2008 Saab 9-3 Turbo X - Global - Press Release

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2008 TURBO X CELEBRATES THREE DECADES OF SAAB TURBOCHARGING LEADERSHIP AND INNOVATION

The 2008 Saab Turbo X high-technology model celebrates Saab’s 30 years of leadership in putting turbocharging on the automotive map. It all began in the fall of 1977, when the first Saab 99 Turbo model was presented to the world media.

At that time, Saab was alone in pursuing turbocharging as a reliable and realistic means of extracting more power and efficiency from a production engine. Saab’s success over the next three decades shows that imitation is, indeed, the sincerest form of flattery – today there few manufacturers who do not offer turbocharged models.

Turbocharging is even more seductive today than it was three decades ago . It is the key to what Saab calls “rightsizing;” proving that less is more. A turbocharged engine is typically lighter, smaller and more fuel efficient than a non-turbo, naturally-aspirated engine capable of producing similar power. Not only that, a turbocharger develops more power by harnessing the energy from an engine’s exhaust gas flow – and the notion of recycling energy that’s otherwise wasted is even more compelling.

Something for nothing

The idea that less is more is intrinsic to the minimalist tradition of good Scandinavian design. Decoration and ornate detail can sometimes distract from an appreciation of form, line or shape. While this Scandinavian perspective is very much part of Saab car design, the less-is-more philosophy can be even more closely identified with Saab’s mastery of the art of turbocharging.

While many engineers will claim that getting something for nothing is not a realistic expectation in engine design, most will agree that about 30 percent of the energy released when an engine burns fuel goes out the exhaust pipe. In other words, it’s wasted energy. A turbocharger, however, uses that energy to force more air into the engine. Correspondingly, some more fuel has to be added when extra air is pumped in, but a turbo gives the driver a choice in the matter.

As Saab’s leading turbo expert, Dr. Per Gillbrand, often known as the “father of the production turbo,” often said: “A turbocharged powerplant is really ‘two engines in one.’ There is a ‘small’ engine for driving in everyday traffic conditions and then a ‘large’ one, giving more power and performance, when the turbocharger joins the party at higher throttle openings.”

An industry leader

Today, Saab remains at the forefront of turbocharging technology. In a world seeking to reduce carbon dioxide emissions from fossil fuels, Saab BioPower engines bring together turbocharging and bio-ethanol (E85) fuel to drastically reduce those emissions – while also producing more power than is possible with gasoline. It is a smart, win-win solution.

In 1977, the skeptics were more concerned about turbocharging being a winning solution in terms of just power. Early attempts at controlling boost pressure produced adverse reliability issues that discouraged other manufacturers from further development for road-going production cars. But Saab, driven forward by the independent mindset of its engineers and executives, remained convinced that it could be done.

The company was able to draw on experience from aircraft design, where turbochargers were commonly used in aero engines to compensate for the effects of thin air at higher altitudes. It also shared knowledge with colleagues in what was then the company’s truck division, who were using turbochargers with large, heavy-duty diesel engines.

Challenging conventional wisdom

Saab developed technology to tame the turbo by using a bypass valve to control the build-up of boost pressure. It did not take long for the world to appreciate what had been achieved. Fitting a turbocharger to the 2.0L engine of a Saab 99 gave 23-percent more maximum horsepower and a massive 45-percent increase in torque. To produce similar power ratings, a naturally aspirated engine of the time would have been up to 50-percent larger in capacity and about 110 pounds heavier, with overall fuel consumption 30-percent greater. Saab has changed conventional wisdom that equated engine power with engine size.

An early Saab 99 Turbo road test in the UK’s influential magazine Autocar concluded: “It is not just its performance, but the way it delivers it. Its acceleration pattern is unique. Like a roller coaster running downhill, the Saab just gets faster as the turbocharger boost increases. It’s uncanny.”

Over the years, Saab has continued to refine the art of turbocharging – the roller coaster ride remains, but it is more comfortable. Advances in engine management systems and turbocharger design have given today's Saab turbo engines a much smoother and more progressive power delivery. The new, 2008 Turbo X, for example, delivers exceptionally strong pulling power of 295 lb.-ft. from very low engine revs, the characteristics of a far larger engine.

Rightsizing

As long ago as 1992, Saab was able to demonstrate the abilities of its Trionic engine management system (Generation 8 is used today) by arranging an independent car test in London traffic. It showed that levels of regulated pollutants in the Saab’s exhaust were actually lower than found in the surrounding atmosphere. The car was, effectively, “cleaning” the urban air.

Today, when the desire to save energy and achieve greater efficiency has never been greater, the future of Saab turbocharging has never been brighter. “Rightsizing” is how Saab describes the process of making engines more efficient; and reducing their size, weight and environmental impact without losing performance – showing that less is more.

Turbocharging also is a key component, combined with sophisticated engine management, “lean burn” technologies and the potential use of biofuel, such as Saab BioPower and E85 bioethanol.

Back to Saab turbo pioneer Dr. Gillbrand, who shared a similar philosophy when it came to efficient engine design: “All engines have an oil pump, a fuel pump and a water pump – so why not an air pump, which is all a turbo really is. It's odd that all engines don’t have one.”

Thanks to the power of such independent thinking, an increasing number of automotive engines are equipped with these efficient power builders.

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SAAB XWD ‘CROSS WHEEL DRIVE’: WORLD’S FIRST APPLICATION OF INNOVATIVE HALDEX 4.0 AWD SYSTEM

Developed in Sweden with Haldex of Stockholm, the Saab XWD “ Cross Wheel Drive” system is designed to optimize vehicle handling and stability in all driving conditions. It is offered in the 2008 Saab Turbo X and Aero versions of the 9-3 Sport Sedan and SportCombi, in combination with an uprated, 280-horsepower (206 kW), 2.8L V-6 turbo engine that now delivers almost 15-percent more maximum torque (295 lb.-ft. / 400 Nm) to exploit the greater traction available. It is paired with either a six-speed manual or six-speed automatic transmission.

This state-of-the-art all-wheel drive system includes two innovative features: pre-emptive engagement of the rear wheels to optimize traction at take-off; and an active rear limited-slip differential (eLSD), allowing variable torque transfer between the rear wheels.

Saab XWD is a fully automatic, on-demand system capable of sending up to 100 percent of engine torque to the front or rear wheels, whenever necessary. While offering drivers of Saab Turbo X and 9-3 Aero XWD sure-footed handling in low-grip conditions, the system’s sophisticated operation also enhances the sporty driving experience in all road conditions. Fine balancing of the drive torque between the front and rear axles raises the threshold at which ESP throttle and braking interventions are triggered, providing more scope for closer driver involvement.

The XWD system is governed by its own electronic control unit, which functions in harness with the engine, transmission and ABS/ESP control modules. The hardware consists of a power take-off unit (PTU) in the front final-drive that transmits engine torque through a prop shaft to the rear drive module (RDM). This incorporates a torque transfer device (TTD) and an electronically-controlled limited-slip differential (eLSD). Both are wet, multi-plate clutch units from Haldex.

At take-off, the TTD is initially activated when the clutch plates are forced together under hydraulic pressure, thereby engaging the RDM. This pre-emptive function is a valuable improvement in current technology, which requires the detection of wheel slip before the TTD is activated. For the driver, the enhanced functionality gives maximum traction immediately for smooth, strong acceleration from rest without the possibility of any initial hesitation.

On the open road, drive torque is seamlessly and continuously varied between the axles by the control of a valve in the TTD, which increases or reduces the pressure on the wet clutch plates. When cornering, Saab XWD rewards the driver by providing enhanced, more finely balanced chassis dynamics. Data from the vehicle’s ABS/ESP sensors – measuring wheel speed, yaw rate and steering angle – is analyzed, and Saab XWD enables the application of rear drive to balance oversteer and understeer characteristics, improving stability and roadholding.

In highway cruising conditions, when traction or optimum grip is not an issue, only 5- to 10-percent of engine torque is typically transmitted to the rear wheels. This helps provide a greater measure of stability, while helping to save fuel.

The ultimate ‘icing on the cake’ with Saab XWD is the eLSD. It represents the first application of an electronically controlled, rear limited-slip differential in the segment. The eLSD is installed alongside the RDM and operates via pressurized clutch plates on a principle similar to the larger TTD. In icy or wet split-friction conditions, for example, it uses inputs from the rear wheel speed sensors and can transfer up to 40 percent of torque between the drive shafts, to whichever wheel has more grip.

The eLSD also gives the driver enhanced control when cornering hard or completing a high-speed maneuver, such as a lane change, by momentarily applying more or less torque to either of the wheels to help the rear of the car more closely follow the direction of the front wheels. This yaw damping effect can keep the car better balanced and more tightly controlled, without requiring “outside” intervention from electronic stability aides.

Installation of Saab XWD includes the fitment of a new rear sub-frame to carry the RDM, revised rear suspension geometry and new wheel hubs for the drive shafts. The three-piece prop-shaft runs through two bearings with constant velocity joints for smooth running with minimal “wind-up.” Wheelbase and rear track dimensions are unaltered. All Saab Turbo X and 9-3 Aero XWD Sport Sedan and SportCombi models will have 18-inch alloy wheels as standard equipment.