Carburettor Vs Fuel Injection

With the progress of mechanisms in automobiles, fuel injection systems are gradually winning over carburettor systems for several reasons. Both systems are responsible for passing the air-fuel mixture properly to create perfect pressure during engine combustion.

However, there are sharp differences between carburettor and fuel injection systems. Keep reading to find out.

A carburettor is a device inside the engine that mixes oil and air in perfect ratio during an engine combustion process. The mechanism provides spark ignition to the engine. The components of a carburettor are:

• Venturi
• Idling System
• Throttle Valve
• Strainer
• Idle and Transfer port
• Choke Valve
• Float Chamber
• Mixing Chamber

Types: Carburettors are of two types, fixed venturi and variable venturi. Fixed venturi carburettors regulate the fuel flow with a velocity of airflow. On the other hand, variable venturi controls the raw fuel mechanically and regulates fuel flow with airflow.

Materials: A carburettor has many parts to perform the engine combustion task. Therefore, different parts are made with different materials. However, the main part of a carburettor is made with alloy or aluminium, essentially lightweight. Further, other moving parts are made with stainless steel.

A carburettor is situated between the inlet and induction manifold and compiles air pressure and oil for engine ignition. The working process of a carburettor is as follows:

Step 1: A charged engine forces air into this carburettor

Step 2: In the middle of a carburettor, a venturi, a pipe-like construction restricts this air and increases its velocity

Step 3: The increasing velocity creates a low-pressure pocket that, in turn, helps draw fuel from a nearby jet to the venturi by suction

Step 4: At the end of the venturi, a butterfly valve controls and regulates the air pressure of the pipe

Step 5: Butterfly valve works with a throttle valve that controls fluid flow

Step 6: As the throttling process moves forward, the mixture of air and fluid enters the induction manifold, and combustion happens

Fuel injection is an important mechanism that helps in low fuel consumption. It is common in automotive engines in the form of a fuel injector. Therefore, it is an electronically-regulated system that injects a minimum amount of atomised fuel into the cylinder. The components of fuel injection are:

• Fuel tank and supply pump
• Fuel heaters and coolers
• Fuel filter
• Accumulator
• High-pressure pump
• Fuel injector and fuel injection nozzle
• Fuel metering
• Nozzle needle control actuators

Types: There are four types of fuel injection; throttle body or single-point injection, multipoint fuel injection, direct injection, and sequential fuel injection. A single-point injection is the most basic fuel injection and just a replacement for a carburettor. 

A multipoint fuel injector injects fuel into each cylinder with different injector nozzles.  The direct fuel injection allows diesel and petrol engines to utilise fuel more efficiently, thereby leading to more power. Lastly, sequential fuel injection is an advanced form of multiport fuel injector that works for efficiency and emission improvements.

Material: Fuel injectors are made with carburised or maraging steel to manage high temperatures.

Fuel injection is monitored electronically; therefore, it calculates and gives the most efficient air-fuel mixture and is responsible for a smooth and clean combustion process. A fuel injection system works in the following process,

Step 1: A fuel pump draws the fuel from the tank with superb control

Step 2: This atomised fuel enters the combustion chambers as FI mist through nozzles

Step 3: as it reaches the chamber, combustion happens