Saab 9-3X – On the move
The Saab 9-3X is designed to deliver levels of performance and a ‘fun-to-drive’ experience that fulfils the promise of its sporty looks. The advanced powertrain features an all-new, lightweight 2.8-liter V6 turbo engine, designed to incorporate Saab Combustion Control, a semi-automatic transmission and a state-of-the-art, ‘intelligent’ four-wheel-drive system.
The ‘Ecopower 2’ all-aluminum-alloy, 2.8-liter V6 engine is benchmarked to set new standards in efficiency, refinement, packaging and emissions control. Saab Automobile is GM’s global center of excellence for charged engines, and Saab engineers have been directly involved throughout the engine’s design and development program.
The slim, 60-degree configuration features double overhead camshafts, four valves per cylinder, direct ignition and variable valve timing. Maximum power is 280 bhp at 5,500 rpm but, in Saab tradition, torque is of more importance and is with this engine extremely generous, with almost 400 Nm available throughout the operating range from as low as 1,700 rpm.
The engine is very light and, in view of its compact dimensions, is ideally suited to a transverse installation. The single turbocharger is mounted on the transmission alongside the engine, feeding through the central intake manifolds. Main features include:
This revolutionary technology from Saab improves fuel consumption by up to 10 per cent and cuts emissions by as much as 75 per cent, all without impairing engine performance. Direct injection, variable valve timing and a variable spark gap are the key features, allied to a spark plug injector which provides air-assisted fuel injection and turbulence for better combustion, as well as a high-energy spark.
SCC allows exhaust gases to comprise up to 70 per cent of the combustion mixture, a far higher proportion than conventional exhaust-gas-recirculation systems. Carbon monoxide and hyrdocarbon emissions are reduced by almost 50 per cent and nitrogen oxides by 75 per cent. The Saab Ecopower 2 V6 is the first production engine designed to incorporate this technology.
The turbine wheel is made from a titanium/aluminum alloy for lightness, durability and low inertia. ‘Twin scroll’ management of the exhaust-gas flow to the compressor speeds up airflow at low engine speeds to give an improved throttle response and engine pick up.
Oil quality sensor.
This feature allows for extended change intervals, depending on how the engine is driven. If it is used relatively lightly, the driver can expect to cover up to double the usual 30,000 km between changes.
Double-skinned exhaust manifolds.
Both are made from hydroformed stainless steel for improved heat management and quicker ‘light off’ for the catalytic converters during engine warm-up.
New Saab Transmission
The Saab 9-3X is equipped with Saab’s newly developed semi-automatic transmission. This allows the driver to enjoy both the benefits of an adaptive, five-speed automatic transmission and the close control of manual gear shifting.
The automatic transmission adapts its gear-shifting pattern to match the style of driving or prevailing road conditions. It can sense changes in road gradient to avoid ‘hunting’ between gears and will engage neutral during an emergency stop.
At any time, the driver can override the automatic ‘drive’ program and enjoy fingertip control by manually changing gear via buttons on the 9-3X’s steering wheel.
Advanced Chassis and Four-Wheel-Drive System
To achieve its ‘fun to drive’ goal, the Saab 9-3X utilizes sophisticated chassis, suspension and drivetrain technology. The car’s performance, handling and ride quality in everyday use should not be compromised by its off-road capabilities.
Chassis and suspension.
The four-link rear suspension has been adapted for four-wheel drive and incorporates a passive steer feature when cornering, allowing the rear wheels to more closely follow the path of the front wheels. This improves steering feel and helps to limit both oversteer and understeer characteristics. A bottom toe link also improves stability under heavy braking at high speed.
An Electronic Stability Program (ESP) further improves maneuverability, the Saab system being particularly ‘driver friendly’ by avoiding harsh interventions. In addition to wheel-speed sensors in the ABS system, the ESP also includes sensors to measure steering angle, yaw rate and lateral acceleration. Each wheel can be braked independently, allowing excessive oversteer or understeer to be controlled so smoothly that the driver may often be unaware of any intervention.
As a further refinement of the Saab 9-3X’s agility, Saab engineers are also developing an adaptive damper program for optimized body control according to off-road or on-road conditions.
‘Intelligent’ Four-Wheel Drive.
The integrated Saab system is ‘intelligent’, using inputs from the ESP and ABS wheel sensors as well as the electronic throttle control to distribute power in the most efficient way. The system is being developed to ensure predictable and consistent handling in all road conditions, in addition to maximizing off-road traction.
Drive is taken from the front transmission via a propshaft to an electronically controlled, hydraulically operated, multi-plate clutch, which is located immediately ahead of a differential housing and driveshafts within the rear suspension unit. Messages from the various sensors are constantly interpreted in order to distribute power most effectively. In this way, the front/rear torque split is infinitely variable.
Saab engineers are currently fine-tuning the system to establish a ‘baseline’ torque split and to ensure that the clutch mechanism executes power shifts between the axles smoothly and progressively, without any sudden surprises for the driver.
Continue reading: Saab 9-3x – Part III