Over the years, the very need to reduce the dependence on non-renewable energies has been modeling the manufacture of automobile engines. In the first vehicles of history this was not a concern of the manufacturers... and continued without being it until the mid-70s, with the oil crisis .

It was then that society and manufacturers realized that they could not waste fossil fuels. An urgent and progressive action was necessary, which would reduce the excessive consumption of fuel. In this way, gasoline car systems have evolved from waste, to be much more efficient. This has been the path to increasingly frugal and less polluting engines:

Carburation or injection

The carburation system has been for years the system par excellence in gasoline engines. It is a mechanical system that does not require the management of a switchboard , as it prepares the air-fuel mixture in the admission itself . When the air enters the intake and crosses the carburetion system, it works the same way as a paint sprayer . The more air enters, the greater the force that pushes the fuel. It is an old system but in the end it never fails . Although it is not efficient.

The carburation was surpassed by the current system par excellence, fuel injection . A system that injects fuel directly into the combustion chamber , or in the case of most diesel engines, into the combustion chamber (located in the cylinder head).

By the way. Carburetion systems were only used with gasoline engines. In diesel they cannot be used, because they cannot work with the fuel flow in the intake. So they use an injection system, developing the flow in the prechamber, so that, when diesel enters the area, it can carry out its work.

Advantages of injection systems

Efficient consumption

Unlike the carburetion system, the injectors are regulated by the control unit normally (although we will see that there are other ways). The advantage is that in the engine, there are times when the air intake does not match the flow of gasoline. Carburetion is regulated by air pressure, but at low revolutions, not so much fuel volume is necessary. If we add all those moments in which gasoline is wasted, the savings are considerable.

Higher performance

Another problem with carburetion, although it is recognized as a competition system, is that, basically, the performance is not entirely good . Basically, gasoline is introduced into the jet cylinders, that is, it does not cover the entire surface equally. The injection allows to cover all the zones of the internal chamber, where the cylinders are housed, thus achieving a harmonic explosion. In short, this increases the torque.

Less contamination

The gases expelled by injection engines are less polluting. When gasoline is supplied in adequate proportions , the gases are more refined and controlled. That's where the typical expression of "it's rich in gasoline" comes from. If the reader has the opportunity to see a carburetion car, the odors of the exhaust sometimes go somewhat loaded and that is exactly the principle by which said comment is governed.

Improves engine starting and warming

Last but not least, the injection engines manage to increase the engine temperature first thanks to the correct fuel supply. Carburetion engines, when distributing large amounts of gasoline from the start time, do not get a quick start , because they do not cover all surfaces well from the beginning and, in addition, the idle is very unstable . And when an engine is going to jerk, it will take a long time to reach its proper operating temperature.

What injection systems are on the market


1. Location of the injectors

Basically, there are two ways to place the injectors , which are the most used:

Direct injection

This system directly injects the fuel into the combustion chamber. Generally, these injectors are located in the part closest to the engine block, in the final area of ​​the intake manifolds. In this way it enters directly into the chamber of the block and it is there, where the gasoline is mixed with the air. Today, it is the most used method.

Indirect injection

This system locates the injectors (usually not more than two) in the intake manifold itself. It is important not to confuse it with the carburetion system that, although it is also housed in the intake, does not incorporate any injectors. Therefore, the injector acts in direct contact with the air and enters the block as a mixture. This type of system is not used much today, although it is incorporated by low displacement engines such as the Peugeot 108 .

2. Number of injectors

This section is closely related to the location of injectors, but shows some difference.

Single point injection

Single point injection refers to systems that use a single injector . Obviously, it is always located in the intake manifold, because it cannot inject directly into the chamber, because one injector would be needed for each cylinder. In short, it is an indirect injection system like the one just explained.

Multipoint injection

In this case, multipoint injection has as many injectors as cylinders . The big difference is that the fuel injection can be both direct and indirect. Being able to be located in the final part of the intake manifold, so that the flow goes directly to the engine chamber, or placed in the intake manifolds in a nearby area, where it mixes with the air before entering the inner zone Where are the cylinders? This system is incorporated by most medium and high-end vehicles. This is the most popular direct injection option.

3. Depending on the times they inject

In this section, we re-segment the injectors, but in this case according to the number of times they supply the fuel. So the fuel injection systems are the following:

Continuous injection

As the name implies, the fuel supply is done without pauses. Only the flow is regulated, but the injection is constant. That is, even if the engine is idling, a small dose of fuel is injected.

Intermittent injection

This system is fully electronic. It works based on the orders of the switchboard. The injectors work intermittently but, unlike continuous injection, it can stop supplying in case the engine does not require it. It is the most used system and, in turn, is divided into three types:

1. Sequential

The sequential intermittent injection, injects fuel to each cylinder separately , through an exhaustive control by the control unit, thus appealing to pure efficiency.

2. Semi-sequential

Like the sequential injection, the semi-sequential follows the same principle, but in this case it is done two by two . That is, it is a four-cylinder engine, it supplies the fuel first to cylinders one and two, followed by an injection in cylinders three and four (combinations can be varied).

3. Simultaneous

The latter intermittent system is used in the most powerful engines as a general rule. Using the advantages of the intermittent system, in this case, the injection is carried out on all the cylinders at the same time . They do not separate, but when the switchboard gives the order that the engine needs fuel, they simply spread the flow through all the cylinders.

4. Injection mechanisms

Mechanical injection system

The mechanical injection system, appeared in 1932 for aviation engines , but did not reach the vehicles until 1945 . A system that lacks electronics just like the carburetor. The injectors work by means of the pressure submitted by a dispenser , a kind of distributor that distributes the gasoline by the injectors that distribute the gasoline simultaneously, determined by the flowmeter.

Nowadays it is not usually used, since it is not as efficient as an electronic system.

Electronic injection systems

The first electronic injection system was commercialized in 1967 , with Bosch D-Jetroninc . Over the years, this launch was the culmination of injection systems. They have continued to develop until they achieve the purest efficiency. Unlike KE-Jetronic systems , a hybrid between a mechanical and electrical system, it takes full advantage of technology to properly distribute fuel at the right time. That is why today's systems are based on this system.