One aim of the new Alfa 159 Project was to set the benchmark for passive safety. To do this, the Alfa Romeo engineers designed and developed the new "premium" floorpan, with high performance materials, multiply sheet metal and laser welding. The architecture of the bodyshell also benefits from numerous measures such as the use of boxed elements that are connected rigidly both transversely and vertically, three load lines in the front, longitudinals that run the whole length of the car, built-in structures and a larger number of spot welds around structural nodes. The result is the excellent torsional rigidity of the bodyshell, the best in its segment at over 180,000 daNm/rad
2)Front suspension and steering
The new high wishbone layout adopted on the front suspension is the ideal solution to guarantee precise control of wheel movement, with a clearly defined steering axis. The architecture was borrowed from racing and endows the car with outstanding dynamic performance, and extremely sensitive, pinpoint steering. The high double wishbone was already used on the 156 and has been further improved on the new Alfa 159.
First of all, the steering axis was brought closer to the centre of the wheel, increasing the Ackerman level (to increase parallel wheel movement when steering) for better response when cornering, thanks to the steering which is the most direct in its category. The steering of the new Alfa 159 has an excellent ratio (12.7° steer for every degree of wheel steer) which translates into a more direct response for the driver, more responsive steering and better stability control. What is more, painstaking analysis of the matching of the steering geometry and the wheelarch volume, made it possible to achieve high steering angles even with the largest tyres, and this significantly improved the turning circle between kerbs (11.1 metres).
Great attention was paid to the new wheel upright where it connects to the levers, exploiting the available space inside the rims in full, and this has significant advantages in terms of lateral rigidity; the size of the coaxial damper spring unit has been increased to improve its capacity to absorb road roughness; the aluminium lower wishbone combines excellent structural characteristics and a much lower weight; the upper aluminium arm fits a pair of dry friction sliding bushes, a solution chosen because it is stronger and more reliable, and guarantees a more progressive action. And finally, the suspension is connected to the chassis by a closed geometry frame which is stiffer than the previous solution which had a simple crossbeam.
3)The rear suspension of the Alfa 159 now features:
• A higher anchorage point of the longitudinal link, which is now positioned higher than the centre of the wheel, allowing the suspension to perform a longer, more flexible stroke, with an optimal response when negotiating an obstacle.
• The aluminium upright, fitted with a third generation, extremely rigid hub, supports the connection bushes for the camber lever and the longitudinal link.
• The bi-tube spring-damper unit is larger than other conventional solutions, this achieves a better compromise between handling and comfort.
• The camber link, which allows the static camber to be adjusted and produces a geometry capable of guaranteeing a good camber recovery with wheel shake to ensure that the wheel rests perfectly on the road and wear is thus uniform, even when the car is pushed to the limit.
• The rear hydraulic bush guarantees excellent filtering of roughness, and allows the wheel to retract slightly when negotiating an obstacle.
• A high yield steel crossbeam isolated from the bodyshell by four elastic bushes that dampen high frequency vibration.
4)The Alfa Romeo Q4 four-wheel drive system
The new Alfa 159 proposes an evolution of the permanent 4x4 system with three differentials (with a Torsen C self-locking unit at the centre) already adopted on the Crosswagon Q4. The heart of this project is the "Alfa Romeo Q4 four-wheel drive" system which splits torque constantly and dynamically between the four wheels, reaching the highest levels of active safety and sportiness. The Torsen C self-locking differential sends drive torque 57% to the rear wheels and 43% to the front. The system also guarantees excellent traction in all grip conditions by automatically checking slip.
The torque split between the front and rear axles is modulated constantly by the Torsen C central differential on the basis of grip. This feature harnesses sportiness to enhance active safety. Modulation is mechanical, continuous and gradual, to enhance the perception of optimal, enjoyable, easy driving. There are no gaps in the torque delivery. Where grip is concerned, the behaviour adapts gradually and smoothly to changing road conditions. This "mechanical" control is backed up by electronic stability control, which boosts performance and safety margins, in line with the Alfa Romeo philosophy.
The four-wheel drive car is the state of the art in technical terms and offers important advantages.
• Q4 permanent four-wheel drive with a Torsen C self-locking differential makes for better roadholding, entertainment and smooth responses. Other technological archetypes with electronically controlled joints do not achieve the optimal balance between understeer and oversteer or the smoothness that are innate in the Alfa 159, and translate into superb active safety.
• The torque split in favour of the rear axle makes driving even more entertaining, because it makes the car even easier to handle, without detracting in any way from stability during sudden lane changes on the motorway, or other emergency manoeuvres.
• The ability to travel safely in poor grip conditions without the aid of electronics in torque split for constant driving pleasure.
We could say that the Alfa 159 Q4 interprets four-wheel drive from the Alfa Romeo point of view: it is basically a "mechanical" system enhanced by cutting edge electronic technology to guarantee maximum comfort and entertainment, combined with superb performance and absolute safety.
5)Main technical features
The new 6-cylinder engine of the Alfa 159 continues the strategy begun with the 4-cylinder engines, and adopts the JTS (Jet Thrust Stoichiometric) direct injection system. This is an original Alfa Romeo concept that injects the fuel directly into the combustion chamber with a stoichiometric mixture optimised to enhance performance, but also guarantees low consumption and respect for the Euro4 emissions limits.
Numerous important components have been designed from scratch and are exclusive to the Alfa Romeo V6 engine. To start with, the cylinder head is aluminium and has 4 valves per cylinder, 2 camshafts per bank with the "Twin Phaser" continuous variable valve timing (intake and exhaust) already adopted on Alfa Romeo 4-cylinder engines and now applied on a 6-cylinder engine for the first time. Variable valve timing allows the phase angle on both cams to be varied by 50°, maximising performance on one hand, because the best phase can be chosen at all engine speeds, and reducing consumption and emissions with partial loads on the other.
At the same time it is possible to optimise the volumetric efficiency of the engine over the whole operating range, exploiting the degrees of freedom offered by variable valve timing: this means a very favourable torque curve, with 90% of peak torque available from 1800 rpm (290 Nm) and maintained over a broad range (from 1800 rpm to 6250 rpm). The valves are controlled by a roller finger system, with low mechanical dissipation, and hydraulic uptake of tappet play.
Another peculiar feature is the camshaft drive system which uses a primary chain that transmits the drive to the heads via two secondary chains. Tension is provided by automatic hydraulic tensioners which need no maintenance at all during the life of the engine.
The 185 bhp 2.2 JTS and the 160 bhp 1.9 JTS
The 4-cylinder engines of the Alfa 159 are extremely light because they have aluminium cylinder heads and crankcases (they are approximately 20% lighter than the engines they replace
Another peculiar feature of the 2.2 and 1.9 JTS engines that equip the Alfa 159 is the camshaft drive system which uses a chain; unlike a conventional belt drive, this system has the advantage of not needing to be replaced during the lifespan of the engine.
And to guarantee the performance one expects of an Alfa Romeo, the timing diaphragm has also been reviewed, adopting larger profiles which made it possible to achieve a maximum power output of 6500 rpm (the system is fine tuned to operate at over 7,000 rpm, the maximum rev speed allowed by the electronic speed limiter).
That is not all. To achieve the best volumetric efficiency, the maximum lift reaches 10.3 mm, while to enhance vibrational and acoustic comfort, the engine is equipped with two counter-rotating balancer shafts which virtually eliminate the second degree alternate forces that are typical of straight-4 engines. The generous power delivery of the engine (80 bhp/l on the 2.2 JTS) made it necessary to adopt sodium-cooled exhaust valves.