The Porsche 911, an automotive icon, continues its evolutionary journey, captivating enthusiasts with each generation. Staying true to its legacy of meticulous development, Porsche introduces a groundbreaking technological advancement in the latest 911: the performance hybrid drive system. Debuting in the new 911 Carrera GTS, this T-Hybrid system marks a significant milestone, seamlessly integrating into the 911’s architecture while upholding its renowned performance standards.
This innovative concept draws heavily from Porsche’s extensive motorsport experience. Engineers have meticulously crafted a lightweight drive unit specifically tailored for the 911. This system comprises an electric exhaust turbocharger (eTurbo), a compact, high-voltage battery, efficient power electronics, a newly engineered 3.6-liter boxer engine, and a reinforced eight-speed dual-clutch transmission (PDK) with an integrated electric motor. This combination of components empowers the T-Hybrid system to achieve an exceptional equilibrium between exhilarating performance, enhanced efficiency, and minimized weight.
The Electric Turbocharger: Revolutionizing Response in the Porsche 911 Hybrid
At the heart of the new 911 T-Hybrid system lies the specially developed eTurbo, an electric turbocharger without a wastegate. This innovative design incorporates an electric motor positioned directly on the turbocharger shaft, nestled between the compressor and turbine wheels. This motor can instantaneously spin up the turbine, independent of engine speed or load. This rapid response is crucial for both performance and emission control.
To maintain optimal engine performance and a clean combustion process (lambda = 1 air-fuel mixture ratio), wider exhaust tracts are typically required. However, these larger exhaust pathways can lead to undesirable ‘turbo lag’. The eTurbo’s electric motor effectively eliminates this lag by drastically reducing the turbo spool-up time. This ensures that full boost pressure is available almost immediately, allowing the 3.6-liter boxer engine to consistently maintain the ideal air-fuel mixture and generate torque swiftly.
The result is instant engine response in all driving scenarios and linear power delivery. The system delivers an impressive 500 Nm of torque at just 1,500 rpm, with the full 610 Nm readily accessible from below 2,000 rpm.
The eTurbo is ingeniously designed to function bidirectionally. While it can apply torque to the turbocharger shaft, it also acts as a generator, converting turbine rotation into up to 11 kW of electrical power. This generated energy is utilized to power the electric motor within the Porsche dual-clutch transmission (PDK) or to replenish the high-voltage battery. The eTurbo’s efficiency and responsiveness eliminate the necessity for a second turbocharger. Boost pressure regulation is automated through the electric motor’s generator function, negating the need for a traditional wastegate. Positioned behind the boxer engine on the right side, the eTurbo receives exhaust gases from both cylinder banks via newly designed exhaust manifolds. The corresponding charge-air cooler, positioned above the boxer engine and cooled by air intakes in the rear lid, has been made even more efficient than its predecessor.
Enhanced PDK and Integrated Electric Motor in the 911 Carrera GTS Hybrid
Porsche engineered a bespoke PDK transmission specifically for the T-Hybrid 911. While based on the gearbox of previous models, it incorporates significant enhancements. The clutches, gear sets, and bevel-gear drive have been strengthened to accommodate the substantial increase in system torque. Furthermore, a taller final-drive ratio contributes to reduced engine speeds, especially at higher velocities.
A permanently excited synchronous electric motor is seamlessly integrated within the gearbox housing. It integrates with the existing gearbox oil cooling system and connects directly to the crankshaft via the dual-mass flywheel. This compact integration optimizes weight and provides immediate power assistance to the powertrain. Despite its small size – just 286 mm in diameter and 55 mm in length – this module delivers 150 Nm of drive torque from standstill and up to 40 kW (54 PS) of power. In generator mode, it can feed up to 40 kW back to the high-voltage battery. This energy regeneration occurs during braking, deceleration when coasting, or through engine load point shifting, where excess engine power is used to drive the generator. The electric motor also functions as both the starter and alternator, further contributing to weight reduction.
Compact High-Voltage Battery: Powering the Porsche 911 Hybrid System
The T-Hybrid system is powered by a compact and lightweight high-voltage battery. Operating at 400 volts with a gross capacity of 1.9 kWh, it maintains a remarkably small footprint. Weighing approximately 27 kg, its dimensions are comparable to a conventional 12-volt AGM starter battery. Positioned in the front, under the bonnet of the new 911 Carrera GTS, this placement aids in optimal weight distribution. The battery, comprised of 216 round cells, features water cooling and sophisticated thermal management to ensure consistent high performance by actively regulating temperatures at both cell and module levels.
Complementing the high-voltage system is a specially developed 12-volt starter battery for the T-Hybrid drivetrain. This lightweight lithium iron phosphate battery (LiFePO4), with an energy capacity of 40 Ah and a height of just 90 mm, weighs a mere seven kilograms – significantly lighter than a standard 70 Ah lead-acid battery which weighs around three times as much. This lithium iron phosphate battery offers superior high-voltage stability, enhanced charge acceptance, high cycle stability, and extended service life.
The New 3.6-Liter Boxer Engine: Core of the Porsche 911 Carrera GTS Hybrid
The heart of the 911 Carrera GTS remains its exhilarating combustion engine. Porsche has developed a new six-cylinder boxer engine, engineered for future-proof performance. Engineers increased the displacement from 3.0 to 3.6 liters by enlarging the bore to 97 mm and stroke to 81 mm, while incorporating the proven VarioCam technology. This precise camshaft control, tailored to speed and load conditions, optimizes fuel consumption while delivering high power and torque. With the electric motor handling alternator functions and the air conditioning compressor being electrically powered, the traditional belt drive is eliminated, freeing up space above the engine for the pulse inverter and DC-DC converter.
The six-cylinder boxer engine in the new 911 Carrera GTS adopts solid roller cam followers, a technology derived from motorsport. Compared to the bucket tappets in the previous model, these reduce frictional losses, improving efficiency and enhancing valve train robustness at high speeds. Furthermore, manual valve clearance adjustments during maintenance are no longer necessary.
Enhanced Dynamics and Reduced Emissions: The Benefits of Porsche 911 Hybrid Technology
Even without electrical assistance, the boxer engine delivers an impressive 357 kW (485 PS) and 570 Nm of torque. Combined with the high-voltage system, eTurbo, and electric motor in the PDK, the T-Hybrid system achieves a total system output of 398 kW (541 PS) and 610 Nm. This represents a power increase of 45 kW (61 PS) compared to its predecessor. The added electric power and the significantly reduced response time of the eTurbo dramatically improve performance, particularly from a standstill. In full acceleration from a standstill and from idle speed, the new 911 Carrera GTS covers a greater distance in the first 2.5 seconds compared to its predecessor – a lead exceeding the length of a car.
The new 911 Carrera GTS Coupé, equipped with Launch Control Start, accelerates from 0 to 100 km/h in a mere 3.0 seconds and reaches a top speed of 312 km/h.
Each component within the drive unit contributes to multiple functions. The performance hybrid system achieves enhanced driving dynamics with optimized CO2 emissions and minimal additional weight. The overall weight increase compared to its predecessor is just 50 kg. The drive system maintains an ideal air-fuel ratio (lambda value of 1) in all operating modes, even at full load, ensuring efficient and clean combustion.
The innovative T-Hybrid system in the new 911 Carrera GTS seamlessly integrates with Porsche’s electrification strategy, demonstrating continuous progress in developing high-performance solutions. Frank Moser, Vice President Model Line 911 and 718, summarizes, “Water cooling, turbocharging, performance hybridisation: with the T-Hybrid system, we are taking the next logical step in the continuous, innovation-driven development of our core models. It significantly increases efficiency and future-proofs the 911 philosophy with even better performance.”
