Carburetor Vs Fuel Injection – Which Is the Best?

When comparing carburetor vs fuel injection, the latter will always be the winner. And you already know that.

But you are here to understand how it is better. We are going to describe the benefits of fuel injectors. But we will also note the benefits of carburetors and why they might still interest you.

Before getting into the difference, let me remind you that there are many types of carburetors and fuel injection systems. So, we are not gonna be talking about the extremes. We will focus on their average capabilities. However, we consider the direct injection system as the average for fuel injectors.

How Carburetors and Fuel Injectors Differ

Carburetors and fuel injectors are different systems. Although they do the same work, the process is totally different. So, keeping a side-by-side comparison is hard. So, we did the next best thing here.

But we can assure you that there isn’t an aspect that we haven’t included here. From a non-academic point of view, we have everything here that the two components differ in.

Control Over the Air/Fuel Ratio

CarburetorFuel injection
No controlBetter control

This is the biggest driving force behind the success of the fuel injector. So, let’s talk about it first.

In carburetors: The carburetor is a mechanical device that uses air pressure created from the engine to mix air and fuel. Here, the air-fuel ratio is determined by the air pressure created from the engine, the venturi, and the fuel jet structure.

But there are plenty of other external reasons that can change the air/fuel ratio against our will. They are-

  • Ambient temperature
  • Barometric pressure
  • Altitude
  • Humidity

And this ratio also depends on some components of the engine other than the carburetor, like-

  • Header type
  • Header length
  • Camshaft changes
  • Gearing and tire changes
  • Track length

Although four-barrel carburetors give you some level of control, for the most part, you have no control over the richness of your air supply.

This reduces engine performance by undersupplying the engine. Oversupply will increase the emission levels. Not to mention the cost and engine damage it would cause.

In fuel injection: The fuel injectors are part of the fuel injection system. This system collects data from various sensors, like-

  • The required amount of fuel under different pressure levels in the fuel pump
  • Amount of air taken in measured by the airflow sensor
  • Air mass that is calculated from the air pressure
  • Engine speed from the crankshaft speed sensor
  • Knock effect from the knock sensor
  • Temperature of the engine from the temperature sensor
  • Camshaft speed from the camshaft sensor
  • Exhaust gas temperature from exhaust sensor

After the driver pushes the accelerator paddle, the circuit board of the engine management system calculates the amount of fuel needed to achieve the required RPM of the driver. They calculate it with the data from the sensors mentioned above. And they do it for each cylinder and inject that precise amount.

Hence, you can meticulously control the air-fuel ratio. It gives you the best engine performance and the least emissions.

Fuel Efficiency

CarburetorFuel injection
Less efficientBest efficiency

This is the reason carburetors are dying in the market.

Carburetor: As you can’t control the air/fuel mixture, often the carburetors supply more fuel than necessary. The richness can be caused by-

  • Hotter air
  • Higher altitude
  • Thinner air
  • Higher humidity
  • Orientation of the vehicle

All of these cause the air pressure to increase and draw more fuel from the jet than necessary. Therefore, it is not the best when it comes to fuel efficiency.

Fuel injection: You have full control over the air/fuel mixture. Plus, the inbuilt circuit calculates for you the amount of fuel you will need.

And in direct fuel injection, the air is sprayed with about 5000 PSI. So, you have the perfect fuel-efficient engine with fuel injection. The high atomization also allows cleaner combustion and greater power. But you can also have a richer fuel mixture if you want.

Cost, Repair, and Replacement

CarburetorFuel injection
Less ExpensiveThe whole system is more expensive

This is where the carburetors has a point.

Carburetors: Nowadays there are more carburetors in the market than there is demand. And decades of high demand for it made its manufacturing cost very low. So, getting a new one online is very easy. Plus, it is so easy to maintain that if something goes wrong, you can fix it yourself on the spot.

Fuel injection: The fuel injection is the name of the system. If you are only thinking of the sprayer for the whole fuel injection system, then you are mistaking. And maintaining the system and getting replacements can be very expensive.

I would like to add that every penny of the money you spent here is worth it. Getting a fuel injection system means-

  • No leaking petcock
  • No flow pull
  • No gummed up jets
  • Less damage from knock effect
  • And you don’t have to deal with the choke lever

And they don’t need maintenance and repair regularly.

Tuning

CarburetorFuel injection
Easy to tuneDoesn’t need tuning

Some carburetor fans might say that this is a plus for carbs. But they fail to understand the main function of the fuel injection system is auto-tuning.

Yes, the carburetor is easy to tune, but the fuel injection doesn’t need tuning, making it far better.

Throttle Response

CarburetorFuel injection
Slow responseFast response

Carburetors are mechanical devices. Hence, it takes time to react to your throttle, no matter how great the carb is.

However, fuel injections are electric devices giving you a virtually instant response. That response paired with the data-driven injection creates the fastest reaction.

Starting

CarburetorFuel injection
No skill requiredRequires more skill

In a direct fuel injection system, the injector directly sprays fuel in the cylinder. This can cause flooding of the cylinders when starting. And this problem gets a little complicated when we consider different engine types. That’s why they require a little experience when starting the engine. Carbs don’t have such problems.

Versatility

CarburetorFuel injection
Incompatible with some fuelsCompatible with almost all liquid fuels

Carburetors can’t be used with diesel vehicles. It is also incompatible with biofuels like ethanol which are getting prominence in our country. They also don’t run with many additives.

On the other hand, fuel injection systems work with all kinds of liquid fuel and additives.

Emission

CarburetorFuel injection
Can’t meet the emission standardsPlays a big role in cutting down the emission

Although this issue is intertwined with the air/fuel ratio, it reserves a separate mention.

This is the biggest reason why fuel injectors are getting killed by carburetors. Carburetors can’t control their fuel ratio, often supplying a richer mix than needed.

They also have a lot of unburnt gas and bad exhaust management. Even when carburetor engines are not running, they are wafting gas vapors into the air from the open vents, flow poles, and gas tanks.

Fuel injectors have a very low air/fuel ratio range that helps to cut down on the emission.

Electricity and External Systems

CarburetorFuel injection
Doesn’t need electricity and external systemsDependent on electricity and external systems

Carburetors are entirely mechanical systems. If there is anything wrong with it, you can fix it in the middle of the road.

But that is not gonna be happening with the fuel injection. Especially if there is something wrong with the electrical system. They are also dependent on external sensors to work right. Those systems were mentioned in the air/fuel ratio section.

Lean Combustion

CarburetorFuel injection
Lean combustion is impossibleLean combustion is impossible

You need to have a certain amount of fuel-rich air just near the spark plug in the cylinder to have lean combustion.

That is obviously not possible with carburetors. But direct fuel injectors can spray a small amount of fuel near the spark plug to acquire the richness to make lean combustion possible.

Cleaning of Internal Components

CarburetorFuel injection
Not that great for cleaningBetter for cleaning internal components

Carburetors can clean the engine insides with fuel additives. But they are not that efficient.

Sprayers can target different areas to clean them with both additives and higher pressure. Manufacturers use a combination of port injection and direct injection to clean cylinders, fuel rails, and valves.

Final Thoughts

We know some people are still fighting the carburetor vs fuel injection comparison. But the reality is, the carburetor has already lost in a head-to-head competition.

Although it might be fun to play with the carbs. But it is just that. A toy for the enthusiasts. A proud part of automobile and aviation history.

BTW, we already talked in this post on motorcycle carburetors and fuel injection specifically. Read it if you need.

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