Fuel Injectors Versus Carburettors

There has been a competition between the two fuel supply systems since 1980, the day first Fuel Injection System was introduced. Almost all Cars have shifted to Fuel Injectors and most of the Motorcycles are now available in two variants, Carburetted and Fuel Injected. Since the growing market and the demand  controls the technology, many still love and miss the Two Strokes and Rotary Engines. Same could be the case with Carburettors, thus before they go obsolete we are here to tell you about how both these systems work and what sets them apart.


In the 1730s, a Swiss mathematician and physicist, Daniel Bernoulli, discovered that air pressure decreases as velocity increases and it occurs in a consistent way which helps move the air through a restricted section of tube, resulting in increased air flow with pressure drop. In 1797, an Italian physicist named Giovanni Venturi designed a tube that had a much smaller inlet at that restriction, in that low-pressure area. That inlet allowed the tube to pull liquid into the flowing air, and that is what a Carburettor is and does.

As the velocity of the air increases through the narrow area, a low pressure pocket is created, which in turn facilitates drawing fuel from a jet placed near the venturi through suction. The amount of air sucked into the Carburettor is decided by Throttle Valve at the end of the tube connected to the cylinder. The Throttle Valve is connected to the accelerator which controls the Air-Fuel Flow.

The fuel jet placed near the venturi draws its fuel directly from the fuel tank via a float chamber, which is a small reservoir for fuel, with a float valve which cuts fuel supply when it’s full and resumes the flow when the jet is drawing fuel from it. Then the air-fuel mixture is then supplied to the cylinder where combustion takes place.

Fuel Injection

As simple as Carburettor’s working, Fuel Injection is equally complex, comprising of complex set of electronics and sensors.

In Carburetted Systems the fuel is drawn from the tank, while in a Fuel Injected system it depends on a fuel pump installed inside the tank for a finer and precise control over fuel flow. The Fuel Injection nozzle also goes directly inside the Combustion Chamber to make a homogeneous mixture of fuel and air allowing for very efficient and clean combustion.

Fuel Injection is controlled through an ECU (Electronic Control Unit), which is programmed to do complex calculations at a very high frequency to deliver the best air-fuel mixture possible. Based on variety of parameters such as engine speed, throttle position, engine temperature, load, etc. the ECU directs the injectors to let in the right amount of fuel with every intake stroke to facilitate the most efficient combustion.

Going through the above explanation you can understand that Fuel Injection system is superior to Carburettor, but both the systems have their distinct advantages and disadvantages.

Merits of Carburettors

  • Cost less, simple in operation and easy to repair or replace.
  • Users can tune them to their own requirements.
  • Engine remains untouched whenever Carburettors needs to be serviced and replaced as it is not an integrated part of the engine.

Demerits of Carburettors

  • Not the most efficient system.
  • Low Acceleration response due to slight lags.
  • Components are more prone to damage.
  • As the Air-Fuel mixture fluctuates it affects the engine smoothness.


Merits of Fuel Injection

  • Optimized air-fuel mixture and highly atomized which allows for cleaner and more efficient combustion.
  • Sharper Acceleration response.
  • Better fuel efficiency and marginally more power than Carburetted systems.
  • Typically maintenance free and does not break down (mostly).

Demerits of Fuel Injection

  • More expensive components than Carburettors.
  • Cannot be repaired with simple tools, it has to be replaced, which is expensive.
  • Air-fuel mixture cannot be customized, unless you go for custom ECU maps, which again is expensive.
  • Requires a skilled technician.

With this we conclude our Article and hope we further increased the depth of your Automobile and Motorsports Vision. If you want to know more feel free to comment down below.

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