The innovative twin-cylinder engine, developed by Fiat Powertrain Technologies, is the outcome of a philosophy that focused on reducing fuel consumption and, as a consequence, CO2 emissions, in respect of future Euro 5 and Euro 6 emissions standards, with the same performance as a large engine.
The concept behind this new engine is the downsizing from a conventional 4-cylinder engine to a 2-cylinder turbocharged engine that incorporates the innovative MultiAir electronic inlet valve control system. In addition to advantages in terms of consumption, the twin-cylinder engine also results in a 20% reduction in weight and 25% in volume inside the engine bay compared to a 4-cylinder engine with the same power output.
The maximum output achievable by the new twin-cylinder engine, in the Mono Fuel petrol version, is 105 bhp (a 65 bhp aspirated version, also equipped with the MultiAir system, is also under development). The SGE engine family adopts a crankshaft balancing system that significantly reduces vibration and noise levels compared to other 2- and 3-cylinder engines.
The innovative MultiAir system controls the air in controlled-ignition petrol engines without the usual throttle valve, and therefore with a greater degree of flexibility than mechanical timing systems. This electrohydraulic valve activation technology is based on the insertion, between the camshaft and the engine inlet valve, of an amount of oil (high pressure chamber) that can be varied by a valve, which in turn is controlled by a specific electronic control unit.
This allows the opening profile of the valve to be modified in response to the request for air from the engine and to the running speed. Different strategies can be employed (Early Inlet Valve Closing – EIVC, Late Inlet Valve Opening – LIVO, or Multi-Lift) to optimise combustion efficiency, with considerable benefits in terms of power output, torque, consumption and emissions. Another advantage of this system is the fact that the air pressure upstream of the valves is always constant. This characteristic allows the torque response of the engine to be increased without any delay, on both an aspirated and a turbocharged engine, increasing the ‘fun to drive’ factor.
On the Panda Aria the new twin-cylinder engine is combined with a dual fuel management system, with petrol and a mixture of methane (70%) and hydrogen (30%); this solution also helps to reduce polluting emissions by guaranteeing more efficient, complete combustion. It also makes it possible to increase the engine’s thermodynamic efficiency and to achieve combustion stability values that are better than those possible with methane alone, in certain operating conditions. This means that methane-hydrogen vehicles represent a step forward for an existing technology that is open to further refinement and new applications.