Saab 9-3: Powertrain

Saab’s Turbo Expertise Charges Forward

• All new, aluminum 2.0-liter turbo engine
• Excellent torque, driveability and refinement
• New Trionic 8 engine management system
• New automatic and manual transmissions

“The closer integration of the new engines and transmissions has given us a far more sophisticated and refined level of performance.”
– Kent Bovellan, Project Leader, new Saab 9-3

Exceptional turbocharged performance delivering new levels of mechanical refinement and driveability were the objectives of powertrain development for the new Saab 9-3.

Saab engineers have long been regarded as world leaders in the art of turbocharging, a distinction recognized by Saab’s appointment as the center of expertise within General Motors for turbocharged gasoline engine development. Now with the launch of the new 9-3, Saab has matched the renowned torque of its engines with a more progressive power delivery.

A new, all-aluminum 2.0-liter turbocharged engine, based on the L850 series, has been developed by engineers based at Saab’s engine plant in Södertälje, Sweden and is configured for U.S.-specification cars with two levels of power output: 175 or 210 hp. Transmissions include both an improved five-speed and a new six-speed manual gearbox, as well as a new five-speed automatic transmission with Saab Sentronic manual gear selection and the option of steering wheel controls on the Vector.

Advances in electronic engine and transmission control deliver appreciable improvements in throttle response, torque delivery and power-on/power-off behavior. The smooth, turbocharged performance of the new Saab 9-3 is the perfect complement to its superb chassis dynamics for a rewarding, fun-to-drive experience.

New lightweight 2.0-liter Turbo
The all-aluminum, four-cylinder 2.0-liter gasoline engine is 33 lbs. lighter than its predecessor. It is smoother, quieter, more compact and better packaged. It also operates with lower frictional losses for improved fuel consumption and lower exhaust emissions.

The block is perfectly “square” in configuration, with a bore and stroke of 3.38 in. (86 mm), and carries a unique Saab four-valve cylinder head, maintenance-free chain-driven camshafts, counter-rotating balancer shafts, a dual mass flywheel and an integrated oil cooler. It is controlled by the latest Trionic 8 version of Saab’s own, in-house engine management system, the most powerful in commercial production.

All main internal components are unique to the turbocharged application in the new Saab 9-3. These include a five-bearing forged steel crankshaft, strengthened connecting rods, redesigned pistons, piston oil cooling jets and reprofiled camshafts. The cylinder head is a unique alloy casting optimized for turbocharging, with substantially revised inlet porting, modified inlet valves and sodium-cooled exhaust valves.

A major innovation for Saab is the in-board location of the turbocharger, behind the transversely-installed engine. This position allows an even quicker warm-up for the front exhaust catalyst; giving improved fuel consumption and lower cold start emissions, as well as benefiting weight distribution.

A Garrett GT20 turbocharger is used for the 175-hp engine, with maximum boost pressure set at 0.7 bar or 10.15 psi. A larger Mitsubishi TDO4 unit, operating at 0.85 bar or 12.3 psi, provides boost for the 210-hp version, which also has more aggressive camshafts. Both turbos have integrated by-pass valves.

The power characteristics of both engines set new Saab standards for running refinement, throttle response and progressive torque delivery, as well as yielding even better fuel consumption and lower CO2 emissions.

In common with all Saab gasoline engines, outstanding levels of torque are generated at low engine speeds, with 90 percent of the peak value available from below 2,000 rpm. Maximum power and torque figures are as follows:

2.0t 175 hp @ 5,500 rpm 195 lb.-ft @ 2,500 rpm
2.0T 210 hp @ 5,300 rpm 221 lb.-ft @ 2,500 rpm


Improved driveability from new Trionic 8
Saab is alone among the world’s premium carmakers in producing its own engine management system. The Trionic system is specifically tailored to the characteristics of turbocharged engines, and allows Saab to carry out speedier, more effective development work. Ignition timing, fuel injection, turbo boost pressure, air mass measurement and the throttle setting are all key engine functions controlled by the Saab-written Trionic software, making it the most sophisticated engine management system in commercial production for turbocharged engines.

In the new Saab 9-3, Trionic 8 now incorporates engine start-up and temperature control and further developments for improving torque management and throttle response. It is this in¬house capability that provides the key to achieving one of the powertrain development team’s main objectives: better driveability.

The torque delivery of the engine is now more linear. Under acceleration, Trionic can sense, for example, if there is insufficient traction available for a given throttle setting and will modulate engine torque accordingly. The adjustments may be hardly noticeable, but effectively make the driving experience smoother and more enjoyable.

Uncomfortable jerks, which can be experienced when suddenly lifting off or stomping hard on the throttle, are also largely eliminated. Trionic is able to “read” and anticipate different driving situations, cushioning the transitory effects of large throttle movements by comparing parameters such as road speed, engine speed, engine loading and gear selected. The end result is a smooth, powerful and extremely pliable powertrain, free of driveline “lash” under sudden throttle movements.

The Trionic system enables Saab to constantly achieve improved operating efficiencies, and is a powerful electronic platform for Saab’s own future engine technologies.

As a measure of its sophistication, Trionic is unique in monitoring ionization rates at each spark plug to individually control and adjust the combustion process for each cylinder. This involves about two million calculations per second! To avoid such complexity, many competitors’ systems simply apply an average taken from all cylinders.

Unique engine installation
As part of the extensive program to minimize low frequency noise and vibration, Saab engineers have adopted a completely new “pendulum” technique for the engine mountings.

In order to absorb the primary torque forces, which are generated at the bottom of the engine, the entire powertrain assembly is, in effect, suspended from two top mounts, one hydraulically damped, in the engine bay. Two short, aluminium torque rods, with rubber bushings at both ends, are also fitted low down, between the back of the powertrain and the rear of the front sub-frame. One is attached to the oil sump and the other to the transmission. These act like mini shock absorbers, allowing lateral movement, in or out, of up to 20 mm, equivalent to a swing of 4.5° from the vertical, just like a pendulum.

This sophisticated installation directs forces to the bottom of the car’s structure and away from the passenger cabin, playing an important role in isolating the interior from unwanted engine noise and vibration.

New automatic transmission

A new “smart” five-speed automatic transmission is available, which includes Saab Sentronic, a sequential manual gear selection, and the option of additional steering wheel gear-change controls on the Vector model. The greater manual control offered by Saab Sentronic means that “sport” or “winter” mode settings are no longer required.

This transmission, produced by Asin AW, is adaptive to both the driver and road conditions and is programmed to fully exploit the Saab turbo’s power characteristics. It can sense changes in engine performance, engine load, road gradient or altitude and will quickly find the right gear without any irritating “hunting” between gears. It will also automatically engage neutral when braking to a stop.

For closer driver involvement, the shift lever can be moved across the gate to “manual” Sentronic mode, giving sequential “up” or “down” changes at will with full torque converter lock-up in all five speeds. This process is taken a step further by the option of steering wheel buttons, which bring gear-shifting control right to the driver’s fingertips.

Six-speed manual gearbox
Saab’s transmission plant in Gothenburg, Sweden, is a major supplier of manual gearboxes to General Motors. For the new 9-3, a completely new, six-speed manual gearbox has been designed.

The six-speed will be standard in the Arc and Vector models, and is capable of handling extremely high torque levels, up to 300 lb.-ft. It features improved syncromesh for better gear shifting quality and double output shafts for lightness and compact size. The additional sixth gear is extremely tall for economical, high speed cruising.

Improved manual gear shift
The gear shift quality of the current five-speed transmission is substantially upgraded for the new Saab 9-3 by the adoption of a cable linkage, instead of rods, from the gear lever.

The driver now enjoys a faster gear shift with a much smoother and more positive feel. In combination with the dual mass flywheel, noise resonance and vibration are also reduced. It is another small part of the powertrain team’s mission for improved on-the-road refinement.

New Saab 9-3 In Focus: How Saab “turned the corner”
Saab engineers love to “talk torque,” because it is an engine’s pulling power that defines its true performance. The ability to deliver strong, low-down power has always been an outstanding feature of Saab turbo engines.

It is graphically summed up by that classic “Ayers Rock” torque plateau, depicting the impressive power delivery of Trionic-controlled Saab turbos. Now, instead of Ayers Rock, the torque curve is more like the Houston Astrodome!

Saab experts have succeeded in “turning the corner,” getting rid of that sudden, sheer cliff face. The smoother contour of the dome-shaped curve translates to an engine that’s more progressive, delivering more torque earlier and slightly less later, during pick-up from idle (at just 670 rpm) to 2,000 rpm. Once in the mid-range, towards the crown of “the dome,” it’s business as usual, with no shortage of power!

Trionic 8 brings the turbo in slightly earlier and a clever, electronic sleight of hand is used at low engine revs, very briefly opening the throttle slightly more than requested in order to spool up the turbo quicker. It’s all possible thanks to the drive-by-wire, electronic throttle and the power of the Trionic “brain.”

“The driver communicates with the engine through the accelerator pedal,” says Birger Schlaich, Manager, Powertrain Integration, “and we want to make that experience as precise and pleasant as possible.

“Another good feature for better driveability is the programming of the signal from accelerator pedal itself. At low speeds, there is much more movement for a given amount of power in order to make the car nicer to control, such as when parking and reversing. At higher speeds, less movement is required, and that’s better for a quick response when overtaking, for example,” he added.

“For the new 9-3 we have done a lot of fine tuning such as this to make the behavior of the powertrain as seamless as possible. We are quite pleased with the results.”