Difference between Air cooled engine and Water cooled egine

Author：Newtec Power  Date：2014-10-25 22:16:39

For diesel engines,there are two kinds of cooling system,one is air cooled type,other is water cooled type,Every engine needs a cooling system to eliminate engine heat. Left to their own devices, engines would otherwise destroy themselves. 

The main differences between air cooled and water-cooled outboard engines are how they work and maintenance issues.

Air cooled engine uses airflow directed at fins on the cylinders and heads is the cooling medium: heat is transferred directly to the air. The air comes either by natural convection or by forced air.

Water cooled engines circulate coolant around the heads + cylinders though a surrounding water jacket, and use a separate high-efficiency radiator for the final heat exchange to the air. (Marine engines are a bit different - they use the surrounding water instead, either directly or though a water-to-water heat exchanger.) 

Air cooled engines are simpler, lighter and easier to maintain as they don't have the 'wet' cooling system elements. They excel in cold climates where coolant freezing can be a problem. However, air cooling is less efficient due to the low heat capacity of air so these engines suffer from hot spots which reduces power, increases emissions and shortens their life. 

Air cooled engines are also considerably noisier - both from the engine directly and also from the air blower cooling fan if used. 

Water cooled engines take advantage of water's high heat capacity to efficiently carry away the heat. So they offer the best control over temperature allowing for more aggressive / efficient tuning and optimal head design. While they have increased near-term maintenance costs (coolant, water pump, hoses, etc.) they make up for it in a longer-lived engine core (longer time between overhaul.) 

Water cooled engines are also quieter due to the insulating properties of the water jacket and the lessened airflow requirement. 

Water cooling also permits more flexibility in engine architecture and installation since there isn't a need to duct cooling air directly to the cylinders.

In total,Water cooled engine is much more stable than Air cooled engine,and the lifetime is much longger too,but the size of Water cooled engine is bigger than air cooled engine.

• Previous：No More!
• Next：Components of Diesel Generator Set