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Nissan GT-R: Too Much is Never Enough

Any doubts that technology could be harnessed to produce supercar-surpassing performance in a well-rounded package have been put to rest. "Mr.

Any doubts that technology could be harnessed to produce supercar-surpassing performance in a well-rounded package have been put to rest. "Mr. Ghosn didn't just open the cash register and let the engineers go wild," says Peter Bedrosian, regional product manager, Product Planning Nissan Sports Cars, Nissan North America, speaking of the Nissan-Renault chairman, "but he gave full support to moving the R35 GT-R from sports car to supercar." The concept behind the car-"Anyone, Anytime, Anywhere"-became a focal point for expanding the GT-R's performance definition far beyond that of a track queen capable of fast lap times and impressive performance numbers. "This is an all-weather supercar," says Bedrosian, "that was tested in Michigan's Upper Peninsula during the worst possible weather, and can be used in conditions normally seen only by daily-drivers while other supercars sit in the garage."

 

Redefining 'Hybrid'

Though similar in many respects to the FM platform, the GT-R is built on a unique ultra-high-strength steel "Premium Midship" (PM) hybrid platform that also utilizes both aluminum-die cast and sheet-and carbon fiber. "The front inner-fender wells and shock towers encompass a one-piece cast aluminum shell," says Bedrosian, "and we've seen input forces as high as 5,000 kg on the towers." Each door is built around a vacuum die-cast aluminum frame and covered by a sheet aluminum skin. The same process is used to form the rear bulkhead/seatback support structure, driveshaft tunnel stays, and the asterisk-like web of the roof inner panel. A blow-molded polypropylene belly pan extends from the splitter below the lower air intake to just past the engine compartment, and is mated to a rear pan made of carbon SMC. A lightweight injected carbon fiber element carries the headlights and heat exchangers.

The main structure is built on jigs that control deformation and allow the build team to keep tolerances under 1.0 mm when measured diagonally across the body. The body panels are triple stamped, says Bedrosian, "to give greater definition of the character lines and impart greater strength," and the limited-availability Super Silver paint job is hand-polished using both medium- and fine-grit abrasives and finished with three clear coats. In addition, each body is placed on a shaker table where technicians, says Bedrosian, "are using the results to improve the weld nugget size and spacing based on its effect on the torsional and bending response of the structure." 

 

Powerful and Clean

Though Nissan has made a cottage industry of expanding and modifying its VQV6 engine, the GT-R gets a new V6. It is based on a closed-deck aluminum block with plasma-sprayed cylinder bores. The plasma surfaces are lighter than cylinder liners and increase cooling capacity by reducing the distance from the piston to the water jacket. "The combustion temps run about 1,000°C," says Bedrosian, "and the proximity of the cylinder to the coolant means we can run the engine leaner." That helps it get a ULEV emission rating, an unexpected accomplishment for an engine with 480 hp @ 6,400 rpm and 430 lb-ft of torque from 3,200-5,200 rpm. Each twin-turbo VR38DETT is built by a single technician in a climate-controlled clean room.

The clean room-built GR6 rear transaxle's center of gravity is below the axle centerline, and mounts within the rear steel subframe. BorgWarner helped design and develop the Aichi Kikai-supplied six-plate dual-clutch gearbox which boasts 12 friction faces, triple-cone synchronizers on every gear, a dry sump lubrication system, and a GKN-supplied limited-slip differential that also works under braking. According to Bedrosian: "BorgWarner spent a lot of time working on reducing the hydraulic pathways and optimizing the shift logic to reduce shift time to 0.2 sec from the time the steering wheel-mounted paddle is pulled to the time power is delivered to the wheels."

The engine and transmission are joined by a carbon fiber driveshaft instead of a torque tube so the wheels can react independently without one axle having an effect on the other. The Attesa-E-TS all-wheel-drive system has a rear torque bias with 100% sent to the rear wheels under normal driving and as much as 50% flowing to the front wheels when needed. Speed, lateral acceleration, transverse acceleration, steering angle, tire slip, road surface, and yaw rate are either measured directly or inferred from available data to continuously vary the torque split, and a GT-R-specific yaw-rate feedback control looks at the difference between driver input and the actual yaw rate to fine-tune the split.

 

Stopping, Steering, and Damping

Both the double-wishbone front and multi-link rear suspensions are attached to tubular steel subframes at six mounting points. Nonlinear springs made to race car tolerances and continuously adjustable Bilstein DampTronic shocks with multiple driver-selectable damping modes are used at each corner. In addition, the aluminum steering rack has a four-point mounting and high-stiffness insulator, while the factory-set rear camber and toe settings are claimed to never change no matter the speed or braking level. (The GT-R's claimed maximum rates are 2.0 g cornering, 1.0 g accelerating, and 1.7 g decelerating.) Unlike previous GT-Rs, four-wheel steering is not used.

Brembo supplies the monobloc radial-mount calipers and full-floating, cross-drilled, two-piece rotors. According to Jim Hodgman, manager, High Performance Div., Brembo North America: "Nissan requested the front calipers have three mounting bolts and a 7.5-mm backing plate and the rears have two bolts and a 6.5-mm plate to eliminate any flexing." Stainless steel piston inserts in the front calipers radiate heat away from the brakes, and a small-to-large piston orientation keeps the pads in line under heavy braking. On the other hand, the 20-in. Rays wheels were modified to add serrations on the inner bead to keep the wheel from spinning inside the tire, and the spokes were strengthened to prevent them from twisting under hard cornering as they had while testing at Germany's Nurburgring. Fitted with the standard Japanese market tires, the $70,000 Nissan GT-R recently lapped that track in 7:29, a full three seconds faster than Porsche's $440,000 Carrera GT. A lighter V-spec version of the GT-R is in the works.