Air Cooled Vs Oil Cooled Vs Liquid Cooled Engines - Know The Difference!

A motorbike’s cooling system consists of different parts and components, like radiators, hoses and fuel pumps, that work together to prevent the engine from overheating. Cooling systems, essentially, work as a ‘heat shield’ of the bike engine that keeps it running at an optimal temperature and transfers excess heat.

When the fuel mixed with air undergoes combustion, most of the energy (around 70%) is turned into heat, while the rest turns into mechanical energy that turns the pistons. The function of the engine cooling system is to transfer this excess heat while keeping the engine temperature hot enough to maximise combustion efficiency.

Motorbikes have three main types of cooling systems: air-cooled, oil-cooled and liquid-cooled engines. We will learn how they work in the next sections.

Also Read: Engine Protection in Bike Insurance

A motorbike’s cooling system consists of different parts and components, like radiators, hoses and fuel pumps, that work together to prevent the engine from overheating. Cooling systems, essentially, work as a ‘heat shield’ of the bike engine that keeps it running at an optimal temperature and transfers excess heat.

When the fuel mixed with air undergoes combustion, most of the energy (around 70%) is turned into heat, while the rest turns into mechanical energy that turns the pistons. The function of the engine cooling system is to transfer this excess heat while keeping the engine temperature hot enough to maximise combustion efficiency.

Motorbikes have three main types of cooling systems: air-cooled, oil-cooled and liquid-cooled engines. We will learn how they work in the next sections.

Also Read: Engine Protection in Bike Insurance

Here are the most important reasons why the cooling system in a bike is crucial for its functioning:

Transfers Excess Heat

Motorbike engines are much smaller than car engines and are revved quickly when driving in traffic, making them run hotter. The main function of the cooling system is to transfer this heat fast enough that the engine doesn’t overheat. In fact, the cooling system of a bike running at the highest speed dissipates enough heat to heat one small home.

Maintains Optimal Temperature

Most engines run optimally at 93° Celsius (or 200° Fahrenheit). At this high temperature, the combustion chamber is hot enough to completely vaporise the fuel, leading to better fuel efficiency. In addition, the engine oil stays thin (lower viscosity), helping the engine parts move more freely. Therefore, the cooling system quickly heats the engine and maintains the optimum temperature.

Prevents Damage to the Engine

Both cold and very hot temperatures are harmful to the engine in different ways. Cold temperatures lead to faster wear and tear of components and lower efficiency, while very high temperatures lead to warping of parts and excessive thinning of the engine oil. That’s why all vehicles require a cooling system.

Delivers Smooth Rides

Maintaining the optimal temperature is necessary to maximise fuel efficiency and minimise wear and tear. An efficient cooling system prolongs the life of your bike’s engine, lowers its maintenance costs and gives you smoother rides.

Vehicle manufacturers have experimented with various ways to control heat. However, only three have moved on to become popular: air-cooled engines, oil-cooled engines, and liquid-cooled engines. Let us explore how they work.

These are the most basic and oldest types of engine cooling systems. In an air-cooled engine, thin pieces of metal called fins extend from the engine to the outside and transfer heat to the surrounding air. Heat is transferred via fins and ridges connected to the engine framework and cylinder heads. As the bike speeds up, more air passes by the engine, resulting in faster cooling.

Air-cooled engines also have horizontally opposed cylinders, facing away from each other on opposite sides to allow air to flow more freely. Some cooling systems may also use ducts around the engine to help air flow into hotter areas. Due to their simplicity in design, air-cooling systems don’t use parts like radiators, water pumps, hoses or any coolant, resulting in lower engine weight.

Examples of Air-Cooled Bikes

• Yamaha FZ25

• Royal Enfield Bullet 350

• Hero Xtreme 160R

• TVS Apache RTR 160

• Hero Super Splendor

Also Read: Royal Enfield Bullet 350 vs Classic 350

Oil-cooling systems use engine oil as the medium for engine cooling. These engines have a hybrid system of air-cooling and oil-cooling using a part called the motorcycle oil cooler, which works like a smaller version of a radiator. These systems are typically used for vehicles where air-cooling works well for regular functioning, but an additional cooling system is needed for a performance boost.

In oil-cooled engines, the engine oil has dual functions- lubricating engine parts and transferring heat to the outside. The oil absorbs heat from the cylinder walls and pistons as it circulates and gets pumped to the externally-mounted oil cooler. As air passes over the oil cooler, it cools down the engine oil, which is recirculated back into the engine. Compared to regular bikes, oil-cooled bikes have additional engine oil capacity and flow speed.

Examples of Oil-Cooled Bikes

• Royal Enfield Meteor 350

• Bajaj Pulsar NS160

• TVS Apache RTR 200 4V

• Royal Enfield Continental GT 650

• Bajaj Avenger Street 160

Liquid-cooling systems are used in large-capacity and expensive motors. These engines use a complex cooling system and a mixture of water and coolant to remove heat from the engine. The coolant is circulated throughout the engine through tubing adjacent to the hottest spots. The coolant is pumped to a radiator installed in front of the engine and behind the bike’s front wheel.

The radiator acts as a heat exchanger for the engine and exposes the hot coolant to outside air via thin aluminium fins and sometimes fans. Upon cooling, the coolant is pumped back into the engine, and the whole process repeats. Liquid-cooled engines can perform reliably at ideal temperatures in both hot and cold climates.

Examples of Liquid-Cooled Bikes

• Bajaj Dominar 250

• Yamaha R15 V4

• Bajaj Pulsar NS200

• Hero Karizma XMR

• KTM 390 Duke

Also Read: Bajaj Pulsar NS200 Insurance

Before going into the differences between oil-cooled vs air-cooled vs liquid-cooled engines, let’s understand the advantages and disadvantages of each option.

Air-Cooled Engines

Pros

• Their simplistic design makes these engines the most affordable, which lowers the overall cost of the bike.

The lack of specialised components also lowers the engine weight, which improves performance and fuel efficiency.

• Of the three engine types, air-cooled engines have the least maintenance and part replacement costs.

• Their simplicity makes it possible for most mechanics to do repair jobs.

• The low price and running costs make them ideal for rural parts of the country.

Cons

• These engines are prone to overheating in hot climates and during intense operations, making them problematic in most places.

• The engines lose effectiveness when the bike is stationary for long periods.

• The cooling efficiency of these engines varies in different environments and running speeds.

• Air-cooled bike engines tend to be noisier compared to the other engine types.

Oil-Cooled Engines

Pros

• These offer faster and more efficient cooling compared to air-cooled engines.

• No separate coolant solution is required, as oil-cooled engines use the same engine oil as used for lubrication.

• The oil-cooling system maintains a balance between simplicity and efficiency. This results in better cooling than air-cooled engines and lower costs than liquid-cooling systems.

• Oil-cooled engines are used in a wide variety of bikes and other vehicles.

Cons

• Unlike air-cooled bikes, oil-cooled bikes require regular maintenance and oil changes.

• When the engine gets too hot, the engine oil loses viscosity and effectiveness.

• As the cooling system is dependent on the bike’s speed, it cannot be installed in high-performance sporting and racing bikes.

Liquid-Cooled Engines

Pros

• Of all the three engine types, liquid-cooled engines are the most effective at maintaining optimal temperatures.

• These engines maintain Constant operations at different temperatures, operating time and bike speeds.

• Bikes with these engines perform well in long-distance rides, high RPMs (revolutions per minute) and aggressive speeding.

• Due to additional insulation around the engine, liquid-cooled engines run quieter and more smoothly than air-cooled and oil-cooled engines.

• These engines are also more fuel-efficient and environmentally friendly.

Cons

• These cooling systems are more difficult to manufacture due to their complexity.

• Their increased complexity and number of parts make bikes with liquid-cooled engines more expensive.

• Since these engines rely on several hoses, gaskets and seals, they have a higher potential for leakage and the need for regular maintenance.

• Not every garage and technicians are capable of repairing complex engines.

Potential buyers will want to know which one among air-cooling, oil-cooling and liquid-cooling systems is better. Check the table below to know the key differences based on different parameters:

Also Read: Different Types of Motorcycle Engines

When choosing between the different cooling systems, consider your driving conditions, riding style and performance needs. You should also consider your initial budget as well as maintenance and servicing costs. Here are the situations when you can choose each engine type:

Choose an Air-Cooled Engine When

• You ride a motorbike across small distances.

• You live in a place with moderate temperatures.

• You live in rural areas without access to expert mechanics.

• Costs are your utmost priority.

• You are a beginner rider and are looking for a simple bike.

Choose an Oil-Cooled Engine When

• You are looking for a mid-range bike.

• You live in extremely cold climates where normal coolants might freeze.

• You don’t have the budget for a premium bike but want a better bike for riding in hot climates and heavy traffic.

• You want a smaller capacity and a more lightweight option compared to premium bikes.

Choose an Liquid-Cooled Engine When

• You live in a very hot and humid region where other engine types don’t work well.

• You want a high-performance bike with superior power and torque.

• You want a high-capacity bike for long-distance touring.

• The budget is not your biggest constraint when choosing a bike.

• You don’t mind higher maintenance costs to get superior performance.

Knowing the functionality of the various parts of your beloved bike, like its cooling system, can help you drive the best performance out of it. If you are looking for a budget-friendly and simple option, choose an air-cooled engine bike. For better cooling and performance, you can choose oil-cooled and liquid-cooled engines. However, regardless of the bike that you buy, it is important to secure your new bike by getting bike insurance online.

The best bike insurance offers sufficient coverage to cover the entire cost of your bike while keeping the premium amount affordable. To legally ride on Indian roads, a third-party two-wheeler insurance online is mandatory. For efficient protection against legal liabilities arising out of crashes and accidents, TATA AIG’s Third-Party Bike Insurance is the perfect choice. Enjoy quick claim settlement, online purchase and renewals and transparent processing on your third-party bike insurance with TATA AIG..