FACTfile - Alfa 159 - Page 4

Engines and Transmission

The Alfa 159 offers a choice of four powerplants. Two new direct injection petrol engines – 2.2 litre 136 kW 4-cylinder units and a 3.2 litre 191 kW V6 – combine the JTS (Jet Thrust Stoichiometric) direct injection technology of Alfa Romeo with continuously variable valve timing, (both inlet and exhaust), for the first time.

With specific power outputs of between 60 and 62 kW/litre, and almost 90% of maximum torque available at just 2000 rpm, all three new JTS units boast outstanding performance, yet offer significant fuel savings and readily comply with stringent Euro 4 exhaust emission regulations.

The two diesel engine options which complete the launch range exemplify the company’s on-going pre-eminence in the field of diesel technology: a 1.9 litre 16 valve 110 kW 4-cylinder unit, and a 2.4 litre 20 valve 147 kW 5-cylinder powerplant, both of which feature the company’s renowned JTD MultiJet common rail direct injection systems.

Both units also feature variable geometry turbocharging, and incorporate a ‘for life’, maintenance-free particulate trap (DPF) in anticipation of Euro 5 emissions regulations. Available in 2007, Alfa Romeo’s widely acclaimed twin overhead camshaft 1.9 JTDM 16v unit now combines a power delivery of 110 kW with a remarkable 305 Nm of torque – a figure comparable to that generated by the company’s four overhead camshaft, 24 valve, all-aluminium 3.2 litre JTS V6.

All four engines are mated to smooth, precise 6-speed manual gearboxes. Six-speed automatic transmissions will become available on 1.9 and 2.4 JTDM and 3.2 V6 JTS versions of the new Alfa 159 later in early 2007.

The 2.2 JTS and 1.9 JTDM versions of the new Alfa 159 are mated to the M32.6 6-speed manual gearbox, whilst 3.2 JTS and 2.4 JTDM models are equipped with the F40 6-speed manual transmission. The ratios of both transmissions have been chosen to emphasise performance, and gear change smoothness and accuracy have been enhanced by the use of multiple cone synchronisers.

Petrol Engines

3.2 JTS V6

1. 3195cc
2. 60 degree V, 6-cylinders, 24 valves
3. Power: 191 kW @ 6200rpm
4. Torque: 322 Nm @ 4500rpm
5. Timing gear: 4 OHC, continuous dual VVT
6. Transmission: 6-speed manual, 4-wheel drive
7. Top speed: 240 kmh
8. Acceleration 0-100 kmh: 7.0 seconds
9. Fuel consumption:
10. in town: 16.9 l/100 km
11. out of town: 8.4 l/100 km
12. combined: 11.5 l/100 km
13. CO2: 273 g/km

Making its debut in the new Alfa 159, the spirited new quadruple overhead camshaft all-aluminium V6 powerplant features both the company’s JTS direct petrol injection system and twin phase continuously variable valve timing. Developed by Fiat Powertrain Technologies, a new industrial enterprise created to integrate all the Fiat Group’s innovation capabilities and expertise in engines and transmissions, the new all-alloy engines feature cylinder heads, pistons, induction and exhaust systems designed and built by Alfa Romeo. Final assembly of this engine is carried out in Italy, at the Pomigliano D’Arco Alfa Romeo plant.

This outstanding unit takes its name – Jet Thrust Stoichiometric – from its specific combustion system, an original Alfa Romeo concept that involves the high pressure injection of fuel, at 120 bar, directly into the combustion chamber with a stoichiometric mixture optimised to increase engine power and torque first and foremost – thus adapting this technology to the requirements of a sporting car – whilst adopting the stratified charge method to reduce fuel consumption in a limited speed band close to idling.

Hence the 3.2 JTS engine in the new Alfa 159 operates with a lean burn system up to about 1500rpm, making significant fuel savings. Above this engine speed, however, it burns a stoichiometric air-fuel mixture – i.e. with a conventional 14.7:1 ratio between the two components – thus guaranteeing performance superior to that achievable by a conventional, indirect injection unit.

Primarily, this is because fuel injected directly into the combustion chamber – instead of the intake ports – cools intake air, thus increasing the engine’s volumetric efficiency. As the temperature drops, so the gases increase in density and the volume therefore decreases, allowing more air into the combustion chamber. Cooling the chamber also reduces the risk of engine knock, allowing for an increase in compression ratio – in this case to 11.25:1 – and a commensurate improvement in engine efficiency.

Allied to JTS technology, the light aluminium alloy cylinder heads of the new 3.2 litre V6 also features ‘Twin Phaser’ continuously variable valve timing – for both intake and exhaust – already adopted on 4-cylinder JTS Alfa Romeo engines. Via two camshafts per cylinder bank, variable valve timing allows the phase angle of both inlet and exhaust cams to be varied by up to 50 degrees, optimising the volumetric efficiency of the engine at all engine speeds whilst reducing fuel consumption and emissions under lighter throttle settings.

The new camshaft drive system features maintenance-free chain drive with automatic hydraulic tensioners, whilst the valves themselves are controlled by a low friction roller finger system with hydraulic uptake of tappet play.

This refined new V6 combines power and torque peaks of 191 kW at 6200rpm and 322 Nm at 4500rpm respectively with smooth, linear power delivery from low speeds. Some 90% of peak torque is available from just 1800rpm and maintained up to 6250rpm. Hence, the 3.2 litre V6 24v unit delivers sensational performance, but is also very docile, and the Alfa 159 can cruise effortlessly in sixth gear at less than 2000rpm, yet accelerate rapidly and smoothly away without the need for changing gear.

Mated to an F40 6-speed manual transmission and the Q4 four-wheel drive system, the 3.2 litre JTS V6 engine will accelerate the new Alfa 159 from 0-100 kmh in 7.0 seconds and on to a top speed of 240 kmh, yet it easily meets the stringent Euro Stage 4 exhaust emission limits.

2.2 JTS

1. 2198cc
2. 4-cylinders, 16 valves
3. Power: 136 kW @ 6500rpm
4. Torque: 230 Nm @ 4500rpm
5. Timing gear: DOHC, continuous dual VVT
6. Transmission: 6-speed manual
7. Top speed: 222 kmh
8. Acceleration 0-100 kmh: 8.8 seconds
9. Fuel consumption:
10. in town: 13.0 l/100 km
11. out of town: 7.3 l/100 km
12. combined: 9.4 l/100 km
13. CO2: 221 g/km

The new 2.2 version of the 4-cylinder Alfa Romeo JTS powerplant features aluminium cylinder heads, blocks and crankcases, effecting a weight reduction of some 20% over the units they replace.

The engines also adopts the ‘Twin Phaser’ continuously variable valve timing described above. In addition, they feature a low friction, maintenance-free chain drive to the camshafts and water pump and are further equipped with a dual detonation sensor to improve sensitivity to engine knock, enhancing maximum performance.

Mated to an M32.6 6-speed manual transmission, the Euro 4 compliant 2.2 litre unit develops 136 KW at 6500rpm, and 230 Nm of torque at 4500rpm. These high power outputs require the use of sodium cooled exhaust valves. The 159 2.2 JTS will accelerate from 0-100 kmh in just 8.8 seconds, and still return 7.3 l/100 km on the open road or more than 30 mpg in the old money.

Diesel Engine

2.4 JTDM 20v

1. 2387cc
2. 5-cylinders, 20 valves
3. Power: 147 kW @ 4000rpm
4. Torque: 400 Nm @ 2000rpm
5. Timing gear: DOHC
6. Transmission: 6-speed manual
7. Top speed: 230 kmh
8. Acceleration 0-100 kmh: 8.4 seconds
9. Fuel consumption:
10. in town: 9.2 l/100 km
11. out of town: 5.4 l/100 km
12. combined: 6.8 l/100 km
13. CO2: 179g/km

Alfa Romeo was first to the market with a JTD Common Rail direct injection diesel engine when the Alfa 156 was launched in Europe during 1997. This crucial lead in diesel technology has not been squandered and, in its latest 20 valve MultiJet guise, the new 5-cylinder 2.4 litre unit is the most powerful engine in the Alfa Romeo JTDM family, with a specific power output of 62 kW/litre.

MultiJet Technology
Within a UniJet engine, a pilot injection raises temperature and pressure inside the cylinder to improve combustion at the time of the main stroke. However, by dividing the main injection into a number of smaller injections, a MultiJet engine affords a fuller, more gradual combustion whilst the amount of diesel burnt at each stroke remains the same; thus facilitating smoother, quieter combustion, reduced emissions and increased performance.

However, a MultiJet engine differs from its Unijet counterpart in two essential areas; the injectors and the electronic control unit.

To facilitate multi-injection, the new injectors can both reduce the time lag between injections from 1500 to just 150 microseconds, and reduce the minimum quantity of fuel injected from 2 to less than 1 cu mm. In tandem, the new control unit modulates injection strategy continually to adjust to changes within three parameters; engine rpm, torque required at any given time by the driver and coolant temperature.

Thus, when coolant temperature is less than 60 degrees and torque requirement low, two small and one large injections are performed. As torque demand increases, the number of injections drops to two; one small and one large. Under conditions of high rpm and high torque demand, only one injection is required whilst, with coolant temperature at over 60 degrees, emissions are minimised with one small, one large, then one small injection in the sequence.

Hence, start-up times and exhaust smoke are reduced, noise levels and vibration are lowered to ensure a quieter drive and improved passenger comfort, fuel consumption is reduced by a further 10% and emission control reduction amounts to 50%; enough to bring the unit within Euro 4 emissions limits.

Derived from the familiar, 2.4 JTD five cylinder 10 valve common rail powerplant, several changes have been made to the latest version of this 20 valve turbodiesel to boost performance and engine torque at low speeds whilst returning impressive fuel consumption figures. The common rail system includes two new control strategies for automatically calibrating and balancing the diesel injection, to both lower noise and reduce vibration, whilst the direct injection pressure has been increased from 1400 to 1600 bar.

The engine also includes a number of new components; a cylinder head with small stem valves to boost inlet air quantity, fractured steel con rods of a new, stress resistant design, a new inlet manifold fitted with a throttle valve at one of the two inlet ports to control air turbulence, a new, high efficiency intercooler, and a throttle valve to prevent shaking if the engine is stalled.

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, whilst the water pump on the cooling circuit is also new.

Turboboost is provided by a KKK 2080 turbocharger with a variable geometry turbine that improves power delivery and also generates very high torque at low engine speeds; 90% of the impressive 400 Nm peak torque is available from between just 1750 and 3500rpm. Mated to an F40 6-speed manual gearbox, this allows the Alfa 2.4 JTD MultiJet to accelerate from 0-100 kmh in only 8.4 seconds, whilst returning a remarkable fuel consumption of just 6.8 l/100 km in the official combined cycle.

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