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05 – Espace technique

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Aéro actif pour l’arrière des Porsche de demain

Porsche active diffuser patentPorsche travaille l’aéro de ses voitures depuis déjà bien longtemps. Avant même de surprendre le monde de l’automobile …

Active Balance

The Porsche Dynamic Chassis Control Sport (PDCC Sport) in the new Panamera.

Les ouvrages pour travailler sur votre Porsche

Total 911’s trio of top Porsche 911 suspension upgrades

Stop, turn, go. At its most fundamental, improving the performance of your Porsche 911 is a pretty simple, three-stage process. A few weeks ago, we covered the ‘stop’ element with our selection of brake upgrades; now it’s time to ‘turn’.

We’ve put together a trio of damper options (plus a chassis tuning extra) to help you get the best from your Porsche 911 when you face it with a few corners:

Öhlins Road & Track dampers – from £1,800 each plus VAT
Ohlins damper

Formed 40 years ago, Swedish suspension supremo Öhlins is one of the best damper manufacturers in the world. Their Road & Track range uses their decades of motorsport success to create potentially the best road car dampers around.

Available for most 996 and 997 models (997.1 GT3 RS pictured), they feature a lightweight aluminium construction and are fully adjustable, with threaded spring platforms and independent bump and rebound adjusters.
rpmtechnik.com

Bilstein Sports B6 front dampers – £169.05 plus VAT
Bilstein damper

Don’t think that suspension upgrades are the sole preserve of later Neunelfers. The Bilstein Sports B6 range allows for classic Porsche 911s to benefit from a performance-orientated dynamic without compromising on the everyday usability of needing to lower the stock ride height.

The pictured damper is for a 1985 Carrera 3.2 with Boge struts, however, versions for all 911s from 1965 to 1989 are available.
design911.co.uk

EuroCupGT dampers and top plates – £995 plus VAT
EuroCupGT damper

EuroCupGT may not be a name familiar with everyone, especially when it comes to suspension – however, this British company certainly has form in the damping department, helping to develop coilovers for the World Touring Car Championship in 2005.

Allowing damping and ride height adjustment, the EuroCupGT damper kit fits all non-PASM water-cooled Porsche 911s up to second-generation 997s. The price includes top plates and springs.
porscheshop.co.uk

EuroCupGT adjustable top plates – £375 plus VAT
PorscheShop top mounts

For those wishing to retain their Porsche 996 or 997’s original factory dampers, EuroCupGT’s top mounts allow you to adjust your car’s camber, ensuring that your tyres are performing to their maximum potential on track or road.

CNC machined from billet aluminium, the top plates include stainless steel bushings and aerospace quality monoballs and are available for Carrera, Turbo and GT3 models.
porscheshop.co.uk

Porsche Stability Management: Instability control

Taking it to the limit, safely and surely: The new Sport mode in Porsche Stability Management helps ambitious Porsche drivers reach the very limits of vehicle control—and the pinnacle of driving pleasure.

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Technology explained: Electrical power-assisted steering

First introduced on the 964 in 1989, the Porsche 911’s power steering has traditionally been hydraulically assisted. This system forces fluid to help turn the steering thanks to pistons within the rack itself. The fluid is pressurised by an engine-driven pump.

Moving to the 991, Porsche changed to a fully electric-assist system developed in conjunction with ZF. The new system uses an electric motor, mounted on top of the rack, to help force the steering around when the steering wheel is turned thanks to a second pinion gear.

Compared to the hydraulic system, the 991’s EPAS is much simpler, removing the need for an engine-driven pump and the rear-to-front plumbing needed to force the pressurised fluid to the steering rack.

Moreover, the electric motor doesn’t use any power from the engine, improving efficiency, while the whole system also saves weight over the 997’s power steering.

Porsche 991 steering wheel

Rather than calculate the required assistance from the driver’s input though, Porsche’s EPAS uses the myriad information garnered through the various steering and wheel sensors to provide the necessary assistance.

The result is a rack which can constantly vary the level of assistance provided and, through tuning the system’s software, can increase steering weight when sports modes are activated.

The new EPAS also filters out a lot of high-level feedback frequencies, especially around the dead-ahead steering position. This makes the car smoother to drive, as it is easier to keep the car travelling in a straight line without the necessity to correct for every small bump and camber in the road surface.

Our online ‘technology explained’ features are the perfect way to brush up on Porsche’s increasingly complex engineering. Read them all here.

Seven reasons PDK is better than manual

It’s the perennial debate: what’s the better transmission for your Porsche 911, PDK or the old-fashioned manual shifter? PDK sales are currently usurping the manual choice across the 991-generation’s Carrera range (as it’s currently the only 911 where you’re even given the choice) and for good reason, too. Of course, those who hail from the draconian era of automotive operation will invariably battle fiercely in favour of the manual, yet they are quite obviously (and ever so humorously) wrong. Here’s seven of the best reasons why:

 

1) PDK is faster

Porsche’s double clutch (which is quite literally what ‘doppelkupplung’ translates to) gearbox can switch gears in less than 100 milliseconds. With even the best will in the world, that’s a figure that’s never going to be challenged by a manual shift in a competition-spec sequential ‘box, let alone on a road-going sportscar. Changing gears quickly means keeping drive supplied to the wheels, which propels you up the road faster. In a car such as the 911, which has track capabilities in mind, this is a good thing. A very, very good thing.

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2) PDK is more economical

Like it or not, we have to care about the environment these days (it’s why Porsche is having to adopt turbocharged engines for the 911 in the autumn, after all). With that in mind, PDK is again the winner: the car’s intelligent ECU is adept at saving fuel and eeking out MPG while not taking too much away from the driving experience, even if that does mean Carreras now have that annoying coasting function jumping into play as soon as the driver jumps off the accelerator pedal. Having a better MPG means you don’t have to visit the petrol station as much, which means you’re using less fuel today, which in turn means more fuel will be around for longer, enabling you to continue using your pride and joy on the road long after your 991 is considered a ‘classic’.

 

3) PDK promotes longevity in a sportscar

Nobody wants to buy a used 911 with battered teeth on the transmission cogs through missed gear changes. Even worse, nobody wants a GT3 with a documented history of over-revs (a quick plug-in and you’ll be able to check these days, remember). PDK eliminates these grave problems rather nicely. It means you can sell your 911 with confidence when the time comes, and if you’re on the other end of the bargain, you can buy with confidence that your expensive transmission is in rude health, too.

 

4) PDK makes performance cars useable day-to-day

Ever tried driving a high-powered performance car around town and winced at the weight of the pedal every time you’ve tried to deploy the clutch? Again, PDK eliminates this, making high-powered 911s such as the Turbo, Turbo S and GT3 useable day-to-day. You’ll have to give that left thigh a workout elsewhere.

 

5) PDK is still engaging

Believe it or not, you can still have fun in a 911 equipped with PDK. Simply use the paddles (on a Sport Design wheel) to keep the super-quick 991 Turbo or Turbo S in it’s impressive torque band, or get the left peg involved in using the brake pedal for even quicker driving. Carrera Cup drivers still have fun competing without a manual shifter for company, so you should be fine, too.

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6) PDK is simple

PDK means no more missed gears, which is quite an achievement in the seven-speed manual 991. Also, Porsche has (perhaps deliberately?) muddied the experience of the manual gearbox in 991s by making the driver constantly battle across clunky gates, with an overtly weighty throw on C4 models. With PDK, you can still enjoy ‘manual’ mode, using the shifter like a sequential ‘box, pulling it ‘to’ for change ups and ‘away’ for lightning-quick change downs in a GT3. Remember though, it’s the other way around in Turbo/Carrera models.

 

7) PDK is the future

Quite simply, the days of the manual shifter are numbered. As I’ve already mentioned, even the Carrera Cup and Supercup drivers have done away with the manual gear shifter, and the road cars are the spiritual essence of these track-focused thoroughbreds. Sure, the manual transmission is fun in a traditional, romanticist automotive manner, but technology has evolved and it is us who must also evolve with it.

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Do you agree? Comment below or tweet us @Total911 with your thoughts.

Technology explained: Carburettors

From the Solex of pre-1967 cars, to the Webers of early 911Ss and Zeniths of later 911Ts, the air/fuel mixture in Porsche’s early flat six engines was fed into each cylinder by a pair of three-choke carburettors.

A carburettor’s job is to mix together air and fuel before it is pulled into the cylinder during the intake phase of the internal combustion cycle. Making use of the Bernoulli principle (the same scientific tenet that explains how an aerofoil creates lift/downforce), the inside of a carburettor is shaped like an hourglass, with a narrow section at its centre creating a venturi.

At this narrowing, the air travelling through the carburettor is forced to speed up. When this happens, thanks to the Bernoulli Principle, the higher velocity air creates a low-pressure zone, forcing a vacuum effect that draws petrol out of the float chamber, through a jet and into the intake tract of the carburettor.

Airflow through a traditional carburettor is controlled by two butterfly valves. On a downdraft unit, where air flows in from the top-mounted velocity stacks as per a Porsche 911, the uppermost butterfly valve, mounted about the venturi, is the choke.

911S Weber carburettor

This is used to prevent airflow during cold starts when engines need a rich mixture (more fuel per unit of air) in order to start. However, in all carburetted 911s, the choke is removed, simply leaving the throttle butterfly valve mounted below the venturi and main intake jet.

Whenever the intake valves in the cylinder head opens, the suction created by the downward movement of the piston, sucks air into the top of the carburettor.

As the throttle pedal is pressed, the valve inside the carburettor rotates, increasing allowing more air to flow through the venturi, sucking in more fuel from the float chamber.

Mounted to the side of the carburettor’s body, the float chamber is a reservoir filled with fuel, from which the petrol is sucked into the venturi. The chamber’s name comes from the float that is used to control the level of fuel stored inside the reservoir. As the float drops, it pulls down on the float arm, opening up a float valve. Fuel can then be fed into the float chamber via the pressurised fuel line.

Carburettors were a simple mechanical system for mixing fuel and air however, Porsche quickly began phasing them out in favour of mechanical fuel injection in a move designed to improve throttle response.

Our online ‘technology explained’ features are the perfect way to brush up on Porsche’s increasingly complex engineering. Read them all here.

Weber carburettor

Technology explained: Direct Fuel Injection

In a traditional petrol injection engine, fuel is injected into the intake manifold where it mixes with air. This air-fuel mixture is then transferred into the combustion chamber when the intake valves open.

This basic fuelling principle has been used on Porsche 911s since the introduction of the ‘E’ in 1968, the first road-going offering from Zuffenhausen to feature Bosch fuel injection.

For the second-generation 997 though, Porsche made the move to direct fuel injection (DFI), the first major revision to the sports cars injection technology in 40 years. DFI, as the name suggest, injects the petrol straight into the combustion chamber, leaving pure air to be fed through the intake manifold.

DFI technology first made it onto the second generation of Porsche 997 Carrera.

By injecting petrol directly into the cylinder (at pressures up to nearly 2000psi) better homogeneity of the air-fuel mixture is achieved. This creates a leaner mixture than standard fuel injection, resulting in improved fuel economy.

Similarly, the cone angles of in the 9A1 engine’s multi-hole injectors have been specifically calculated to optimise torque, power output, fuel consumption and emissions. DFI is able to inject the fuel closer to the source of ignition (the spark plugs) producing a more even flame front.

Because of this, the fuel mixture is burnt more completely, increasing efficiency, reducing emissions and improving power output. DFI also enhances combustion chamber cooling, allowing greater compression ratios to be used, again resulting in increased efficiency and power.

The DFI flat six seen in 997.2 and 991 models (including Turbos and, latterly, the new GT3) is codenamed the 9A1.

Injecting the fuel straight into the combustion chamber allows the DFI system to engage multiple injector pulses during a single combustion phase. In the 9A1 engine, Porsche utilises up to three pulses during cold starts and high engine loads, the former to speed up catalytic converter heating, the latter to optimise torque.

The engine management system is able to individually regulate the injection timing for each cylinder in the flat six, while the injection rate for each bank can also be controlled.

To make sure that the fuel is being burnt as efficiently as possible, emissions are monitored by Lambda sensors in the exhaust system which feed back to the control unit, allowing for accurate adjustments to be made to the mixture.

Our online ‘technology explained’ features are the perfect way to brush up on Porsche’s increasingly complex engineering. Read them all here.

Technology explained: Porsche Active Aerodynamics

After amateur racer Michael May mounted an inverted aerofoil onto his Porsche 550 racer in 1956, wings became a common sight in Formula One in the Sixties. Since then, the importance of downforce has played a key role in automotive design.

Downforce is created using an inverted aerofoil to split airflow through two paths (either traveling over the longer bottom side or the shorter top edge of the aerofoil). The air taking the top route travels slower than the air underneath the aerofoil.

This creates a high-pressure zone on top of the wing, with a low-pressure area formed on the underside. The difference in pressure pushes the wing towards the ground from above and sucks the underside down (like a wing)

The Porsche 991 Turbo's front spoiler in 'Normal' mode.

Increasing the wing’s angle of attack accentuates the difference in airspeed over the two sides of the aerofoil. However, downforce brings with it an increased drag coefficient, reducing fuel efficiency and top speed.

In order to counter this, Porsche has developed PAA for the 991 Turbo in order to have the best of both worlds. Below 120kph, the front spoiler and rear wing are fully retracted. However, as the car’s speed passes 120kph, the PAA system switches to the ‘Speed’ position,

This extends the outer two elements of the pneumatically-controlled, three-part front spoiler, reducing front-end lift. Furthermore, the rear wing extends by 25mm in order to maintain the aerodynamic balance. This mode is ideal for high-speed cruising.

The Porsche 991 Turbo's rear wing elevated to the 'Speed' position.

The PAA system’s third setting – Performance – is designed for maximum grip. In this position, the entire front spoiler is fully extended, while the rear wing is raised to 75mm and angled at seven degrees to horizontal.

At 300kph, the 991 Turbo can produce 132kg of downforce, allowing it to lap the Nordschleife two seconds faster than in the normal mode.

Our online ‘technology explained’ features are the perfect way to brush up on Porsche’s increasingly complex engineering. Read them all here.

Fully extended, this is the 991 Turbo's front lip in 'Performance' mode.

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