Nissan's return to professional road racing is rallied around this car. And expectations are high.
Built to compete in SCCA's Speed World Challenge Cup, which has grown into North America's premier Touring Car series, this Sentra will be campaigned by the powerhouse team of RealTime Racing and driven by the most successful driver in World Challenge history-four-time World Challenge champion and RealTime owner Peter Cunningham.
In other words, Nissan has spent a gazillion dollars for the best and Cunningham, who's best known for his victories behind the wheel of the orange and white RealTime Racing Integra Type R, is expected to deliver wins, plain and simple.
The rules for World Challenge are quite flexible and designed for fair competition and close spectator-pleasing racing. The SCCA determines what modifications are allowed to the production-based vehicles and assigns a minimum weight and tire size to control the cars' competitiveness. If a car becomes too dominating, weight is added to it. If another car struggles because of a weak engine, more engine mods are allowed for that make and model. This format ensures exciting action and encourages manufacturer involvement.
The tight competition, the factory involvement and the flexible rules lead to cars built to a high degree of technical sophistication, much greater than your typical production-based racer, and the RTR SE-R is a prime example of this exotica.
Let's start with the engine. Nissan's controversial QR25DE, unlike the SR20DE it replaced, wasn't designed as a free-revving performance engine. Instead, the four cylinder was designed to have maximum power density and low-end torque. Saddled with a 100mm bore and awful stroke-to-rod length ratio, the QR's tremendous piston speed is quite a handicap when trying to turn it into a racing engine.
To get the engine output up to competitive power and torque levels, Ed Pink was contracted to do the engine development and assembly, while Nissan Motorsports and Nismo provided the essential parts.
The 2500cc engine features a 89mm stock bore and super long 100mm stock stroke. To help combat the piston speed issues and to improve high-rpm breathing, Ed Pink increased the rod length by an undisclosed amount and replaced the QR's wimpy stock pieces with special billet parts to handle the extra strain. The 13:1 compression forged pistons are hung on the custom rods to put maximum squeeze on the mixture.
The crank and block remain stock, but an Ed Pink-developed dry sump system greatly reduces windage-induced power losses and ensures the engine's bearings and valvetrain a continuous supply of high-pressure, unaerated oil under all conditions. The dry sump system also has a very trick internal air/oil separator so the tank and peripherals can be much smaller and more compact than typical dry sump systems.
Nissan Motorsports camshafts and valve springs help the engine breathe to its 6900-rpm rev limit, up from the stock 6100 rpm. This may sound pitifully slow for a racing engine, but remember the long stroke and note that at 6900 rpm, the QR's piston speed is higher than that of an F1 car.
Although the QR25DE cylinder head flows well from the factory, Ed Pink did some porting and polishing for additional flow. Feeding the head is a trick RTR carbon-fiber air intake/air box/filter system with duct work that rams in cold air from a high-pressure zone in the front of the car. Burnt gases are exhausted through a hand-fabricated RTR header leading through a ducted exhaust, which runs inside the car to increase ground clearance and reduce drag.
An EFI Technologies stand-alone engine management system controls the intake cam phasing, fuel and spark. It also provides output for the multi-function carbon-fiber-enclosed digital dash and multi-channel data logging system, which logs an astounding 18 engine and 18 chassis inputs simultaneously. EFI
Technologies also fabricated the EMI shielded aircraft-style connected wiring harness. EFI Technologies boxes are popular with big-budget professional race teams due to their computing power, tremendous capability for control and mil spec toughness.
The ECU fires bigger Bosch injectors andNissan's DIS (direct fire ignition system), which has been pumped up with greater primary voltage from a capacitive discharge system. A KFI fuel pressure regulator and filter ensures a steady and clean supply of fuel to the thirsty, naturally aspirated motor. All told, the engine's output is an astounding 253 hp at 6900 rpm with 209 lb-ft of torque at 5000 rpm delivered over a wide, tractable band.
The power is delivered through an exotic Tilton low inertia 5.5-inch dual-disc clutch with a feathery flywheel using the stock 2004-spec., closer-ratio transmission with Nissan's already excellent stock helical limited slip.
After stripping the car to a shell and sandblasting off all of the paint and sound insulation, RTR constructed an elaborate multi-point roll cage to both stiffen the chassis and provide impact protection. The rules-mandated 2,400 pounds gave the RTR crew a lot of leeway in building the stout cage, which is made of TIG-welded thinwall seamless chrome-moly tubing. With triangulating bracing and punched gussets everywhere, the cage is a work of art.
For better weight distribution, the cage, steering wheel and pedals are positioned rearward to move the driver back. Sparco supplied the seat, the quick release steering wheel and the five-point harness system.
The fully adjustable suspension is built around exotic three-way adjustable Moton shocks. The remote reservoir Motons are externally adjustable for compression, low-speed and high-speed rebound damping, allowing fine control of body motion from bumps to roll, dive and squat. Incredibly stiff 1000 in/lb Eibach ERS springs hold up the car.
Fabricated front lower control arms have the pivot points relocated to reduce bump steer to the maximum amount allowed under SCCA rules. The rear Nissan twist beam axle has been ditched for a lighter and stiffer tubular three-link assembly, with an adjustable Panhard rod replacing the bind-inducing stock Scott-Russell linkage. The Panhard rod is adjustable so the rear roll center can be manipulated. Tubular torsion beam and blade-type, driver-adjustable swaybars give on-the-fly balance options to the driver. To speed up pit stops, a built in air jack system, just like the type found on Indy cars, is used.
For brakes, RealTime chose four-piston monoblock Brembo calipers, which grip two-piece 12.6-inch front rotors with Hawk Blue brake pads. Two-piston Brembo rear calipers also stuffed with Hawk pads clamp on two-piece 10.9-inch rear rotors. The calipers are fed by Goodrige braided steel lines and pressurized by a dual Brembo master cylinder system with a brake bar and a driver-adjustable proportioning valve to give precise control to the front-to-rear brake bias.
It all rolls on lightweight Nismo 17x7.5 forged five-spoke wheels with a 40mm offset and rules-mandated Toyo T1-S tires in 225/45-17.
RTR is also responsible for the trick bodywork, which consists of a carbon-kevlar epoxy front fascia, splitter, hood, trunk, rocker panels, rear wing and undertray. The aero pieces are truly functional and really help keep the car sucked down to the road.
In its first outing at Mosport this past May, the RTR SE-R did well, qualifying fifth out of a field of about 40, but broke an axle at the start. The car has since been repaired and after a little development, should be highly competitive.
Maybe you'll be hearing of its first wins by the time you read this. This car certainly has the heritage, the team and the driver to be a winner.
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