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The Alfa 159 is equipped with three petrol and three turbodiesel engines, all combined with new mechanical six-speed gearboxes, with short strokes, precise engagement and low loads. After the launch, automatic transmissions and a Selespeed robotised gearbox will also be available on some versions, all with six speeds. The 3.2 JTS (260 bhp), 2.2 JTS (185 bhp) and 1.9 JTS (160 bhp) were developed to respect the brief from the Alfa Romeo engineers and represent the brand's interpretation of the direct injection petrol engine, which translates into enjoyable driving and high performance for the customer. The three engines adopt the direct injection JTS (Jet Thrust Stoichiometric) combustion system, which produces brilliant engine performance. The 3 engines deliver the quality one expects from Alfa Romeo, having been fine tuned on the Balocco test track, while final assembly takes place in the Alfa plant in Pomigliano. All the JTS engines obviously meet Euro 4 limits.

The Alfa 159 is also available with three Multijet turbodiesel engines, the 1.9 8v JTDM (120 bhp), 1.9 16v JTDM (150 bhp) and the new 2.4 20v JTDM (200 bhp) which guarantee excellent power and torque deliveries in all driving conditions, combined with low fuel consumption. They are all combined with 6-speed gearboxes (including the automatic transmission that will be available on the 150 bhp 1.9 JTDM after the launch), true jewels of automotive engineering that confirm Fiat Auto's supremacy in this field. When it developed the Multijet system, the Fiat Group set its stamp on the diesel engine market. The three Multijet engines of the Alfa 159 obviously respect Euro 4 limits, and incorporate a DPF (particulate trap) that eliminates fine dust in line with the limits currently envisaged for future Euro 5 legislation. It is a "for life" system that does not need to be regenerated with additives, and will be eligible for tax incentives.

The new 260 bhp 3.2 JTS V6 engine

The Alfa Romeo "cuore sportivo" really beats in the new V6 3.2 litre petrol engine, which delivers 260 bhp. It represents a significant departure from Alfa's previous V6 engine, as well as its natural evolution. The new JTS engine is capable of a power delivery of 260 bhp (20 bhp or 8% more than the previous 3.2 V6); peak torque of 322 Nm at 4,500 rpm (+ 33 Nm, an increase of more than 11%); a specific power of 60 kW/l and specific torque of 100 Nm/l; a significant increase in torque at low speeds to improve the smooth delivery (approximately 30 Nm more than the previous 3.2 V6 engine, starting from 1500 rpm); maximum revs of 7,200 rpm; minimal maintenance (hydraulic tappets and timing gear with chain drive); low weight (aluminium cylinder head and crankcase); and Euro4 exhaust emissions limits. With this equipment, the Alfa 159 can reach a top speed of 240 km/h and accelerate from 0 to 100 km/h in 7 seconds.

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 high pressure fuel pump of the direct injection system is mounted on the cylinder head, driven by a camshaft, maintaining the pressure of the injected fuel at 120 bar by a built-in pressure regulator.

The inlet ports and combustion chamber assembly is designed to optimise the air-fuel mixture, to achieve the correct turbulence of the inlet air, forming a homogeneous mixture, for stable, complete combustion that produces fewer pollutants. The four valves per cylinder with diameters of 33.4 mm on the inlet and 28.4 mm on the exhaust guarantee suitable permeability to enhance engine performance. The volumes and port geometry of the aluminium inlet casing have also been adapted to the high air delivery of the high revs to enhance performance. The electronic throttle assembly with a 72 mm throttle valve is mounted on this casing. And finally, the compression ratio of 11.25:1 guarantees excellent engine performance even with regular 95 octane fuel.

Briefly, the main technical features that distinguish the new 3.2 V6 engine from the previous V6 engine are:

  • twin overhead camshaft with low friction drive;

  • direct petrol injection;

  • double continuous variable valve timing on the inlet and exhaust;

  • cylinder head in light aluminium alloy;

  • hydraulic tappets with automatic play uptake;

  • crankcase in light aluminium alloy;

  • maintenance-free timing gear drive chain;

  • Poly V automatic tensioner belt to drive the engine accessories;

  • throttle valve with electronic drive-by-wire activation;

  • single ignition coils;

  • low specific consumption and emissions;

  • EOBD;

  • 4 lambda probes to control emissions;

  • double knock sensor to improve knock sensitivity and to optimise peak performance;

  • high performance exhaust manifold with built-in pre-catalysts;

  • minimum maintenance;

  • Euro 4 emissions.

The 3.2 V6 engine features an exhaust system that envisages a first group of catalysing elements relatively close to the cylinder heads to reduce the emissions level at the start of operation. Two catalysts under the floorpan and four lambda probes complete the system, so that the engine respects Euro 4 limits without adopting special systems such as secondary air or electric heating.

Another feature of the 3.2 V6 engine is the direct injection system (the fuel is supplied directly to the combustion chamber) whose main advantage is that it improves evaporation and this increases the engine's volumetric efficiency. As a result, the supply of air and petrol is both denser and colder, which allows the compression ratio to be increased to 11.25, even if Euro Super petrol is used, with an octane index of 95 RON; a high compression ratio is useful because it makes it possible to increase both the performance and the energy efficiency of the engine. And ignition is provided by a single sparkplug per cylinder. Direct injection combined with 4-valve-per-cylinder geometry creates a mix that tends to be more concentrated at the centre of the combustion chamber. The ignition system fits a single ignition coil per cylinder.

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).

Alfa Romeo 159
Alfa Romeo 159
Alfa Romeo 159
Alfa Romeo 159
Alfa Romeo 159
Alfa Romeo 159

The timing gear control is particularly evolved, featuring a system of rocker arms and rollers, which significantly reduces dispersion due to friction in the cylinder head, and the "Twin Phaser" continuous variable valve timing system on the intake and exhaust valves, which optimises power output, torque and consumption.

The 2.2 JTS delivers 136 kW (185 bhp) and peak torque of 230 Nm (23.4 kgm) at 4,500 rpm, taking the car to a top speed of 222 km/h and accelerating from 0 to 100 km/h in 8.8 seconds. Torque is also excellent on the 1.9 JTS (190 Nm - 19.4 kgm at 4,500 rpm) 88% of which is already available at 2,000 rpm. And with a power delivery of 118 kW (160 bhp), the brilliant 1.9 JTS has a top speed of 212 km/h.

Main technical features

To start with, the Twin Phaser system adopts new cam lobes which allow the phase angle to be varied by 50 on both axes; this makes it possible to improve performance on one hand because the best phase can be chosen at all engine speeds, and to reduce consumption and emissions with partial loads, by the so-called Miller cycle. This combustion system, which is based on the postponed opening and closing of the inlet and exhaust valves - extends the expansive phase (converting more heat into energy), guarantees internal EGR (by preventing the release of the last exhaust gases, full of unburned particles) and postpones the closure of the inlet valve (reducing pumping losses).

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.

The combustion chamber is shaped like a roof with four valves per cylinder: with a bore of 86 mm, the large inlet valves measure 35.3 mm and the exhaust valves 30.3 mm, guaranteeing excellent permeability to enhance engine performance. And, in spite of the stroke of 94.6 mm, in order to limit the overall height of the engine, the engineers have modified the piston height, achieving a compression value of just 28 mm, which is excellent in view of the high power delivery.  Where the exhaust, injection and ignition systems are concerned, the two 4-cylinder JTS engines both adopt the strategies and features illustrated for the new 3.2 V6 engine.

The 200 bhp 2.4 JTDM 20v

Derived from the familiar 2.4 JTD 20 valve "Common Rail" engine, the new engine has 5 cylinders in line and is the most powerful engine in the JTD multivalve Multijet family, with a specific power of 84 bhp/litre.

The new engine offers numerous advantages. First of all, it is appreciably quieter during the heating stage, depending on the rev speed and ambient temperature. It is also extremely powerful (147 kW - 200 bhp at 4000 rpm), with a generous torque (400 Nm - 40.8 kgm at 2000 rpm).

There are four valves per cylinder, activated via hydraulic tappets and rocker arms by the twin overhead cam shaft. Several changes were made to the new turbodiesel engine to boost performance and engine torque at low speeds, and to eliminate noise and vibration. For example, the "Common Rail" system adopted on the 2.4 JTD Multijet 20v employs two new automatic control strategies for the setting and balance of the injected diesel fuel, to reduce noise and vibration.

The engine includes a number of new components, such as the cylinder head with small stem inlet valves to increase the quantity of inlet air, con rods of fractured steel and a new shape that increases mechanical resistance to the strong stress created by the increased power, an inlet manifold fitted with a throttle valve on one of the two inlet ports of the cylinders to control the turbulence of the air entering; a throttle valve to prevent shaking if the engine stalls, and an intercooler that is highly efficient thanks to its shape and position in the car, to guarantee the optimal temperature and density of the inlet air.

The electronic EGR exhaust gas cooling system has also been modified; the lubricating circuit has a new oil pump and an external air/oil heat exchanger to cool the oil, while the water pump on the cooling circuit is also new. In other words, a long list of improvements and changes that have produced a reliable, powerful engine which is sparing on fuel. Excellent results, achieved thanks to different engine control settings, an increase in the direct injection pressure to 1600 bar, and new turboblower settings. The turboboost is provided by a turboblower with a variable geometry turbo that helps to improve the power delivery, but also generates very high torque even at low engine speeds. In fact, 90% of peak torque is available between 1750 and 3500 rpm. These figures translate into extremely enjoyable driving and brilliant performance: the Alfa 159 has a top speed of 228 km/h and accelerates from 0 to 100 km/h in 8.4 seconds. Fuel consumption remains low (6.8 l/100 km in the mixed cycle).

A new 6-speed sequential automatic transmission will also be available with the new 200 bhp 2.4 JTD Multijet 20v engine in 2006, a compact light device that incorporates the control unit in the gearbox, and was designed paying particular attention to consumption. On one hand, the use of low friction oil boosts efficiency, while on the other, the sixth speed has been designed particularly for use on the motorway.

The 150 bhp and 120 bhp 1.9 JTDM

Both have 4 cylinders in line. The first is a 16 valve unit that delivers 150 bhp (110 kW) at 4,000 rpm and peak torque of 320 Nm (32.6 kgm) at 2,000 rpm; the second has 8 valves and delivers 120 bhp (88 kW) at 4,000 rpm and peak torque of 280 Nm (28.6 kgm) at 2,000 rpm. Changes were made to both engines to boost performance and engine torque at low speeds, and to reduce noise and vibration. For example, the Common Rail system includes two new strategies for automatically calibrating and balancing the diesel fuel injected, so as to lower noise and reduce vibration.

That is not all. The special features of the Alfa Romeo engine include a variable geometry turboblower with a special rotor that increases torque at low speeds (for the 1.9 JTDM 16v), and an inlet manifold with a throttle valve on one of the two inlet ports of the cylinders to control inlet air turbulence (for the 1.9 JTDM 16v engine).

Equipped with the 150 bhp 1.9 JTDM engine, the Alfa 159 reaches a top speed of 210 km/h, and accelerates from 0 to 100 km/h in 9.4 seconds (the values for the 120 bhp 1.9 JTDM are 191 km/h and 11 seconds respectively). In spite of this brilliant performance, fuel consumption is limited: 6 l/100 km on the mixed cycle (5.9 l/100 km for the 120 bhp 1.9 JTDM).

Text & Photos: Alfa Romeo