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 body with a 72 mm throttle valve is mounted on this casing. And lastly, 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;
- engine block 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 fuel consumption and emissions;
- EOBD;
- 4 lambda sensors to control emissions;
- dual 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 includes 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 sensors 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.
Lastly, 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 features a single ignition coil per cylinder.
185 bhp 2.2 JTS
The 4-cylinder engines fitted to the Alfa Brera are extremely light because they have aluminium cylinder heads and crankcases (they are approximately 20% lighter than the engines they replace). The timing gear control is also particularly advanced, featuring a system of rocker arms and rollers, which significantly reduces dispersion due to friction in the cylinder head, and the 'Twin Phaser' continuously variable valve timing system on the intake and exhaust valves, which optimises power output, torque and fuel consumption. In detail, 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 8.6 seconds.
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