper package has been designed and sculpted to channel air in the corners towards them, helping them do their job. Like I said, this is next level stuff!
And compared to some of the wildest time attack cars we’ve seen in Japan and around the world, the HKS GTS800 looks remarkably clean. The final body shape is more flowing and smoother all over, hinting that downforce is being generated in a more efficient way. Gone are the days of multiple winglets, spoilers, louvers and outlets to ruin a car’s overall look.
This is also the first time attack car in Japan to run carbon discs. The setup comes courtesy of Endless and features beefy 6-pot calipers in the front and 4-pot calipers at the rear.
Just like on Under Suzuki’s S15, the exhaust system exits out of the side of the passenger door.
Wild Aero, Pleasing Design
But let’s continue our tour around the car…
If rear wing size directly correlates to the amount of front downforce able to be generated, the GTS800 must be pushing those front wheels right through the tarmac! HKS has floated the number 3 ton’s worth.
The massive triple-element wing along with the integrated trunk spoiler work in synergy to interact with the underbody, developing downforce and stability at the rear end.
This is a bit of an exaggerated wide angle, but you get the picture. At speed, all that force pushes down on 18×11-inch Advan GT wheels shod in 295/35R18 Yokohama Advan A050 semi-slicks at all four corners. One-off HKS dampers with ridiculously high spring rates to counteract the effect of the downforce are employed, and each hub is suspended by custom double wishbone suspension arms.
The roof, along with the panels that replaces the rear and quarter windows are also made from thin and very light carbon fiber, and are all secured in place with spring-loaded DZUS fasteners.
This is a good angle to gauge just how much wider the rear fenders increase the 86’s dimensions, but the most dramatic part of the rear end have to be the massive tunnels that manage and make optimal use of under-car airflow.
This is the first time a modern day time attack car of this caliber has remained so faithful to the original car it’s based on. It’s almost as if the aero has been designed in an organic way.
Looking inside, I noticed how only the top half of the doors actually open, a byproduct of the sill having been boxed and lifted up, not to mention all the chassis strengthening that’s been carried out. This is pretty much standard practice on Super GT cars.
Nobuteru ‘NOB’ Taniguchi, who of course will be doing the driving, hasn’t really got much to distract him. There’s a Nardi steering wheel, the AiM digital display and a brake bias adjuster.
And he sits in a lightweight Bride seat, which was made especially for this project.
The center console is where the switch panel lives, as well as the cut-out switch for the electrics. Seeing the cabin is sealed off right behind the driver, the carbon fiber partion doubles up as a nice location to mount the HKS F-CON V Pro engine management system.
The pedal box has been set as far back as possible in the somewhat cramped interior, and in doing so helping to provide the optimum driving position for Taniguchi.
Here’s a wider shot of it all.
The inverted bowl-like contraption on the fuel tank is there to seal off the fuel filler, a curious addition that Andrew Brilliant told me instantly reminded him of R2D2 in an X-wing fighter. Maybe it’s meant to be Taniguchi’s co-pilot?!
Under The Hood
So what powers something that’s been built to rewrite the Tsukuba lap record?
Well, a quick look at the front air dam and the opening in the hood obviously hints at forced induction. It would have to be boosted obviously; big power is required to lap Tsukuba as fast as this car has to with all that aero pushing it down to the ground.
And in true HKS philosophy you won’t find an engine swap – that would have been too easy. What you will find is one of the most modified 4U-GSE/FA20 engines every created. It’s been stroked to 2.5L, dry-sumped and dropped down and as far back in the chassis as it possibly could be.
That’s opened up space to allow the intercooler to sit flat to make full use of air that’s directed to it through the complex inner shroud, which on its lower section also houses the radiator.
The piping is extremely short, meaning the HKS supercharger which generates the boost doesn’t have to fill up an overly large volume of pipework to get the intake charge moving.
There are two HKS blow-off valves on the intake end tank…
…And another two on the s-pipe that feeds the intake plenum. It’s a curious modification, and one that probably hints at the speed the supercharger is able to deliver that boost.
There is no other information on the engine right now, but as the name of the car suggests, the ‘800’ in GTS800 has everything to do with the power figure the team is shooting for.
For the time being we’ll just have to be content with having seen the car in all its visual glory, but you can be sure Speedhunters will be heading out to Tsukuba for HKS’s first series of tests with the car. In the process we’ll find out more about what makes the GT800 one of the most advanced racing machine that Japan’s biggest tuning company has ever built.
Dino Dalle Carbonare