Print Español

How It Works


HOW IT WORKS




DIRECT FUEL INJECTION

With millisecond accuracy, DFI injects fuel at a pressure of up to 1740 psi directly into the combustion chamber by means of electromagnetically actuated injection valves.

The spray and cone angles have been optimized for torque, power output, fuel consumption and emissions by enabling a homogeneous distribution of the air/fuel mixture, and, therefore, effective combustion. With direct injection, the EMS SDI 3.1 engine control regulates injection timing individually for each cylinder as well as the injection rate for each cylinder bank. This optimizes the combustion process and fuel economy. A hot-film  air mass meter takes care of the airflow, so that the combustion chambers contain exactly the right mixture at all times.
At up to 3,200 rpm, the engine operates with dual injection; at up to 2,500 rpm, it even works with triple injection. The required volume of fuel is distributed between two or three sequential injections, respectively - for faster heating of the catalytic converters after a cold start and for greater torque in the upper load range.

DFI improves the internal cooling of the combustion chamber by having the mixture prepared directly in the cylinder. This allows for a higher compression ratio (12.5:1) which helps to deliver more output along with enhanced engine efficiency. It has therefore been possible to reduce C02 emissions by up to 15% depending on the model.

Injection is regulated by the electronic engine management system. The exhaust gas cleaning system ensures that emissions remain well below even the strict limits of the EU5 emission standard, thus helping to protect the environment.



PORSCHE DOPPELKUPPLUNG (PDK)

The optional Porsche Doppelkupplung (PDK), with both manual gearshift and an automatic mode, enables smooth gear changes with no interruption in the flow of power. This results in significantly faster acceleration and lower fuel consumption, without having to sacrifice the ease of automatic transmission.

In total, PDK has seven gears at its disposal. Gears 1 to 6 have a sports ratio and top speed is reached in 6th gear. The 7th gear has a long ratio and reduces fuel consumption even further.

PDK is like having two gearboxes in one and thus requires two clutches - designed as a double wet clutch transmission.

This double clutch provides an alternating , non-positive connection between the gearbox and the engine by means of two separate input shafts (input shaft 1 is nested inside the hollowed-out input shaft 2).

The flow of power form the engine is only ever transmitted through on clutch at a time, while the next gear is preselected by the second clutch. During a gear change, a conventional shift no longer takes place. Instead, one clutch simply opens and the other closes at the same time. Gear changes therefore take place within a few hundredths of  second.

Clutch 1 controls the odd gears (1, 3, 5, 7) and reverse. Clutch 2 controls the even gears (2, 4, 6).

The crankshaft trasmits engine torque to the dual-mass flywheel which is then channelled through the clutch housing and onto the multi-plate clutches, or to be more precise, the outer disc carrier.

Under oil pressure, clutch 1 closes and forms a frictional connection with input shaft 1. The torque is now transmitted through the differential to the rear axle or, in the all-wheel drive variants of the 911, the front and rear axles.

At this stage, PDK has already preselected the next gear. Engine torque is already acting on the other outer disc carrier and, in response to a gear change signal, the overlap shift is initiated, i.e. as clutch 1 opens, clutch 2 closes. The non-positive connection with input shaft 2 is established, and power is transmitted to the wheels. The gear which is engaged is displayed on the instrument cluster.

PDK has distinct benefits. The very rapid gearshifts, with no interruption in the flow of power, produce faster acceleration.

Driving feels even sportier and more dynamic, and agility is increased. Depending on the gearshift programme, the gear change is optimised for comfort or for sporty handling.

The compact dimensions of the gearbox reduce rotational masses which means a more direct engine response, and the system is more lightweight.

This, along with the long-ratioed 7th gear, helps to achieve reduced fuel consumption and emission figures comparable with those of a manual gearbox. In conjunction with the new engines, it has been possible to reduce fuel consumption by up to 13% and C02 emissions by up to 15%, depending on the model.

With the optional Sport Chrono Package Plus, PDK is enhanced by the 'Launch Control' and 'motorsport-derived gearshift strategy' functions.

Three-spoke sports steering wheel with gearshift switches:

In conjunction with the optional Porsche Doppelkupplung (PDK), the standard three-spoke sports steering wheel features two ergonomic switches.

One press with the thumb and PDK shifts up. One pull with the index finger and PDK shifts down. Either the right or left hand can be used.

Gear selector for Porsche Doppelkupplung (PDK):

The gear selector for PDK is ergonomic and designed for high functionality, enabling you to change gear manually. The control concept mirrors the logic of the paddles on the three-spoke sports steering wheel - press forwards to shift up, pull backwards to shift down.

Even if the gear selector is set to automatic mode, you can still change gear manually using the paddles on the steering wheel.


 
Porsche Traction Management (PTM)

In a 911, engine power is not the only priority. There is always the question of how this power can be effectively and consistently delivered on the road. One solution to this is all-wheel drive. An even better one is intelligent Porsche Traction Management (PTM), comprising permanent all-wheel drive with an electronically controlled multi-plate clutch, an automatic brake differential (ABD) and anti-slip regulation (ASR).

Previously exclusive to the 911 Turbo and now available as standard on the 911 Carrera 4 and 911 Targa 4 models with all-wheel drive, the force between the front and rear axle is no longer distributed by a viscous multiple-disc clutch, but actively by an electronically controlled multi-plate clutch.

In comparison with a viscous multi-plate clutch, where clutch regulation is not initated until there is a difference in speed between the front and rear axles, the electronically controlled multi-plate clutch responds much more rapidly. Though continuous monitoring of the driving conditions, the electronics are able to respond to a variety of situations. Sensors check, among other variables, the rotation speeds of all four wheels, the longitudinal and lateral acceleration of the vehicle, and the steering angle. By evaluation the sensor data, the system can quickly adjust the distribution of drive force to the front axle in order to achieve optimum balance. If the rear wheels threaten to spin under acceleration, a greater proportion of drive force is sent forwards by a more powerful engagement of the multi-plate clutch. At the same time, ASR prevents the rear wheels from spinning. When cornering, the front wheels only ever receive as much drive force as is necessary to prevent lateral instability. On uneven surfaces, the rear differential fitted as standard to all-wheel drive modes, in combination with ABD, also improves traction.

In this way, PTM, in conjunction with Porsche Stability Management, ensures that the perfect distribution of drive is achieved every time.

PTM really comes into its own in the wet or in the ice and snow. In these conditions, the car's acceleration capability is simply breathtaking.

The result: a high level of safety and outstanding performance. Put to use in the most intelligent way.