Australia is an automotive goldmine. It really is. It’s not hard to draw comparisons to those Scandinavian countries we have familiarized you with over the last couple of years courtesy of Gatebil events, because Aussies and Vikings think very much alike. Both like cars – that’s sort of a given – both have an incurable addiction to power and speed, and to top it off, there’s always the need to reinvent oneself. This helps keep us all very entertained, at times amazed. It’s particularly the latter quality that comes into play with one of the few final cars I’ve been holding onto from last year’s World Time Attack Challenge.
This S15 Silvia may initially seem like the sort of project you would see come out of a well-founded tuning or race shop, but like a lot of the cars we feature from Gatebil, this was put together by its owners, Wayne and Andrew Sutton. Authenticity was very much at the core of this time attack build, with lots of inspiration being taken from the Silva that raced in the GT300 class of JGTC years back.
Being firm believers in attention to detail, this was really the only way they were ever going to tackle their S15 and that is a very good thing because this Silvia is nothing short of inspiring. Take the aero for example: every main body panel you see was custom shaped and made, because they knew that if they had to do this properly, no compromises were to be taken. Like all great builds, it all followed an evolution which began back when the car was first purchased by Wayne in 2005, while he was living in Japan. Back then the car was NA, and it stayed NA even after being shipped back to Australia and further developed. But then the need to be competitive in time attack brought on the unassailable move to forced induction. But more on the engine later on…
It was the body that made me instantly notice the car at WTAC last year; the clean lines, the lack of graphics to clutter up the flowing profile – it just looked so functional and meticulously put together. To achieve this look, Wayne and Andrew custom-molded the entire body, starting off up front with the widened bumper featuring a big gaping center air intake designed to supply just the right sort of airflow to the cooler cores hiding behind it. Additional aero touches were bolted on, like the carbon front spoiler that extends underneath the front section, as well as the pair of Voltex carbon canards to further aid in front downforce.
Dumping air quickly and efficiently from inside the engine bay is just as important as scooping it up in the first place and this is facilitated via the large V-shaped louvered openings on the First Molding carbon bonnet.
The GT-inspired fender design followed, gently blistered around the dummy headlights and extending into a squarely-profiled arch. Additional carbon fiber trims are added to help airflow over the front section while the fender itself creates a large opening as it meets the carbon doors, helping to flow as much air out of the wheel arches as possible.
The newfound width allows the Sutton brothers to run a big wheel and tire set-up, which at the time of shooting consisted of 10.5″-wide 18-inch RAYS Volk Racing CE28Ns shod with Advan A050s in the must-have 295/35R18 size that everyone runs now. Through the matte bronze spokes, it’s not hard to notice the red Endless brake package made up of six-pot calipers up front and four-pots at the rear, biting down on two-piece slotted rotors.
The flow of air around the profile of the car is taken advantage of by the custom side skirt design. Underneath the car, a carbon fiber floor works wonders at increasing downforce when travelling at the sort of speeds often reached at tracks like Sydney Motorsport Park.
It’s then over to the rear fenders, held in place with lightweight aluminium screws for easy removal. Here we have an even more aggressive widening; the sort of square shoulder line that you would expect to find on any purposely-built race car – in this case complementing the front end treatment beautifully.
It doesn’t take long to realize that a lot of thought and time was put into designing and creating the right sort of aero additions, but that is one observation that especially makes sense when you view the car from the rear. Lots of cutting of the rear bumper has been done, which along with the rear fender openings, helps cut down on drag that would otherwise create all sorts of problems with the flow of air under the car.
The one-off extended diffuser section is there to take over from the underfloor, helping to efficiently channel air out and use it to create additional downforce and eliminate nasty turbulence.
As we’ve learned in the past from posts we’ve done in collaboration with Andrew Brilliant, any aerodynamic addition always complements and affects another, and at the rear, the work done by the diffuser is joined by the massive amount of downforce that the Voltex wing generates. The wing supports extend down through the carbon trunk lid, transferring load directly onto the S15’s chassis.
I found this really interesting: as I was looking at the wing design, Wayne pointed out the little gap on the trunk lid right behind both of the wing stays. That’s how much the supports flex under full load, eating away at the carbon surface. Crazy stuff.
Add up all the little details and meticulous touches, and you have one of the most complete S15 time attack cars we’ve seen on Speedhunters.
The S15 was entered in the Pro Am Class at WTAC last year and with Andrew behind the wheel, it recorded a 1’31″832 which was good enough for second place. After having come fourth in 2011, this was a superb result and one they were very happy with.
This S15 was one of the very first cars in the world to wear the #WeHaveBoost sticker and it really couldn’t have been applied to a more suited car. Let me elaborate.#WeHaveBoost
You see, as I mentioned, the S15 was originally a SpecS model, which meant it came with the SR20DE version of the engine from the factory. Wayne continued to perfect the car in this guise up until 2011 when they decided to enter WTAC for the first time. It was at that point that a turbo was added (#WeHaveBoost!!), but it wasn’t so much a simple case of ‘let’s strap a blower to the little four-pot and see what happens’ sort of thing, but more something along the lines of ‘let’s start afresh’.
The SR was treated to a complete overhaul by JUN in Japan who rebuilt it from the ground up and fitted their 2.2 liter stroker kit. They paid extra special attention to the Nismo N2 head which was ported very much like a GT engine would have been ported back in the day. JUN 272 cams were added and the engine was all sealed up, creating a 9.1:1 compression ratio. A Precision 6466 twin scroll turbo followed next, mounted onto a 6 boost manifold and controlled by a pair of 38mm Turbosmart external wastegates. After being compressed and cooled in the HKS GT intercooler core, the intake charge is delivered into the four cylinders through the Hypertune throttle and plenum.
I thought the unpainted surface of the SR’s cam cover was a very nice fit to the whole overall character of the build. Fuelling is down to monstrous Bosch 2200cc/min injectors which have to spray copious amounts of E85 to match the thirst of the custom-built engine.
The way in which the same attention to detail is carried over into the engine bay is a joy to admire, and one detail I really liked was the placement of the piggy-back tanks of the Midori-built Aragosta suspension which the car rides on. These race-prepped dampers join fully adjustable Ikeya suspension arms as well as Sard adjustable front and rear sway bars, to allow the S15 the multitude of adjustment any focused track car of this caliber requires.
Unigroup Engineering took care of tuning the Autronic SM4 ECU, extracting 490kW at the rear wheels. To you and me that translates to 657hp at a boost setting of 35PSI, but to have a more manageable and reliable set-up, the brothers were running 27 PSI at WTAC which gives 577hp. All of that power is channelled to the rear Nismo carbon LSD via a Holinger six-speed sequential and an ACPT carbon propshaft.Excellence is in the details
Out on track this translates to close-to-instant gearshifts – something very important when every hundredth counts. Plus it allows the driver to concentrate on his line and just keeping control of the car. Driving on the very limit of grip and aerodynamics is a strain on the driver, so the less he or she has to do behind the wheel, the better.
The final piece to the puzzle was the chassis and the interior of the Silvia, and as you can see, it was as much about the details here as every other area of the build. Joining the rear portion of the roll cage that had been fabricated in Japan by Ishazaki-san of Faith Craft, the Sutton brothers took care of the front piping, calling in Mitch Ciaglia of Hypertune to take care of the welding. Seam welding and additional strengthening followed all around the shell, before the whole thing was painted by Neil Sutton, Wayne and Andrew’s father. Then followed the few but choice additions starting off with the Bride Zeta 3 bucket seat and Takata harnesses. If you haven’t noticed already, the Sutton brothers really appreciate the authentic JDM touch when selecting upgrades – something that further adds to the whole aura of the project.
The leather Nardi steering wheel is mounted onto a snap-off Works Bell boss to facilitate getting in and out of the deeply bolstered bucket seat, not to mention getting over the cage’s cross bars. Aside from a custom carbon fiber dashboard onto which the Racepack IQ3 data logger has been added, there isn’t much else to see.
It’s all beautifully minimalistic, with a few simple buttons and a kill switch for the electrics added to the carbon center console.
The execution is truly of the very highest standards, sort of making many other well-known time attack cars pale in comparison.
Simplicity is not an easy thing to obtain, especially when putting a complex thing like a time attack car together. But what the Sutton Brothers have managed to create with what started off as an NA street car in Japan all those years back, is quite outstanding and further cements Australia’s car scene as one of the most interesting out there.