What is a naturally aspirated engine? The pros and cons of a naturally aspirated engine

We all have heard about the terms naturally aspirated engines, and forced induction engines from vehicle review videos and automobile-related magazines.

What does it mean? What are the advantages and drawbacks of these both?

These are the two ways which use in an automobile engine the sucking air from the atmosphere.

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Atmospheric air(Oxygen) and the working of an automotive engine

An internal combustion engine gets the working energy from the ignition of fuel inside the combustion chamber. Atmospheric air (Oxygen) is essential for any object to burn completely, similarly the presence of oxygen is essential for the ignition process, whether it is a petrol or diesel engine.


If it is a petrol engine, the air is mixed with fuel (Petrol) and sent to the combustion chamber. Here the air-fuel mixture compresses due to the upward movement of the piston. This air-fuel mixture is then ignited with the help of a spark plug to produce energy.

But if it is a diesel engine, only air is compressed in the combustion chamber. Diesel is sprayed into the compressed air with the help of injectors, As a result, ignition takes place, and energy is generated.

From this, whether it is a petrol or a diesel engine, atmospheric air is required to produce energy by burning the fuel. Two methods are commonly used in automobiles to deliver atmospheric air into the engine cylinder.

The first method is to suck the air using the vacuum (pressure depression) inside the engine cylinder. The second method is to pump the air into the engine cylinder with the help of an external force.

The above-mentioned two ways are simply called the naturally aspirated and forced induction types of engines.

Naturally aspirated engines

In a 4-stroke engine, air enters the cylinder during the suction stroke. At this time (Suction stroke) the piston moves from the top dead center (TDC) to the bottom dead center (BDC), which creates a vacuum or pressure depression inside the cylinder. This vacuum (pressure depression) helps to suck the atmospheric air into the engine cylinder. 

If the air enters the engine cylinder only with the help of a vacuum or negative pressure inside the cylinder, such types of engines are called naturally aspirated engines. Therefore, the air coming into the engine has only normal atmospheric pressure.

The naturally aspirated engine is used not only in ordinary cars but also in many performance cars and almost all bikes are run on naturally aspirated engines.

Forced induction-type engines

If the air enters the engine cylinder with the help of an external force, such types of engines are called forced induction engines. Forced induction types of engines are of two types, turbocharged engines, and supercharged engines.

If the engine use turbocharger as the forced induction device it is called a turbocharged engine. If the forced induction device is a supercharger those types of engines are under the category of supercharged engines.

Because of the use of these force induction devices, compressed air enters the engine cylinder, which improves the volumetric efficiency of the engine. It improves the overall efficiency of the engine.

Advantages of Naturally aspirated engine

   Quick response: The naturally aspirated engines are quick in response, the engine responds on time as the accelerator pedal applies.

   Linear power delivery: The power output of a naturally aspirated engine will be linear. The air coming into the engine has only normal atmospheric pressure, so here the chance of pressure variation is minimal.

In forced induction engines, the force induction devices are working by the energy of the engine. So there will create an initial lag because these are working properly after the engine works.

   Easy to repair: This type of engine is relatively easy to repair because here the complicated parts are minimal compared to a forced induction type engine.

   Low cost: The production and maintenance costs are less compared to a forced induction-type engine. The components used for the aspiration are minimal here.

Disadvantages of Naturally aspirated engine

   Poor engine performance: The naturally aspirated engine provide poor performance in high-range areas. The naturally aspirated engine works on atmospheric pressure, the atmospheric pressure in the high-range area is comparatively low.

It reduces the volumetric efficiency of the engine resulting in poor engine performance.


   Less efficient: Here the engine sucks the air with atmospheric pressure. So the volumetric efficiency will be lower in comparison with the forced induction engine.

The lower volumetric efficiency decreases the overall efficiency of the engine. So naturally-aspirated engines are less efficient than forced induction engines.

   Limited alternation: The alternation works are limited to naturally aspirated engines. It means the possibilities like turning or any other methods to increase the efficiency of the engine are limited.

The overall efficiency of a naturally aspirated engine is disappointing compared to a forced induction type. But the plus point is the absence of turbo lag when comparing it with a forced-induction engine. For this reason, some performance cars are still using the naturally aspirated engine.

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