Saab's Bold New Power Play

By Motoring Channel Staff - 27/05/2005

The Saab 9-3 Sport Sedan Aero with its new 2.8-litre V6 Turbo engine is, quite simply, the fastest accelerating car ever to carry the Saab badge, according to the Scandinavian automaker.

For the first time, Saab customers will be able to enjoy the combined benefits of turbocharged power and 6-cylinder refinement in a purpose-built package.

With GM at the helm, it is no longer content to let its European marque sit on the sidelines with meek vehicles - it wants a bigger piece of the prestige pie, and the new 6-cylinder turbo engine for the 9-3 Sport Sedan is the first step towards a more dominant image for the Swedish car builder.

Advanced Turbo V6 Engine:

With massive pulling power (350Nm) spread widely across the engine's speed range, Saab says that the 184kW (250hp) 2.8V6 Turbo generates more torque than any other 6-cylinder gasoline engine in the Saab 9-3 segment.

Saab Automobile Powertrain's expert knowledge and experience of turbocharging is recognised by its role as a center of expertise within General Motors for the development of turbocharged gasoline engines.

The Swedish engineers were therefore closely involved during the conceptual design and development of GM's new global V6 engine architecture, ensuring it included the possibility of a turbocharged application.

The 2.8V6 Turbo has a 60º vee-angle between its cylinder banks for perfect balance and combines excellent multi-valve refinement with outstanding performance. The all aluminium construction provides a light and compact architecture, well suited to its transverse, front-wheel-drive installation in the Saab 9-3 Aero.

The cylinder heads, each with double chain-driven overhead camshafts operating 4-valves per cylinder, are of high specification aluminium and unique to this turbocharged variant. The design ensures enhanced heat resistance under 85 bar cylinder pressures, as well as minimum maintenance costs.

Also unique are pistons with hard anodised ring grooves for durability and under-skirt oil jet cooling, together with steel con-rods that are strengthened by sinter-forging, a process that involves molding metal in a powered form. The exhaust valves are filled with sodium to further enhance cooling.

For improved engine breathing, variable cam phasing on the inlet side is electronically controlled and hydraulically actuated, allowing continuously variable adjustment through 50º of crankshaft rotation. On the road, this translates to a more flexible power delivery and better fuel economy under different engine loads.

A die-cast aluminium oil sump is designed to increase structural stiffness and the strong, four-bearing crankshaft is made from micro-alloy forged steel, a specification more commonly seen in competition performance or diesel engines.

The twin-scroll, water-cooled Mitsubishi TDO4-15TK turbocharger, operates at 0.6 bar (8.7 psi) maximum boost with intercooling and an integral by-pass valve. It is mounted centrally above the transmission and fed by both banks of cylinders. The use of two separate inlet tracts, one for each cylinder bank, separates the exhaust gas pulses, improving gas flow, reducing energy losses and raising turbocharger efficiency.

The turbine wheel is made from a special high-grade steel alloy, commonly used in the turbocharged engines of world championship rally cars, which is resistant to erosion, cracking and creeping under high temperatures and centrifugal forces.

Also unique are double-skin exhaust manifolds, which are hydroformed with stainless steel liners to improve cold start emissions by minimising heat absorption to the manifold.

For driving comfort, control of the electronic throttle through the movement of the accelerator pedal is programmed to be sensitive to different driving conditions, with greater pedal movement introduced at lower vehicle speeds, such as when manoeuvring or parking. At low engine speeds, the engine control system also brings the turbo in quickly by momentarily opening the throttle slightly more than requested by the driver.

On the road the new 9-3 Aero 2.8V6 Turbo packs a formidable punch, claims Saab, and the driver will also immediately appreciate the smooth power delivery, like an iron first in a velvet glove. Apart from the boost gauge in the dashboard, the only clue to the presence of a turbocharger is an uncannily effortless rate of acceleration.

Pick-up from tick-over at just 720rpm is instant, due to the engine's relatively large multi-cylinder capacity. At about 1,000rpm, the turbo begins to build a massive wall of torque that is already in place by the time the tachometer swings through 2000rpm. It endows the 9-3 Aero with a level of performance never before seen in a Saab car.

Maximum torque is generated all the way from 2000rpm to 4500rpm, with 90 per cent of this value available at an exceptionally low 1500rpm. Careful programming of the engine management software means that under a full throttle load, from take-off or low engine speeds, 90 per cent of maximum acceleration is delivered within one second.

The zero to 100km/h dash is accomplished in just 6.9 seconds, but in-gear acceleration provides even more impressive evidence of this engine's outstanding elasticity. In top gear, the transition from 80 to 120km/h can be accomplished in just 8.3 seconds, a figure that places the 9-3 Aero among the very best in its class.

The fun-to-drive nature of this performance is also matched by an exhilarating engine note that can be heard inside and outside the car. This has been achieved by tuning the twin sports exhausts downstream of the main catalyst. It gives the new Saab 9-3 Aero a distinctive aural character in keeping with its position as the sporting flagship of the range.

The engine is offered with a choice of 6-speed manual or automatic transmissions. The close-ratio manual gearbox includes dual output shafts to reduce transmission vibration, together with a dual mass flywheel - this ensures smooth and refined performance.

The 'smart' Asin AW automatic transmission is adaptive to driver usage patterns and prevailing road conditions. It can sense changes in engine performance, engine load, road gradient and altitude, quickly finding the right gear without an irritating 'hunting'.

For closer driver involvement, Saab Sentronic, a sequential manual gearshift, is also included. When the shift lever is moved across the gate to ‘manual’ Sentronic mode, ‘up’ and ‘down’ changes can be made with full lock-up in 3/4/5 or 6th gears. This process is taken a step further by the option of steering wheel buttons, which bring gear-shifting right to the fingertips of the driver.

Overall, the 2.8V6 Turbo generates class-leading levels of torque with a seamless, turbine-like power delivery. It combines the inherent advantages of a 6-cylinder engine - refinement and a rapid throttle response - with the effortless, torque-boosting properties of turbocharging.

Saab 2.8-litre V6 Turbo Specifications:

Technical Specifications and Performance
2,792 cc. V6. Bore 89mm, Stroke 74.8mm
Aluminium cylinder heads and block
2 x DOHC chain-driven, 24-valves
Variable valve timing (inlet only)
Turbocharged, intercooled
Max boost pressure: 0.6 bar (8.7 psi)
Compression ratio: 9.5:1
Bosch Motronic engine management
Direct ignition, multi-point fuel injection, electronic throttle control
Max.power: 184kW @ 5500rpm
Max.torque: 350Nm @ 2000 - 4500rpm