Porsche takes the advanced heat-energy-recuperation technology originally developed for its Le Mans-winning 919 race car and applies it to its signature sportscar – the 911.
The gasoline-electric system, which goes under the name T-Hybrid, forms the central change to the facelifted seventh-generation 911 set for North American sales in September. It features an all-new turbocharged 3.6L boxer 6-cyl. in combination with a gearbox-mounted electric motor and lithium-ion battery.
Together, they provide the mildly restyled rear-wheel-drive 911 GTS, the first Porsche model to receive the new powertrain, with a combined 534 hp and up to 450 lb.-ft. (610 Nm) of torque, 60 hp and 30 lb.-ft. (41 Nm) more than the previous model, which used a twin-turbo 3.0L boxer 6-cyl. without hybrid properties.
Porsche claims a 0.4-second reduction in the 0-62 mph (100 km/h) time at 3.0 seconds in combination with a standard 8-speed dual-clutch gearbox. It also quotes 0-100 mph (161 km/h) and 0-124 mph (200 km/h) times that are a respective 0.9 second and 1.1 second quicker than before at 6.8 seconds and 10.5 seconds, along with a top speed incrementally increasing to 194 mph (312 km/h).
The improvements come despite a 100-lb. (45-kg) increase in curb weight for the updated 911 GTS at 3,516 lbs. (1,595 kg) – some 60 lbs. (27 kg) of which is contributed by the battery. But because it sits up front, the liquid-cooled unit is claimed to subtly improve the sportscar’s weight distribution at 37.3% to 62.7% front-to-rear.
The performance-enhancing potential of the hybrid drivetrain is also reflected in the latest 911 GTS’s official Nürburgring lap time, which is 8.7 seconds quicker than that of its predecessor at 7 minutes, 16.93 seconds, according to Porsche.
T-Hybrid stands for Turbo Hybrid. Key among its developments is the adoption of a new Borg Warner-produced turbocharger featuring a heat-energy-recuperation system that operates through the capture of exhaust gases.
Similar to that employed on the turbocharged 2.0L V-4 gasoline-electric hybrid powertrain used by the Porsche 919 race car, it is capable of generating up to 11kW of kinetic electricity in optimum operating conditions, including periods where the powertrain is under load.
Together with the energy-generation properties of the electric motor on a trailing throttle and energy recovery under braking, this has allowed Porsche to engineer the T-Hybrid system with a compact 1.9-kWh battery and not needing external charging.
“We produce the energy on board. It always recuperates – under acceleration, during braking and on a trailing throttle. Even at the top speed, we continue to store kinetic energy in the battery,” says Porsche 911 project leader Frank Moser.
With the electric motor operating on the driveshaft in combination with the internal-combustion engine, there is no provision for direct drive from the electric motor alone as with the E-Hybrid plug-in-hybrid powertrain used by the Cayenne and Panamera.
Porsche’s T-Hybrid system is based around a 3.6L version of its traditional horizontally opposed gasoline 6-cyl. The all-new unit, boasting a bore and stroke of 87.0 mm and 91.0 mm, receives a large single turbocharger driven simultaneously by the expended exhaust gas and an electric compressor.
The new turbocharger has been adopted in place of the twin exhaust-driven turbochargers of the existing 3.0L engine that other selected facelifted 911 models will continue using for the foreseeable future. Porsche says the introduction of an electric compressor increases the acceleration of the exhaust gas through the turbocharger, leading to a faster and more linear build-up of boost pressure over a wider range of revs for added response and acceleration.
Together with the turbocharger, the new Porsche engine also adopts a revised VarioCam camshaft control system with a 10.5:1 compression ratio.
All up, the internal-combustion engine develops 479 hp for a specific output of 133 hp per liter, along with 420 lb.-ft. of torque. It is supported by a disc-shaped electric motor integrated within the front section of a standard 8-speed dual-clutch gearbox. Manufactured by German component supplier ZF, the 360V synchronous unit develops up to 54 hp and 111 lb.-ft. (151 Nm) of torque at rotational speeds of up to 7500 rpm.
Together, the two power sources deliver a combined 534 hp at 6500 rpm and 450 lb.-ft. of torque on an impressively flat and extended range between 1950 and 6000 rpm.
The packaging of the 400V li-ion battery, produced by Hungarian firm Teconnex, and a pulse inverter used to power the electric motor within the front of the 911 has led to a 1.6-gallon (6 L) reduction in the size of the optional fuel tank at 22.2 gallons (84 L). The smaller 12V li-ion battery, meanwhile, has been relocated to a position underneath the rear seat.
Besides supporting rear-wheel drive, Porsche confirms the T-Hybrid system is also compatible with all-wheel drive, suggesting future incarnations of the 911 Turbo as well as other 911 models could benefit from the new powertrain technology.
Porsche has significantly improved the aerodynamic efficiency of the 911 by incorporating new active front air ducts with five vertical louvers on each side. They open and close depending on the cooling demands of the front-mounted radiators and brakes.
The central lower space within the facelifted 911’s newly designed front bumper is now occupied by radar and ultrasonic sensors, with the indicator functions incorporated within the standard LED Matrix headlamps instead of within the separate LED units of its predecessor.
At the rear are newly designed OLED tail lamps, a revised rear spoiler and reworked diffuser.
With an optional Aerokit, the new 911 GTS is claimed to provide a big reduction in lift, developing 22 lbs. (10 kg) of downforce at its 194-mph top speed compared with the 66 lbs. (30 kg) of lift generated by the standard model.
In combination with new optimized wheels, the drag coefficient has been reduced from a previous 0.32 to 0.27 – lowest ever for the 911.
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