Petrol engines: more power and torque
State-of-the-art compact three-cylinder engines are installed at the rear of new smart fortwo. For the petrol engines, the engine capacity has been increased from 0.7 to 1.0 litres. There are two naturally aspirated engine versions to choose from, delivering 45 or 52 kW (61 / 71 bhp) respectively, and a turbo engine rated at 62 kW (84 bhp). In addition to the increase in power, the maximum speed has also been increased – to 145 km/h.
The all-aluminium engine was developed in cooperation with Mitsubishi, and is produced in Japan. It has been further developed for use in the new smart fortwo.
The engine is mounted transversally in front of the rear axle, and is slanted at an angle of 45 degrees towards the rear. The cylinder barrels take the form of grey cast iron liners. Gas exchange is controlled by four valves per combustion chamber. The valves are controlled by separate intake and exhaust camshafts, via bucket tappets.
To allow high torque to be developed even at low engine speeds, the intake camshafts can be twisted electrohydraulically against the exhaust camshafts (variable valve control). The camshafts are driven via a maintenance-free timing chain.
Because the masses being moved are low, there is no need for a balancer shaft – which would reduce the output of the engine. However, in the turbo version there is a torsional vibration damper on the crankshaft.
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