Domination comes in many forms. For the last two seasons in the JGTC's GT500 Class, it has come in the form of a Nissan. Specifically, the Skyline GT-R and 350Z.
In 2003, Nissan won the JGTC GT500 Class with its Skyline GT-R and by the time you read this the NISMO Team will have completed the 2004 season with the same result and the same engine, this time wrapped in carbon-fiber 350Z bodywork.
When the JGTC visited the United States last December, SCC had the chance to spend a few hours with the winning car from the 2003 season. It uses a destroked version of the VQ30DE powerplant. However, short of the basic engine architecture and passenger compartment stampings, there's very little Skyline remaining.
The rest of the car is purpose-built with one thing in mind-winning races. The floor of the unibody is cut out and replaced with a smooth flat-bottom carbon-fiber floor pan. A chrome-moly tube frame snakes through the remaining unibody, creating its own structure. The entire body except the roof skin and the inner quarter panels of the rear fenders are made of carbon fiber.
In short, this is one the most advanced racecars on the planet.
The engine is set back in the chassis behind the centerline of the front axle, giving the car a front-midengine layout for superior weight distribution. NISMO increased the bore to 93mm while destroking the crank to 73.3mm to reduce piston speed. This bore and stroke yields a displacement of 2987cc. Dry-sump lube ensures constant lubrication.
The turbocharged engine has an unusually high compression ratio of around 11:1. The heads are ported but valve and camshaft dimensions are kept secret. The VQ's intake manifold is replaced with a large-plenum, short-runner setup more appropriate for forced induction. There are two 330cc/min injectors per cylinder running in a staged configuration.
Since JGTC cars are limited to about 500 hp, the twin turbos breathe via two rule-mandated 30.2mm restrictors. Exhaust gases exit through inconel headers that bolt to a pair of IHI ball-bearing turbos.
Interestingly, the turbos do not use external wastegates more typical on race applications. Instead, the internal wastegates utilize custom-machined, billet actuators. The ECU controls pressure to both sides of the wastegate actuator diaphragm to maximize boost response.
The Hitachi ECU has multimap capability for both fuel and spark. It also controls torque reduction via a fuel cut during upshifts to speed shifting of the constant-mesh, sequential gearbox. An advanced, map-selectable anti-lag system keeps the turbos spooled when the throttle is closed. The engine puts out approximately 495 hp at 5600 rpm and 540 lb-ft of torque at 4000 rpm.
Airflow management both over and through the car are critical elements in its design. The Skyline's leading edge is capped with a carbon/Kevlar splitter that channels air over the car and gives a larger aerodynamic surface to increase front downforce.
Aft of the splitter there are two venturies molded into the carbon bellypan that empty into the low-pressure wheelwell area. The wheel wells are vented through the front fenders with internal dividers to help keep the flow even down the sides of the car. In a fit of dual-purpose design, the engine's exhaust gases exit through the same vents to help evacuate air.
Both sides of the front bumper feature a pair of aerodynamic strakes. Their function, in addition to creating downforce, is to help the carbon side skirts create a vortex down the side of the car, which keeps air from spilling under the bellypan.
Vents in the nose feed two large air-to-air intercoolers, the front brake rotors and heat exchangers for the oil and power steering fluid. However, air won't go in if it doesn't have a way out, so large vents in the hood provide that exit.
The rear decklid has scoops that feed a heat exchanger for the rear-mounted radiator. Additional vents feed air to the rear brakes and the transaxle heat exchanger. A massive carbon buttress supports the rear wing, rear carbon quarter panels and rear bumper. Virtually every piece of ducting, bodywork and wing structure behind the rear axle is made of carbon fiber.
The front suspension uses unequal-length A-arms with push rods and rocker arms operating three-way adjustable, remote-reservoir coil-over dampers. Every bit of suspension design is as elegant as it is expensive. The rocker arms give the suspension a rising rate and allow packaging of the steering rack and tie-rods to eliminate bump steer. This necessitates an elaborate bell-crank and pushrod linkage to transfer motion from the forward-mounted steering rack to the rear-mounted tie rods. The rear suspension is also comprised of unequal-length A-arms with pushrod-activated dampers.
Huge brakes are required to slow the 2,535-pound car. The front rotors are 15.4 inches in diameter and are stopped by six-piston, liquid-cooled AP calipers. The rear brakes are 13.9 inches in diameter with similar calipers. Topping off the brakes, the GT-R sports fat 13x18-inch Volk TE37 wheels carrying 330/40-18 racing rubber.
Surprisingly, NISMO's engineers figured the GT-R was better off without its renowned but heavy all-wheel-drive system. This car and the current 350Z are rear-wheel drive. To improve weight distribution, the Skyline has its Hewland six-speed sequentially shifted transaxle mounted in the rear of the car.
The Hewland transfers power to the rear axles via a locked differential at most tracks. The locked differential can be substituted for a conventional clutch-type limited slip depending on track configuration. The rear-mounted transaxle gives the car a rearward weight bias-unusual for a front-engine, rear-drive car. Power is transferred to the transaxle via an ultralow-inertia 5.5-inch, triple-plate carbon clutch.
The interior of the car reflects the NISMO team's excruciating attention to detail. There's a Pi dash in the steering wheel that controls data logging functions. The driver can control the front and rear anti-roll bar stiffness, brake proportioning, brake pedal height, engine calibration and anti-lag mapping from switches mounted on the all-carbon center control panel.
All this exquisite, expensive and outrageous hardware and design work translate into one of the most thoroughly developed, beautifully prepared and overwhelmingly dominant racecars in the world.