Which of the following statements is true about a four-stroke engine in comparison to a two-stroke engine?
1
Thermal efficiency and part-load efficiency of a four-stroke engine are better than those of a two-stroke engine.
2
Volumetric efficiency of a four-stroke engine is comparatively low, due to less power output.
3
Owing to one power stroke in two revolutions, a lighter flywheel is required.
4
A four-stroke engine only uses the diesel cycle, while a two-stroke engine only uses the Otto cycle.