Why Aren't More Automobile Manufacturers Engineering Two-Cylinder Turbo Engines?
In the automotive industry, the debate over the ideal number of cylinders for engines has been ongoing. This discussion often hinges on the performance, efficiency, and practicality of different engine designs, with two-cylinder turbo engines sometimes being seen as a potential game-changer. However, despite their efficiency in smaller vehicles like the Fiat TwinAir, why have more automobile manufacturers not embraced this design for their cars?
The Case for Three-Cylinder Engines
Interestingly, three-cylinder turbo engines are often considered the ideal configuration. They offer a balance between performance and efficiency, with three cylinders providing a good compromise between power and vibration. Additionally, three-cylinder engines have the best sound quality among all engine types, which adds to their appeal.
Why Two-Cylinder Engines Fall Short
Despite the potential, two-cylinder engines are not commonly used in mainstream automobiles. There are several reasons for this:
1. Rough Running and Durability
Inline twin four-stroke Otto engines, despite the addition of balance shafts, remain inherently rough-running. This is due to the vibration harmonics that occur every 360 degrees. The rocking motion caused by these vibrations makes the engine harder to balance and reduces its overall robustness. Balance shafts, while helpful, use some of the engine's power to operate, leading to parasitic losses that offset the added benefits.
2. Low Power Output
The power output of two-cylinder engines is inherently low. Increasing the size of the cylinders can help, but only to a certain extent. This limitation means that most users prefer engines that offer smoother, quieter, and less tiring driving experiences, even if they are more expensive.
3. Emissions and Regulation Challenges
Another significant factor preventing the widespread adoption of two-cylinder engines is the stringent emission regulations. As the automotive industry progresses, there is a move towards larger engines to comply with new emission standards. Small engines, while they might have low fuel consumption and conventional emissions, often fail to meet particulate and NOX emission requirements under heavy loads. With the implementation of new regulations, these challenges are becoming more pronounced.
Future Developments
Despite these challenges, there are some potential solutions being explored. For instance, active flywheel technologies integrated with hybrid setups might help mitigate some of the vibration issues. However, the complexity of transitioning from motor to generator multiple times per revolution poses practical limitations.
Similarly, advancements in fully camless valving could potentially address some of the emission and particulate issues. Engines like those developed by Konigsegg and others demonstrate potential, but the diminishing returns associated with further control trickery in combustion engines might make electric vehicles a more viable long-term solution.
Ultimately, while two-cylinder engines have their merits, particularly in smaller vehicles, the automotive industry is increasingly turning towards other solutions that meet current and future regulatory requirements. The balance between performance, efficiency, and emissions compliance continues to evolve, shaping the future of automotive engineering.