| The 185 bhp 2.2 JTS and the 160 bhp 1.9 JTS
The 4-cylinder engines of the Alfa Romeo 159 Sportwagon are extremely light because they have aluminium cylinder heads and crankcases (they are approximately 20 kg lighter than the engines they replace). 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 engine 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 220 km/h and accelerating from 0 to 100 km/h in 9.0 seconds. Torque is also excellent on the 1.9 JTS (190 Nm - 19.4 kgm at 4,500 rpm), and 88% 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 210 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 degrees 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 Romeo 159 Sportwagon 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 have 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. And 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 Q4 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 camshaft.
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