The recent availability of small liquid cooled engines now provides the choice of air or liquid cooling down to smaller sizes than was previously possible. Although air cooled engines should have an inherent size advantage, installed package size and weight of existing air cooled and liquid cooled engines is equivalent. Noise levels of air and liquid cooled engines, with their cooling systems, is also equivalent. Air cooled engines are superior to liquid cooled engines in having higher reliability and lower maintenance requirements associated with the cooling system. Power cylinder durability is equivalent for engines using either of the cooling methods, but air cooling provides a superior durability for rough handling or rugged environment applications.