DFI injects fuel directly into the combustion chamber via a solenoid-operated injection valve within a few milliseconds at a pressure of up to 120 bar.
Efficient combustion is achieved by ensuring even distribution of the air-fuel mixture, with injection and cone angles optimized for torque, power output, fuel consumption and emissions.
With direct injection, the EMS SDI 3.1 engine control device can individually adjust the injection timing of each cylinder and the injection rate of each cylinder bank, thereby optimizing the combustion process and improving fuel economy. . Hot film air quality sensors control airflow so that the proper mixture is always maintained in the combustion chamber.
When the engine speed reaches 3,200 rpm, the engine operates in dual-injection mode; when the engine speed reaches 2,500 rpm, the engine can even operate in triple-injection mode. The required fuel volume is divided between two or three consecutive injections, allowing faster heating of the catalytic converter after a cold start and greater torque in the high load range.
DFI improves the internal cooling of the combustion chamber by achieving mixing directly in the cylinder, which will lead to a higher compression ratio (12.5:1), helping to provide more output power and improve Engine efficiency. Depending on the model, CO2 emissions can be reduced by up to 15%.
Fuel injection is controlled by an electronic engine management system. The exhaust cleaning system helps protect the environment by ensuring exhaust emissions are well below the strict EU5 emission standards. VarioCam Plus combines variable valve timing with two-stage lift on the intake side, resulting in smoother operating characteristics, better fuel economy and lower exhaust emissions, as well as higher high-rev output power and low-rpm torque.
This two-in-one engine concept adapts to the driver's commands. The result is faster acceleration and very smooth running characteristics.
Changes in intake timing are continuously controlled by electro-hydraulic rotary vane adjusters located on the top of the corresponding camshafts.
In order to improve the throttle response during the warm-up phase, the VarioCam upgraded version selects high valve lift and delays the valve timing. In the medium and low load range, the system selects low valve lift and advances valve timing, which can reduce fuel consumption and exhaust emissions. High valve lift produces higher torque and maximum power output. The optional Porsche Doppelkupplung (PDK) Porsche dual-clutch transmission has both manual and automatic shifting modes, enabling smooth shifting operations without interrupting power transmission. This not only significantly improves acceleration performance and reduces fuel consumption, but the comfort of the automatic transmission is not affected at all.
PDK*** has 7 gears, of which 1st to 6th gear adopt a sports transmission ratio, reaching the highest speed in 6th gear. 7th gear has a wider gear ratio and therefore uses less fuel.
PDK is like combining two gearboxes, so it requires two clutches. It is essentially a dual wet clutch gearbox.
This dual clutch provides an interactive, non-rigid connection between the engine and gearbox via two separate input shafts (Input Shaft 1 is nested within the hollow Input Shaft 2).
Power flow from the engine is transmitted through only one clutch at a time, while the other clutch preselects the next gear. The traditional shifting method is no longer used when shifting gears. Instead, one clutch disengages while the other engages. As a result, the gear shifting process is completed within a few milliseconds. Clutch 1 controls odd-numbered gears (1st, 3rd, 5th, 7th) and reverse gear. Clutch 2 controls even-numbered gears (2nd, 4th, 6th). The crankshaft transmits the engine torque to the dual flywheel, which then transmits it via the clutch housing to the multi-plate clutch, or more precisely to the outer clutch disk carrier.
Under the action of oil pressure, clutch 1 is engaged and forms a friction connection with the input shaft 1. At this time, the torque will be transmitted to the rear axle through the differential, or to the front and rear axles on all-wheel drive 911 models.
During this period, PDK has pre-selected the next gear. The engine torque is already acting on the other outer clutch plate carrier and responds to the shift signal by initiating an overlap shift, i.e. clutch 1 is disengaged and clutch 2 is engaged.
A non-rigid connection to input shaft 2 is thus established and the power is transmitted to the wheels. The engaged gear will be displayed on the instrument cluster.
PDK has unique advantages. Faster gear changes and uninterrupted power transmission allow the vehicle to accelerate faster, providing a more dynamic driving experience and improving agility. Depending on how the gearshift program is set, gear changes can be optimized for comfort or sporty handling.
The gearbox is more compact, resulting in reduced rotating mass, which means more direct engine response and a lighter system.
Compared with the manual transmission, equipped with a 7-speed with a larger transmission ratio, the dual-clutch transmission helps reduce fuel consumption and emissions. When paired with the new engine, fuel consumption can be reduced by up to 13% and carbon dioxide emissions by up to 15%, depending on the model.
In combination with the optional Sport Chrono upgraded package, PDK can also be enhanced with the functions of "Launch Control" and "Racing Shift Strategy". This new three-spoke sports steering wheel designed specifically for PDK has two ergonomically designed rocker switches. Press one of the switches with your thumb and the PDK will upshift. Pull one of the switches with your index finger and the PDK will downshift. You can use either the left or right button to complete the operation.
On customer request, the sports steering wheel for PDK is also available as a multifunction steering wheel (available in glossy leather, aluminum look, carbon fiber or Macassar ebony trim). A steering wheel heating system is available as an option with PDK. The gear selector for PDK is ergonomically designed and offers excellent functionality, allowing you to shift gears manually.
The control concept is the same as the rocker switch on the PDK sports steering wheel, that is, pressing the rocker switch forward can upshift, and pulling the rocker switch backward can downshift. Even if the gear selector is set to automatic mode, you can shift manually using the rocker switches on the steering wheel. In the 911, engine power is not the only priority; how it is effectively and consistently transmitted to the road is also very important. Four-wheel drive systems are one solution to this problem. An even better solution is the intelligent Porsche Traction Management (PTM), which includes permanent all-wheel drive with an electronically controlled multi-plate clutch, Automatic Brake Differential (ABD) and anti-skid acceleration. System(ASR).
This all-wheel drive system, which was previously only available on the 911 Turbo, is now standard on the all-wheel drive 911 Carrera 4 and 911 Targa 4 models. Equipped with this system, the power distribution between the front and rear axles is no longer completed by a viscous multi-plate clutch, but is actively regulated by an electronically controlled multi-plate clutch.
Compared with viscous multi-plate clutches, electronically controlled multi-plate clutches respond more quickly because the former only adjusts the clutch when there is a difference in speed between the front axle and the rear axle. By continuously monitoring driving conditions, electronics can react to various situations. The sensors primarily check variables such as the rotational speed of all four wheels, the vehicle's longitudinal and lateral acceleration, and the steering angle. By evaluating sensor data, the system can quickly adjust the drive force distributed to the front axle to achieve optimal steering. If the rear wheels tend to slip during acceleration, the system transmits a greater proportion of the drive force to the front axle via the further engaged multi-plate clutch. At the same time, ASR also prevents rear wheel slippage. When cornering, the front wheels receive only enough drive force to prevent lateral instability. On uneven roads, the rear differential equipped as standard on four-wheel drive models works with ABD to further improve traction.
In this way, PTM works closely with Porsche Stability Management to ensure perfect distribution of drive power at all times.
PTM works best on slippery or icy roads, where the vehicle's acceleration capabilities are astounding.
The result is a high level of safety and outstanding dynamics that can be applied in the most intelligent way.