Porsche Boxster (2008)
As the spiritual descendants of the legendary 356 Speedster and 550 Spyder, the Porsche Boxster and Boxster S carry the company's torch of affordable, open-top driving excitement. After receiving power boosts last year, the mid-engine roadsters go into 2008 with minor refinements.
Efficient mid-engine roadster configuration
As proper roadsters, the Porsche Boxster and Boxster S have been designed to accommodate two people and a modicum of cargo in a small, agile, open-top, and powerful sports car. As part of the Porsche family, the Porsche Boxster and Boxster S have their six-cylinder horizontally opposed engines mounted behind the passenger cabin. In fact, the chassis is a true mid-engine design for the optimum balance needed for superb road holding and response.
Both Porsche Boxster and Boxster S share a hot-galvanized all-steel body on a monocoque structure. The Boxster roadster's low, lithe body has a coefficient of drag of just 0.29 when equipped with manual gearbox, 0.30 with Tiptronic S. The Porsche Boxster S, with its wider wheels and tires, has a Cd of 0.30 in manual trim, 0.31 with Tiptronic S. Among the cars' aerodynamic attributes is the combination of high-speed stability and superior drivetrain and brake cooling.
The engine radiators are cooled via two large air inlets in the front air dams. The Porsche Boxster relies on two radiators, and the Boxster S on three. A lightweight, high-capacity water pump moves the coolant so efficiently that Porsche engineers were able to specify a smaller, lighter oil cooler than otherwise, helping maintain the cars' low weights.
Airflow beneath the body is directed to the transmission by flexible underbody blades. In addition, small spoilers on the front suspension's longitudinal arms keep the brakes in a steady stream of air for enhanced cooling.
Though sharing familiar Porsche design cues, the Porsche Boxster and Boxster S clearly look like no other vehicles on the road and are distinct from other Porsches.
In front, though the headlamps have the traditional Porsche look, the foglamps are separate and positioned low and away from the car's centerline for a broad arc of light regardless of conditions. The rear lights are broken into three separate elements on each side of the car, with clear demarcation between the elements.
Convenient cargo carrying, front and rear
The mid-engine design allows for a versatile trunk aft the engine. In 2007, Porsche engineers repositioned the service tray, giving that trunk a more symmetrical shape. This modification smoothed the right trunk wall. Though trunk capacity is essentially unchanged at 4.6 cu.-ft. (130 liters), the space is more usable.
The service tray allows ready access to the engine-oil filler neck and the coolant expansion tank. This refinement was made possible by moving the coolant tank into the engine compartment, allowing both the coolant and oil fill caps to be repositioned.
The rear trunk is complemented by the front luggage compartment which has a 5.3 cu.-ft. (150 liter) capacity.
Folding top is lightweight and compact when stowed
The soft top of the Porsche Boxster and Boxster S is power operated at the touch of a button. And since Porsche engineers understand full well that conditions can change suddenly, the top can be operated even when the car is moving at speeds up to approximately 30 mph.
The canvas roof has a lightweight, synthetic fleece fiber for added noise reduction and weather insulation. The glass rear window is electrically heated to defog it as necessary. The top's frame is constructed of magnesium and aluminum to keep its weight down. And the car's center of gravity is kept low thanks to the fact that the folded top stores below the car's beltline. Yet, the folded convertible top does not rob any of the car's storage area.
A wind deflector is available to reduce passenger cabin turbulence during top down driving. A removable aluminum hardtop that weighs only 51 pounds (23 kg) is also available.
New exterior color choices
Besides the addition of Macadamia Metallic to the exterior colors palette there are several refinements. Atlas Grey Metallic is now a special color, replacing Lapis Blue Metallic, Malachite Green Metallic replaces Lagoon Green Metallic, and Carmona Red Metallic is replaced by Ruby Red Metallic. Gone from the choices of interior color is Palm Green.
Enhancements to the interiors of the 2008 Porsche Boxster and Boxster S give the cars a cleaner, more aesthetic cockpit and the option of truly high-performance driving seats.
A new optional natural leather choice is Carrera Red. As before, the gearshift, steering wheel rim and handbrake lever, as well as the seats, are leather covered. In addition, the Porsche Boxster S also has a leather covered center console storage box cover and leather covered door pockets.
The interior door panels, center console sides and dashboard are finished in a durable material, specially made for them. The trim around the gearshift lever and air vents has an aluminum look. For 2008, the air vents are now soft-touch matte black replacing the previous Volcano Grey.
Clear, quick reading instruments
The instrument cluster is dominated by a large tachometer flanked by two slightly smaller gauges. For instant reading, the car's road speed is shown both in analog and digital form. For optimum readability, the Boxster's gauges are black and the Porsche Boxster S has light grey gauge faces. White LED readouts maximize ease of reading the gauges in low-light conditions.
Additionally, cars equipped with the Sport Chrono (Plus) system display information in the dot matrix display in the lower third of the rev counter.
For added convenience, the Porsche Boxster has a separate, additional 12-volt power outlet on the passenger's side of the center console. Two hidden cupholders are mounted behind a trim panel, popping out when needed.
Choice of steering wheels
Driver comfort and control are both enhanced by the standard adjustable steering column in both Porsche Boxster and Boxster S. The steering columns both tilt and telescope. The steering column has a tilt range of 1.57 inches (40 mm) at the steering wheel.
Buyers may select from among three different steering wheels. The three-spoke design standard steering wheel is 14.76 inches (375 mm) in diameter and has a composite magnesium core. This wheel is lighter than the former aluminum-frame wheel.
A smaller optional sports wheel has a14.57-inch (370 mm) diameter and a rim with contoured recesses for better control during dynamic driving.
A third steering wheel is available with the optional Porsche Communication Management system. This steering wheel has buttons to operate the telephone as well as the audio and navigation systems.
Abundant seating choices
Among the seat options for 2008 are newly available sports folding bucket seats. These optional seats are essentially race seats that are perfectly comfortable and safe for everyday use. With folding backrests and integrated thorax side-impact airbags, the sports bucket seats meet all current federal safety standards. However, by dint of their carbon fiber-reinforced construction, the seats save 15 to 20 pounds (7 to 9 kg) over standard seats, depending on the seat.
The standard leather buckets offer power adjustable backrests with manual fore-aft and height adjustment. Buyers can also opt for full-power leather upholstered seats with pneumatic lumbar support compliments of two inflatable air cushions. The driver's seat offers memory setting.
For those wanting more support than the standard seats but not the extremely deep contours of the new sports bucket seats, the Porsche Boxster and Boxster S may also be equipped with sports seats based on the standard units, but with added lateral support on both seat cushion and backrest.
Optional adaptive sport seats offer full power adjustment of the seats' side bolsters.
All seats in the Porsche Boxster and Boxster S are mounted low for optimum head room and low center of gravity. In addition, the seats benefit from a Porsche-patented vibration dampening system.
Open-top occupant protection
Realizing that crash protection is even more critical for occupants in an open-top car than in a steel-roof one, Porsche's engineers equipped all Porsche Boxster roadsters with three-point inertia-reel seat belts with belt-latch tensioners and belt-force limiters as well as six airbags.
In addition to two-stage frontal airbags, the Porsche Boxster and Boxster S feature the Porsche Side Impact Protection (POSIP) system with torso-protecting thorax side-impact airbags mounted in the outer edges of the seatbacks and special head-protecting side-impact airbags which deploy from the doors' windowsills.
The frontal airbags benefit from the use of an organic-based propellant which reduces their needed storage space and their weight, while also easing their recyclability.
To protect small children, the passenger seat sensors automatically defeat the passenger front airbags if the sensors detect a lightweight occupant.
Both Porsche Boxster and Boxster S ride on fully independent suspensions. The front and rear suspensions are of Porsche-modified McPherson strut configuration, with trailing links and twin-tube gascharged shocks. In addition to the standard suspension, both Porsche Boxster and Boxster S offer Porsche Active Suspension Management (PASM) as an option. PASM offers the driver a choice of two basic shock settings, Normal and Sport.
At the core of PASM are continuously adjustable shocks, a front and rear accelerometer and a dedicated electronic control unit. The PASM controller receives data about the vertical movements of the car's body as well as steering angle, vehicle speed, brake pressure and engine torque.
The control unit then alters oil flow within the shocks to constantly provide the optimum firmness for the conditions and driver's desire. The system's active shocks have a similar structure as standard shocks but incorporate an electronically controlled internal bypass valve that increases or reduces oil flow as needed.
Intelligent damping control
More than merely a two-setting suspension, PASM automatically adjusts to the driver's style. If left in Normal mode, PASM will gradually increase the suspension's firmness if the car is driven with greater enthusiasm, generating higher dynamic forces.
Rapid and sudden steering movements indicate to the control unit an immediate need to increase shock forces on both axles, to reduce swaying or rocking.
By monitoring vertical motions of the body, the system can firm the shocks in Normal mode as reaction to a rough road, minimizing rocking. However, in Sport mode the same motions alert the controller to reduce the shock absorbing forces to help ensure that the wheels to remain in contact with the road and optimizing ride comfort.
When the driver steps on the brakes, PASM firms the shocks to reduce body dive and, as the braking sequence continues, adjusts to softer shock absorbing, with different forces front and rear, to ensure solid tire to surface contact, even on broken pavement or rough roads, to minimize stopping distance.
PASM also controls body squat during full-throttle acceleration. As the driver may briefly lift off from the throttle during gear shifts, PASM instantly adjusts firmness at front and rear axles to compensate for the brief change in loads. In Normal mode, PASM increases shock absorbing to prevent excess squat. In Sport mode, the shock absorbing is softened to improve traction.
Stability is standard
Both the 2008 Porsche Boxster and Boxster S are equipped with enhanced Porsche Stability Management (PSM) as standard equipment. PSM is a computerized system that relies on data from an assortment of sensors to help maintain the car's intended path should the car be pushed to the edges of its dynamic limits. By comparing speed of the individual wheels, vehicle speed and engine speed, PSM can determine that the car may be beginning to slip sideways or that a tire is losing traction and beginning to spin.
To rein the car back under the driver's control, PSM applies individual brake force to a slipping wheel. If more drastic measures are required, PSM works with the engine control module to reduce engine power briefly. PSM is programmed to intervene less quickly when the car is moving below 45 mph (70 kmph) to allow the driver more latitude.
Unlike some similar systems, PSM can be switched off by the driver. When deactivated, the enhanced PSM remains off until the driver firmly hits brake pedal, reaching the ABS threshold on at least one front wheel. This allows the skilled enthusiast driver more dynamic freedom. PSM is non-intrusive, never letting the driver feel that the system is wresting control from him.
The Porsche Boxster and Boxster S come with standard variable-ratio rack-and-pinion steering. This both increases agility and stability at higher speed maneuvers and reduces steering effort at slow speeds.
When the steering wheel is within 15 degrees of center, the steering ratio remains similar to that used on the first-generation Porsche Boxster. This assures a smooth and calm driving experience, even on rough surfaces.
When the steering wheel angle exceeds 15 degrees, the steering is instantly more direct, reducing lock-to-lock and quickening response. This enhances control while driving quickly on winding roads and when moving slowly, as when parallel parking.
The Porsche Boxster has a tight turning circle of only 36.4 feet (11.1 meters).
Enhanced braking system
The Porsche Boxster and Boxster S are equipped with four-wheel disc antilock brakes. Both cars have cross-drilled rotors and four-piston monobloc aluminum calipers at all four wheels.
On the Porsche Boxster, front brakes are 11.73 inches (298 mm) in diameter and 0.94 inches (24 mm) thick while the rear brakes are 11.77 inches (299 mm) across and 0.79 inches (20 mm) thick.
The more powerful Porsche Boxster S gets even larger front brakes: 12.52 inches (318 mm) by 1.1 inches (28 mm) while the rear brakes are 11.77 inches (299 mm) by 0.94 inches (24 mm) thick.
Rather than rely on engine vacuum alone to provide brake assist, Porsche engineers equipped both the Porsche Boxster and Boxster S with a dedicated mechanically driven vacuum pump that supplies assist to the brake servo. Driven by the exhaust camshaft on the right-hand cylinder bank, the vacuum pump ensures a high and consistent level of braking assist, regardless of ambient air pressure or steady open-throttle driving.
Greater stopping power available
Those drivers of the Porsche Boxster S who desire even greater braking power than standard may opt for Porsche Ceramic Composite Brakes (PCCB).
Developed for the extreme use of motorsports, PCCB replaces the standard metal brake rotors with 13.78-inch (350 mm) ceramic discs. Besides delivering otherwise unobtainable levels of consistently superb braking performance under repeated heavy use, the ceramic rotors weigh approximately 50 percent less than iron ones. PCCB reduce the car's unsprung mass by 34.4 pounds (15.6 kg).
In their latest iteration, Porsche Ceramic Composite Brakes are more rigid than before while providing more interior cooling ducts. The newest brakes also have increased fiber reinforcement of the friction surface, significantly enhancing resistance to abrasion under high loads.
Multiple wheel and tire choices
The Porsche Boxster rides on standard 17-inch light-alloy wheels. The Boxster S comes with 18-inch wheels. Optional on either are 19-inch rims.
The Porsche Boxster comes with wheels that feature a forked, five-spoke design. Wheels are 6.5 inches wide in front and eight inches wide in the rear. All tires are Z-rated radials, 205/55 aspect in front and 235/50 in the rear.
The Porsche Boxster S is also on forked, five-spoke wheels of a different design than the Boxster. The front wheels are eight inches wide and the rears are nine inches wide. The Z-rated tires are 235/40 in front and 265/40 in the rear.
Four different 19-inch wheels are available as options, including a forged alloy tri-spoke wheel from the 911 Turbo. All optional front wheels are 8-inches wide; all rears are 9.5-inches wide.
No spare saves weight
To save 22 pounds (10 kg) and increase room for cargo, both the Porsche Boxster and Boxster S are equipped with an electric air compressor and emergency tire sealant. There are no spare tire, jack or tire-changing tools.
Porsche engineers know that correct inflation pressures are not just critical for safety, but also mandatory for exacting the full measure of a car's dynamics. Therefore both the Porsche Boxster and Boxster S come equipped with the Porsche Tire Pressure Monitoring System (TPMS) as standard equipment.
Sensors at each wheel monitor inflation pressure. If pressure falls by more than 2.9 psi but not as much as 5.8 psi, the driver is alerted. The warning comes in the form of a text message shown in the tachometer's digital display. The warning will appear each time the car is started and stay in the display for 10 seconds.
If air pressure falls by more than 5.8 psi, or if pressure drops by more than 2.9 psi per minute, the warning becomes more intense. The text is bright red. This warning appears as soon as the respective values are exceeded, whether the vehicle is stationary or moving.
More power from more efficient engines
Both Porsche Boxster and Boxster S continue in 2008 with the larger, more potent engines they received in 2007.
The Porsche Boxster is powered by a 2.7-liter horizontally opposed six cylinder that's almost as potent as the engine that was in the first Boxster S: 245 horsepower at 6500 rpm. The engine makes 201 lb.-ft. of torque over 4600 rpm to 6000 rpm. When mated to the standard five-speed manual gearbox, the engine propels the Porsche Boxster to 60 mph from a start in 5.8 seconds. When equipped with the Tiptronic S transmission, the Porsche Boxster gets to 60 mph in 6.7 seconds. Top speed at the test track is 160 mph (258 kmph).
The Porsche Boxster S carries a 3.4-liter flat six that develops 295 horsepower and 251 lb.-ft. of torque from 4400 rpm to 6000 rpm. That's enough to scoot the Boxster S from zero to 60 mph in 5.1 seconds when equipped with a manual gearbox and a blistering 5.8 seconds when equipped with the Tiptronic S. The Porsche Boxster S reaches a track-proven top speed of 169 mph (272 kmph).
Cleaner and more fuel frugal
Besides delivering more power than in their original iterations, the Porsche Boxster is now certified as an Ultra Low Emissions Vehicle (ULEV), and the Boxster S has earned a LEV-II (Low Emissions Vehicles, category two) rating.
And with EPA fuel economy ratings of 20 mpg in the city and 29 mpg highway for the five-speed Porsche Boxster, and 18 mpg city and 26 mpg highway for the Boxster S with manual gearbox, both cars deliver Porsche performance without the stigma of a gas guzzler penalty.
Both engines share a similar architecture. In fact, the key difference between the engines is displacement, as dictated by their different cylinder bores. While both share a 3.07 inch (78 mm) stroke, the Porsche Boxster engine has a cylinder bore of 3.37 inches (85.5 mm) and the Porsche Boxster has 3.78-inch (96-mm) diameter cylinders. In addition, the Porsche Boxster engine has a slightly higher compression ratio than the Boxster S: 11.3:1 vs. 11.1:1.
Otherwise, the engines both have aluminum blocks and cylinder heads. Both versions carry two overhead intake and overhead exhaust valves. The hallmark Porsche horizontally opposed cylinder configuration allows a low engine profile which contributes to the cars' low centers of gravity for stability and razorlike agility. Decades of Porsche racing experience allows the engineers to equip the engines with a dry sump lubrication system which ensures thorough engine lubrication even during the most extreme spirited driving while providing a compact engine package.
The engines also share Motronic engine management, six individual ignition coils and sequential fuel injection. And critically, both Porsche Boxster and Boxster S come standard with Porsche VarioCam Plus intake valve timing and lift control.
Attention to engine details
The 2.7-liter engine features a light crankshaft and the bores in the hollow piston pins are larger than before, saving six grams in each pin. This reduction in rotating mass helps give the engine its startlingly fast throttle response.
The Porsche engine designers also refined coolant flow around the exhaust valves in the 2.7-liter engine, reducing thermal loads which in turn reduce the chance of unwanted engine damaging detonation. This seemingly minor tweak to the casting process permits the raising of the engine's compression ratio to 11.3:1 compared with the larger engine's 11.1:1.
Since the external dimensions of the two engines are the same, they share the same variablelength intake manifold design. The manifold incorporates a resonance flap, and a double-chamber distributor pipe with a flap further downstream. The thresholds at which the flaps are moved are specific for the two engines, but the resulting high torque over a large engine-speed range is the same.
The distributor pipe (resonance length) and the resonance flap (resonance cross-section) are controlled as a function of engine speed. As long as the two flaps are closed, the two rows of cylinders draw their intake charge air separately from one another. The engine, in effect, acts like a double three-cylinder. This effect increases engine torque significantly at lower engine speed ranges.
Broad response thanks to variable valve timing
Engine response and efficiency are also enhanced through the use of Porsche VarioCam Plus adjustable valve lift and timing system. This valve management system adjusts intake valve lift and timing based on engine speed and load and is under the umbrella of the engine's main electronic controller.
Though the VarioCam Plus operates far too quickly for the driver to be aware of it, the results are obvious. The effect is that of an engine with two different intake camshaft profiles, one set up for smooth and efficient around-town driving, the other a high-performance camshaft designed for high-speed. These two designs usually each preclude the other and most cars have a compromise of the two. The VarioCam Plus removes the compromise and the driver benefits from the best of both driving worlds.
Valve timing is controlled via a vane cell adjuster which continuously varies the two intake camshafts positions relative to crankshaft. The adjustment range covers a 40-degree range of crankshaft angle. Valve lift is varied by a system utilizing two cup tappets, one resting in the other. These tappets are actuated by separate cam lobes of differing size. The engine control module directs oil pressure to the appropriate tappet based on engine speed and load parameters. When non-pressurized, the tappet moves under the camshaft lobe, but exerts no pressure on the valve, in effect free wheeling.
Integrated dry sump lubrication with three oil pumps
Given that the Porsche Boxster and Boxster S are designed to be driven quickly and enthusiastically, every element of the cars must withstand extended periods of high levels of lateral acceleration. Drawing from decades of racing success, Porsche engineers ensured the cars' engines would always be adequately lubricated, even under the most extreme driving conditions.
This is guaranteed by integrated dry sump lubrication that incorporate two re-delivery pumps which extract oil from the cylinder heads and pump it into the oil sump. From here, a pressure pump delivers oil to the lubricating points within the engine, the lubricant being cooled by a compact oil/water heat exchanger.
The integrated dry-sump system is so precise at monitoring oil levels that the engines have no engine oil dipstick. Instead, an electronic monitor measures the oil level and displays the result on the instrument cluster.
Shift gears or let them shift themselves
Buyers can choose either a manual gearbox or the Porsche driver- shiftable Tiptronic S automatic transmission in either Porsche Boxster or Boxster S.
Standard equipment in the Porsche Boxster is a five-speed manual gearbox. The Boxster S comes standard with a six-speed manual, which is optional on the Porsche Boxster. Both manual gearboxes have reinforced synchromesh rings on all gears.
To deal with the increased output from the 3.4-liter engine in the Boxster S, its standard sixspeed manual transmission is modified with shorter ratios for First and Second gears.
The five-speed features triple synchromesh on First gear and double synchromesh on Second. The six-speed has triple synchromesh on First and Second gears and double synchromesh on Third through Sixth gears. The First and Second-gear synchromesh rings have a wear-resistant carbon coating.
The Tiptronic S, which is optional on both Porsche Boxster models, is a five-speed that was revised in 2007. The transmission received new hydraulics and electronics as on the 911 series and Cayman S. The driver can either allow the Tiptronic S to operate as a fully automatic transmission, or use steering-wheel spoke mounted controls or the console-mounted shift lever, to up- and downshift for himself.
Sport Chrono Package Plus
The Tiptronic S offers greater performance for the enthusiast driver when utilized with the optional Sport Chrono Package Plus, available as an option on both Boxster models. The Sport Chrono Package Plus allows more aggressive control maps for the engine speed limiter, Porsche Stability Management (PSM), Porsche Active Suspension Management (PASM), and the Tiptronic S. The feature is activated by pressing a button on the center console. The package also includes a separate stopwatch gauge on top of the instrument panel.
When activated, the Sport light in the instrument cluster is lit. More importantly, the Tiptronic S is switched to manual mode and the electronically controlled throttle valve responds more quickly to input from the accelerator pedal. And if the driver's enthusiasm gets the better of him and he holds the accelerator down past the engine's redline, the speed limiter intervenes far more abruptly than otherwise. When the driver does shift gears, the changes are crisper than otherwise.
With the Sport Chrono Package Plus, agility is increased by changes to PSM operation. When accelerating, higher antispin control thresholds allow more slip from the rear wheels. Similarly, the antilock braking system intervenes later in the braking cycle than otherwise, permitting the skilled driver to brake deeper and harder into fast bends. The driver always has the option of deactivating PSM and taking total control of the car's dynamics.
On cars equipped with PASM, activating the Sport Chrono Package Plus provides firmer suspension settings, reducing even further any body lean through corners and enhancing contact between the tires and the road. However, there are circumstances, such as on wet or snowy roads, in which a softer suspension setting can enhance traction and the PASM button can be pushed to put the car in its normal setting even when the Sports mode is active.
The Sport Chrono Package Plus feature includes a stopwatch with lap-counting function. A steering column stalk allows the driver to record various route segment times, which can be reviewed graphically on the optional Porsche Communications Management (PCM) system screen.
Plethora of options
In addition to Sport Chrono Package Plus there are many options available for the Porsche Boxster and the Boxster S.
At the top of the list is the enhanced Porsche Communication Management (PCM). This boasts a DVD-based navigation system. The unit's DVD drive is remotely mounted in the luggage compartment which allows the dash-mounted CD drive on the PCM to be used exclusively for audio CDs, or MP3 encoded discs.
Available in conjunction with PCM is a multifunction steering wheel with redundant controls for audio, navigation and telephone functions. PCM may also be equipped with an electronic logbook that can record mileage, journey length, date and time as well as the starting point and destination address for any trip. Also optional is an extended navigation module that includes "back-trace" technology to allow a return to a starting point, even on roads not in the navigation system database.
While the standard four-speaker audio system has been refined, with the Porsche CDR-24 CD radio having a larger control surface illuminated by white LEDs. There are two audio options.
A 180-watt Porsche Sound Package Plus with an external amplifier is available. This sound system has seven speakers: two instrument-panel mounted tweeters and a dash-mounted midrange speaker as well as a subwoofer and midrange speaker in each door. For those wanting even more audio performance, there is a 325-watt Bose Surround System with a seven-channel digital amplifier and eleven speakers.
Other options include Bi-Xenon headlamps and Park Assist that uses ultrasound to measure the distance to the nearest detectable obstacle and warns the driver as needed.