Bust out the Depends(tm) adult underwear because this Silvia is playing for keeps. The well-crafted speed demon embodies the "aim high" philosophy of Kazama Auto Service in Kasugabe-City, Saitama Japan. By definition, a time attack car is a purpose-built vehicle but Kazama narrowed its focus with laser-like precision when it created this S15 Silvia specifically for battle at Japan's famed Tsukuba circuit. The bull's eye? Generate a laptime of less than 60 seconds with only two liters of displacement under the hood. The Silvia is familiar territory for the Kazama crew as the company campaigns an S15 in the D1 Grand Prix drift series. Only a slight alteration in mindset was needed, namely, tune for grip instead of slip.
Kazama produces its own lineup of trick suspension components designed to allow the suspension to contort like a Cirque du Soleil performer. At the core of the Kazama line is adjustability, the over-adjustability of toe-in, camber, ride-height and the often-overlooked steering needed to maneuver sideways at 60 mph. The Tsukuba Special runs a Kazama pillow tension rod that replaces the stock rubber bushing with a solid spherical ball end that enhances rigidity. Custom control arms add strength and lightness to the suspension while a Kazama toe control arm allows complete adjustment of the Nissan's toe setting, which enhances its turn-in response. Tanabe Sustec Pro Seven coilovers are the centerpiece of the set-up and are used with the Tanabe Electronic Active Suspension (TEAS) that allows programmed adjustments of damping characteristics based on entry and exit speeds and other parameters.
Response is only part of the picture. You need superior mechanical grip, braking power and straightaway speed to put together a sub-minute lap at the famed Tsukuba circuit. Mechanical grip comes from Goodyear rubber, with compound selection being dictated by track conditions. The car runs a staggered set up with 17s in front and 18s in back, all wrapped around Gram Light wheels. Stopping power has been addressed with six-piston Endless calipers and mondo-sized rotors up front and a Brembo upgrade out back.
To close the deal, a time attacker needs bodacious boost screaming though a bulletproof powerplant. The Silvia is blessed with one of the all-time great turbo four engines: the SR20DET. Internally, the stout SR was readied for boost abuse with only 86mm HKS pistons, the rods were deemed up to the challenge. The goal in mind was around the 500 horsepower range. With that number in mind and the high engine speeds that the engine will endure the crank was dynamic balanced.
The pressure player is an HKS GT-series 3037S turbo. As with all GT series offerings, the 3037S features a full ball bearing center cartridge that allows the selection of a turbo that provides a bit more top without hurting response. The compressor housing checks in with a .60 A/R, which is the norm in the GT line.
On the hot side the turbine rotor is an 84-trim wheel with a 55mm exducer. Kazama Auto Service fabricated its own header to mount the GT3037S and enlisted a Blitz intercooler and intake piping to increase the density load of the incoming charge air.
The big SR20 idiosyncrasy is in the valvetrain. For big power in a serious performance SR20DET, high-lift cams are much-needed allies. On the street at 'reasonable' engine speed most SR20s are good to go with a number of better-than-stock grinds.. As the stakes go up and the usage of the vehicle becomes more intense the problem child that is the lifter set-up on the SR rears its ugly head. The OE lash adjusters cannot accommodate some high-lift cams because their aggressive ramp up and ramp down designs resulting in the lifter not being able to follow the profile of the cam. Tomei Powered's Lash Killer kit eliminates the hydraulic lifters in favor of a solid lifter, or solid pivot, that provides clearance for bigger cams while also introducing a fixed pivot height, which means no high rpm worries.
With a well-targeted turbo on point and a set of deep-breathing high lift cams as accomplices, the SR20DET is poised to generate some big numbers. The power potential that this flow of air represents must be mixed with the proper ratio of fuel in order for the magic to happen. A SARD 280lph fuel pump propels fuel through a high-flow fuel filter into a SARD Type-R adjustable fuel pressure regulator that can compensate via boost. At the combustion chamber, 740cc HKS injectors complete the journey and Blitz Iridium tipped plugs complete the combustion process. Spent gases are evacuated by a custom, one-off Kazama exhaust system.
Prodigious power puts an insane strain on the driveline. HKS comes to the rescue with its outlandish six-speed sequential transmission. This gearbox, perhaps more than any other single product, testifies to HKS' commitment to performance, and at $12,000 it ain't no cheap date. The sequential tranny is a must-have for time attackers and the Kazama Silvia runs an Ogura Racing Clutch twin-plate clutch set and Cusco limited-slip differential.
Time attackers are big fans of body tuning and the performance advantages and aesthetic impact of the parts. On the track, aerodynamic traits and weight reduction help the car get around the circuit. Kazama engineers produce multiple lines of body kits and aerodynamic parts, so the S15 runs Promode, a D1 spec kit that features front and rear bumper treatments with aggressive ducting, side steps and wide-body fenders. The front fenders add 40mm to the car while the rear tack on 30mm. A Top Secret GT wing finishes off the Nissan in high style.
Team Kazama is poised to put the hurt to other 2.0-liter hopefuls out there. As with all things time attack, it's just a matter of, well, time really.