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Case Study: The mid-engined 911
At the 2017 Los Angeles Auto Show, Porsche Motorsport unveiled its most radical 911 RSR to date, with the most interesting design detail being the switch to a rear-mid engine position
Porsche is set to tackle the 2017 racing season with an all-new GT racer. The newly developed 911 RSR is said to 'make full use of the breadth of the Le Mans 24 Hours GT regulations', and in addition to a focus on lightweight design, the RSR features an all-new 'ultra-modern', flat-six engine positioned for the first time in front of the rear axle. The extremely lightweight four-liter powerplant features such technologies as direct fuel injection and rigid valve drive to deliver 'outstanding' fuel efficiency.
"While retaining the typical 911 design, this is the biggest evolution in the history of our top GT model," said head of Porsche Motorsport Dr. Frank-Steffen Walliser. "For the 911 RSR, we deliberately focused on a particularly modern and light normally-aspirated engine, as this gave our engineers immense latitude in developing the vehicle. Apart from that, in principle, the LM-GTE and GT Le Mans class regulations stipulate the absolute equality of various drive concepts, as the torque characteristics of turbo and normally aspirated engines are aligned."
The new 911 RSR is claimed to be a 'completely new' development of race car. What this translates to in the RSR is an all-new suspension arrangement, body structure, aerodynamic approach, aforementioned engine and transmission. By moving the engine forward within the RSR's packaging, Porsche has been able to install a larger rear diffuser. Combined with a top-mounted rear wing, which is adopted from the LMP1 919 Hybrid, the German company is claiming 'significant improvements' in regard to the level of downforce generated, as well as improved aerodynamic efficiency.
The flat-four, naturally-aspirated engine, depending on the size of the restrictor, develops approximately 510hp. This is transferred to the 12.2" wide rear wheels via a sequential six-speed gearbox with a magnesium housing.
On board, the 911 RSR continues to add technologies. Its introduction marks the first time a Porsche GT racecar features state-of-the-art assistance systems. The new 911 RSR is equipped with a radar-supported collision warning system, the popularly-called "Collision Avoidance System". Even in the dark, the faster prototypes are detected early enough that misunderstandings can be avoided.
Elsewhere, a new safety cage design and a new, rigidly mounted racing seat enhance driver safety. With the seat fixed to the chassis, the pedals can now be moved and adjusted to fit the driver.
The new 911 RSR's serviceability has also been significantly improved. Entire elements of the carbon-fiber body can be completely exchanged in a very short time thanks to quick-release fasteners. This also means that changes to the suspension can be performed by teams much more quickly and easily.
With the look of the body wrapping, the 911 RSR is striking out in a new direction. For the first time, the GT racer bears the new factory design that has further developed the clear and dynamic design language of Porsche Motorsport. From a bird's eye view, a hint of the Porsche emblem silhouette can be seen. The basic colors remain white, red and black.
In the 2017 season, the factory is expected to run the new 911 RSR at 19 outings equating to more than 140 hours of racing. With two factory-entries, Porsche will tackle the FIA World Endurance Championship (WEC) including the 24 Hours of Le Mans as well as the North American IMSA WeatherTech SportsCar Championship. The new racer will celebrate its debut under the toughest conditions at the IMSA season opener in Daytona on January 28-29.
"We're very well prepared for this," added Marco Ujhasi, head of GT Works Sport. "Since its first rollout in Weissach in March this year, we've covered more than 21,000 test miles (35,000km) on racetracks in Europe and North America - that's more than in the development of any other previous Porsche GT racer."
Technical Data - 2017 Porsche 911 RSR
Weight: 1,243kg (base weight per regulations)
Length: 4,557mm (without splitter, rear wing, diffuser)
Width: 2,042 mm at the front axle / 2,048 mm at the rear axle
Wheelbase: 2,516 mm
Water-cooled six cylinder boxer, positioned in front of the rear axle; 4.0-liter, stroke 81.5mm, bore 102mm; Approximately 510 hp (375 kW) depending on restrictor; four-valve technology; direct fuel injection; dry sump lubrication; single mass flywheel; power output limitation via restrictor; electronic throttle.
Six-speed sequential constant-mesh gearbox; two-shaft longitudinal layout with bevel gear; shifting via electronic shift actuator; shift paddles on the steering wheel; magnesium gearbox casing; multi-disc self-locking differential with visco unit; three disc carbon race clutch.
Weight-optimized chassis in combined aluminum steel design; removable roof hatch for cockpit access; lifting bushes integrated in the roof; FT3 fuel cell in front of the car; welded-in roll cage; seat pursuant to FIA 8862-2009; rigidly mounted to the chassis; six-point safety harness for use with HANS; longitudinally adjustable pedals; bodywork made of CFRP, quick-change; rear wing with "swan neck" mounts; four-post air jack system with safety pressure valve; electronically activated fire extinguisher system; heated windscreen.
Front axle: Double wishbone front axle; four-way vibration damper; twin coil spring setup (main and helper spring); anti-roll bars, adjustable by blade positions; electro-hydraulic power steering
Rear axle: Integrated rear axle subframe with double wishbone axle; four-way vibration damper; twin coil spring setup (main and helper spring); anti-roll bars, adjustable by blade positions; electro-hydraulic power steering; tripod drive shafts.
Two independent brake circuits for front and rear axle, adjustable via balance bar.
Front axle: One piece aluminum six-piston racing calipers with quick coupling; internally ventilated steel brake discs, 390mm diameter; race brake pads; optimized brake cooling ducts.
Rear axle: One piece aluminum four-piston racing calipers with quick coupling; internally ventilated steel brake discs, 355mm diameter; race brake pads; optimized brake cooling ducts.
Front axle: One piece forged light alloy wheels, 12.5Jx18 offset 25 with center-lock nut; Michelin slick 30/68-18.
Rear axle: One piece forged light alloy wheels, 13Jx18 offset 37 with center-lock nut; Michelin slick 31/71-18.
Cosworth Central Logger Unit; CFRP multi-functional steering wheel with integrated display; shift paddles and quick release; Collision Avoidance System; controlled alternator in connection with LiFePo4 battery; LED headlights; LED taillights plus rain light; illuminated car number and leader light system; black light inside cockpit; electric adjustable wing mirrors with memory function; tire pressure monitoring system (TPMS); drink system; air conditioning system; membrane switch panel on center console with fluorescent labeling.