Saab 9-4x: Powertrain

Note: this press release is designated as being for Europe and rest of world, not for US. I’m not sure what the differences will be.

——

Compact V6 Engines Deliver High Efficiency

  • Entry model with 265 hp, naturally-aspirated 3.0V6
  • Top-of-the-line Aero features 300 hp 2.8V6 turbo
  • Adaptive, six-speed automatic transmissions

The Saab 9-4X is powered by a choice of two compact, six-cylinder engines, each featuring advanced technologies that deliver power ratings typical of larger displacement engines, but with better fuel economy and lower emissions.

A 265 hp, 3.0-liter V6 motor is fitted to the entry model and a turbocharged, 2.8-liter V6 with 300 hp – as used in the new 9-5 sedan – is fitted to Aero models. Both units are transversely-mounted and mated to six-speed automatic transmissions with Saab XWD. .

The engines feature electronic management, electronic throttle control, direct ignition and four valves per cylinder operated by overhead, maintenance-free, chain-driven camshafts. Variable valve timing, on both inlet and exhaust sides, allows the opening and closing of the valves to be adjusted according to engine speed and load. This enables a broader spread of torque, higher maximum power and improved fuel consumption, as well as better emissions control.

To give minimal piston friction and wear characteristics, while also benefiting fuel and oil consumption, the cylinder walls of the engines are laser-etched for an ultra smooth finish. Under-skirt piston oil cooling and sodium-filled exhaust valves are further efficiency measures.

A torque-based engine management strategy is used for both engines. This calculates an optimal throttle position, cam phasing, ignition timing and turbo charge pressure for all engine loads and speeds.

3.0V6, naturally-aspirated
This fuel-efficient, all-aluminum engine delivers 265 hp (195 kW) at 6,950 rpm and plentiful torque of 302 Nm at 5,200 rpm. It propels the 9-4X from zero to 100 km/h in just 9.0 seconds.

The engine features direct injection, which delivers fuel under high pressure directly into the combustion chamber, instead of the inlet port, where it is mixed with air. This improves the efficiency of the combustion process and enables a high 11.7 compression ratio, increasing power and improving fuel economy on part or full throttle. During cold starting, when engine exhaust emissions are at their highest, direction injection also offers an improvement of up to 25%.

Apart from an aluminum construction, other weight-saving and/or noise reduction features include: a composite, instead of aluminum, upper intake manifold; an integral exhaust manifold, eliminating a separate unit; and composite, instead of cast aluminum, camshaft covers.

The six-speed automatic transmission applies a wide selection of shift patterns that adapt to the style and habits of the driver, anticipating when maximum acceleration or maximum efficiency is required. It also adapts to the prevailing road conditions, reducing gear shifting when climbing or descending and using engine braking assistance during down changes. It features a clutch-to-clutch shift operation, with manual sequential gear selection available via the shifter.

2.8V6 Turbo.
Available exclusively in Aero specification, this all-aluminum engine has a classic 60° angle between the cylinder banks to give optimum balance for vibration-free running. It generates 300 hp (221 kW) at 5,500 rpm and an impressive 400 Nm spread of torque between 2,000 and 5,000 rpm.

On the road, it delivers giving zero to 100 hm/h acceleration in 8.3 seconds. Like all turbo engines, it offers performance typical of larger engine, while delivering better fuel economy when boost is not required, under highway cruising, for example.

The single, twin-scroll turbocharger is mounted centrally above the transmission and fed by both banks of cylinders. The use of two inlet tracts, one for each cylinder bank, separates the exhaust gas pulses, improving gas flow, reducing energy losses and raising turbocharger efficiency. The turbo is water-cooled and uses air-to-air intercooling to increase intake charge density.

A strong, forged-steel crankshaft runs in four main bearings and the steel connecting rods are sinter forged for extra strength and durability. The polymer-coated, aluminum pistons and the floating wrist-pins are cooled and further lubricated by triple under-skirt oil jets.

The exhaust manifolds are double-skinned with hydroformed stainless steel liners to improve cold start emissions by minimizing heat absorption to the manifold. Air injection into each exhaust manifold for up to 30 seconds after a cold start also helps the central pre-catalyst, positioned upstream of the main catalytic converter, achieve ‘light off’, its effective working temperature, as early as possible.

For smooth and quiet running, the cast aluminum oil pan is stiffened and bolted to the transmission bell housing, as well as the engine block, eliminating points of vibration. The camshaft covers are fully isolated and made from composite material to provide an effective noise barrier.

The six-speed automatic transmission for this engine includes an integrated electronic control module, which eliminates the need for any external wiring. It features an adaptive shifting logic similar to that of the 3.0V6i transmission, while adding manual gear selection via steering wheel controls to complement the manual gear selection with the shifter.

Fuel consumption figures for both engines have yet to be finalised.

wpDiscuz