Why are carburettors not used anymore?

Carburettor and fuel injection are the two types of fuel delivery systems from the fuel tank to the engine. Before we discuss why carburettors are not used anymore, you can quickly study carburetor vs fuel injection to understand the benefits of a fuel injection system.

Carburettor system of fuel delivery

To understand carburettors, we need to understand air and gas. When oxygen combines with the fuel, it begins oxidation. When that happens rapidly, it produces light, heat and fire and we call that combustion.

To continue this reaction of combustion, we need to feed it oxygen. The carburettor does this mixing. FIre can’t survive without oxygen and so a carburettor feeds it oxygen. We will learn about the detailed working mechanism of carburettors now:

Working of a carburettor

The carburettor is like the heart of an internal combustion engine. It is a part of the petrol engine where a controlled amount of fuel is atomized with controlled amounts of air and is sent to the engine.

The carburettor uses the principle of a sprayer. When the piston of the pump is pushed inside, the velocity of air increases and the pressure reduces at the outlet of the reservoir. The liquid at the reservoir is at higher atmospheric pressure. This pressure difference results in the rising of the liquid.

The principle of sprayer is achieved here in the air passage- air travels from the air filter to the engine. In the middle is a constriction which acts like a venturi and the top is at low pressure. This causes the fuel to rise and it emerges at the top.

The fuel mixes with the air at the above step and the fuel-air mixture is then sent to the engine. To meet the engine requirements under varying conditions, the following circuits are used in carburettors:

Fuel inlet and fuel circuit

This circuit controls the fuel level in the float chamber,

Starter circuit

This circuit helps in starting the cold engine.

Pilot circuit

This is in action when the engine is idling, or at slow or medium speed.

Main circuit

The main circuit is used when an engine is running at medium and high speeds.

When the throttle is opened, the vehicle achieves a speed. According to the speed, the carburettor engages the appropriate circuit for that speed.

That was very technical and enough physics. Let’s see why the carburettors were phased out slowly.

Carburettors vs fuel injection

Let us see why fuel injection system is better:

What you can feel by yourself:

• Engine performance

The fuel injection system is controlled by ECU and everything is automatic. But carburettors need to be adjusted manually for the right air-fuel mixture. The automatic fuel injection gives better engine performance.

Let me elaborate this with an example of a popular bike TVS Apache RTR 160 4V. It is available in two versions- carburettor and EFI. The carburettor version produces 16.5 PS power at 8000 rpm and the EFI or electronic fuel injection version produces 16.8 PS of power. The top speed is also more in the EFI version.

• Fuel efficiency

This is one of the most important points of the fuel injection system. If you ask any less knowledgeable person about the fuel injection system, even he will answer it is more fuel-efficient. Earlier Fi bikes were only known to be more fuel-efficient than anything else.

As the fuel injection system is ECU controlled so there is no chance of setting error. They senf fuel like fine sprays which are very efficient and there is no sending of extra fuel. It sends just what the engine needs. Finally, you will get better mileage with a Fi vehicle.

• Better cold start

Carburettor bikes have a problem when starting cold. You may have seen that every old bike or scooty needs more cranking in the winter season. But in Fi bikes and scooters, there is no problem with a cold start. They start up quickly.

What you don’t know is going behind:

• Carbon emissions

The fuel-injected system has come into play with BS6 bikes. Now, almost all bikes have a Fuel injection system with BS6 norms being implied. This system produces fewer carbon emissions as compared to carburettors. This is so because there is no unnecessary burning of fuel in the fuel injection system. Only the needed amount is burnt.

• Fuel according to need

Suppose you are riding in traffic and constantly applying brakes and moving slowly. This time you don’t need more fuel than air (lean mixture). Again on the highway when you are riding at high speeds, you need a rich mixture of fuel.

Controlling this wasn’t possible in carburettors and so they are phased out now. Fuel injection can sense this and send fuel accordingly. So, it is always better and more economical to have a fuel injection system installed.
So, to conclude, carburettors were phased out and replaced with fuel injection as they are more advanced and do their job better. You can check out the necessary car accessories and install them in your car without any effort from here.

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