Difference Between Diesel Engine and Gasoline Engine

The automobile industry has a close connection with the human community. It is the mode of transportation most of them use for their commutation.


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It can be a means of public transport or a private vehicle, the variation of the cost impacts the lifestyle most of the time.

The private vehicle car companies have come up with the reduction of prices and a lot of marketing strategies to lure customers to buy their product.

The first question that people ask while they see a new vehicle is about the mileage that the vehicle offers. Though a lot of reasons are there which impact on the mileage, the sole reason the performance of the vehicle is determined is with the engine.

There are petrol engine vehicles, diesel, and gasoline. They have their differences in performance and people opt for a specific engine completely depends on personal preference.

The current trend is purchasing either a diesel engine or a gasoline engine vehicle. The reason can be many, price, mileage, smoothness, but it is prudent to understand the differences between the two engines.

Diesel Engine vs Gasoline Engine

The difference between a diesel engine and the gasoline engine is the injection and combustion process. In a diesel engine, the air is compressed first and the fuel is injected for the combustion to happen, while in the case of a gasoline engine, the fuel is mixed with air first and then compressed by the pistons to create a spark from the sparkplugs for the combustion to happen.

Diesel Engine vs Gasoline Engine


Comparison Table

Parameter of ComparisonDiesel EngineGasoline Engine
Combustion ProcessThe Air is compressed first and then the fuel is injected for the combustion to happenThe air and fuel are mixed first and then injected for the sparkplug to ignite it which causes combustion.
Spark PlugDiesel Engine does not have a spark plug to ignite.Gasoline Engines requires a spark plug to ignite and it is an integral part of the carburetor.
Fuel EfficiencyThe fuel efficiency of a diesel car is more compared to a gasoline engine.The fuel efficiency of a gasoline engine is less compared to a diesel engine.
Engine KnockingDiesel engines make more noise because they have more torque.Gasoline engines are quieter compared to the diesel engines
Electrical EquipmentDiesel engines do not require any electrical equipment but need an alternator.The gasoline engine requires a coil, distributor, and alternator.


What is Diesel Engine?

A diesel engine is a type of engine in which the ignition of the fule happens by the increased temperature of the air in the cylinder owing to mechanical compression. A diesel engine is also called as Internal Combustion Engine (ICE)

Diesel engine functions only by compressing the air. It does not require any sparkplugs for ignition.

The compression of air increases the temperature of the air inside the cylinder and the diesel is injected into the combustion chamber which ignites spontaneously.

The process of the mix is called a heterogenous air-fuel mixture as the fuel is dispersed unevenly in the air.

The diesel engine is considered to have the highest thermal efficiency. This is due to its high expansion ratio and also the lean burn which facilitates heat dissipation by the excess of air.

Diesel engines were initially used in steamboats. Diesel engines can be designed as two-stroke as well as four-stroke cycles.

The usage of diesel engines in ships started earlier than the trucks and other heavy vehicles. The advent of diesel engines for domestic vehicles came into existence later.

The diesel engine has high torque and it may cause a lot of noise compared to its other counterparts.

The diesel engine may also have a unit called glow plug which enables to start the engine during cold seasons.

Diesel Engine

What is Gasoline Engine?

The gasoline engine is a type of engine which compresses and mixes air and fuel which happens mechanically, while the sparkplug ignites the fuel. It is also an Internal Combustion Engine (ICE) but it requires a sparkplug.

The gasoline engine works on Otto Cycle where air and fuel are mixed in the carburetor. The fuel is ignited with an electric spark from the sparkplug.

The power production in a gasoline engine is lower and highly volatile fuels are utilized in the gasoline engine. Gasoline Engine is named for low maintenance but the fuel consumption is high.

Gasoline engines can be found using light motor vehicles like cars, motorcycles. The noise from the gasoline engine is very low and at times quite as well.

Gasoline engines have faster rotation speeds as it has lighter pistons, connecting rods and crankshaft. It is also since gasoline burns quickly.

Gasoline engines can be designed as two-stroke as well as four-stroke engines. Gasoline engines are either have 1 to 6 cylinder formation or 2 to 12 cylinder formation depends on the design.

Petrol engines can be cooled easily. It is done through air cooling methods.

Certain gasoline engine designs also have a liquid coolant is present in the radiator. The liquid was earlier water, while these days many coolants have come to replace water as quick cooling methods.

Gasoline Engine

Main Differences Between Diesel Engine and Gasoline Engine

  1. Both the engines have their benefits for the automobile industry, however, there are many differences between them. The main difference between a diesel engine and a gasoline engine is the injection and combustion process. The diesel engine has the air compressed into the cylinder where the fuel is injected and it ignites spontaneously, while the gasoline engine can compress both air and fuel first which gets compressed in the cylinder which has the sparkplug to ignite the fuel.
  2. Diesel engine functions by compressing the air and it does not require a sparkplug to ignite the fuel while the gasoline engine requires a sparkplug in the carburetor. 
  3. It is always observed that the fuel efficiency of a diesel engine is more than the gasoline engines
  4. Diesel engines are majorly used in heavy motor vehicles like trucks and heavy equipment movers while gasoline engines are used in light motor vehicles like cars, motorcycles.
  5. The diesel engine gives out noise while the gasoline engine is smooth and quiet.
Difference Between Diesel Engine and Gasoline Engine


  1. https://ehp.niehs.nih.gov/doi/abs/10.1289/ehp.94102s485
  2. https://www.osti.gov/biblio/5967871
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