GDI engines: pros and cons of GDI engines, what they are


To improve the efficiency of powertrains, manufacturers have developed new fuel injection systems. One of the most innovative is the gdi injection. What is it, what are its advantages and are there any disadvantages?

What is auto GDI injection system

This abbreviation is worn by motors of some companies, for example, KIA or Mitsubishi... Other brands call the system 4D (for Japanese cars Toyota), the famous Ford Ecoboost with its incredibly low consumption, FSI - for representatives concern WAG.

The car, on the engine of which one of these labels will be installed, will be equipped with direct injection. This technology is available to gasoline units, because diesel has a direct supply of fuel to the cylinders by default. It won't work on another principle.

GDI engines: pros and cons of GDI engines, what they are

The direct injection engine will have fuel injectors that are installed in the same way as the spark plugs in the cylinder head. Like a diesel engine, gdi systems are equipped with high-pressure fuel pumps, which allow to overcome the compression force in the cylinder (gasoline in this case is supplied to the already compressed air, in the middle of the compression stroke or during air intake).

The device and principle of operation of the GDI system

Although the principle of operation of systems from different manufacturers remains the same, they differ from each other. The main differences are in the pressure that the fuel pump creates, the location of key elements and their shape.

Design features of GDI engines

GDI engines: pros and cons of GDI engines, what they are

The engine with direct fuel supply will be equipped with a system, the device of which will include the following elements:

  • High-pressure fuel pump (injection pump). Gasoline should not only enter the chamber, but it should be sprayed into it. For this reason, its pressure must be high;
  • An additional booster pump, thanks to which fuel is supplied to the fuel pump reservoir;
  • A sensor that records the force of the pressure generated by the electric pump;
  • A nozzle capable of spraying gasoline under high pressure. Its design includes a special spray that forms the required torch shape, which is formed as a result of fuel combustion. Also, this part provides high-quality mixture formation directly in the chamber itself;
  • The pistons in such a motor will have a special shape, which depends on the type of torch. Each manufacturer develops its own design;
  • The intake manifold ports are also specially designed. It creates a vortex that directs the mixture to the electrode area spark plug;
  • High pressure sensor. It is installed in the fuel rail. This element helps the control unit to control different modes of operation of the power plant;
  • System pressure regulator. More details about its structure and principle of operation are described here.

Operating modes of the direct injection system

The gdi motors can operate in three different modes:

GDI engines: pros and cons of GDI engines, what they are
  1. Economy mode - fuel intake when the piston performs a compression stroke. In this case, the combustible material is depleted. At the intake stroke, the chamber is filled with air, the valve closes, the volume is compressed, and at the end of the process, gasoline is sprayed under pressure. Due to the formed vortex and the shape of the piston crown, the BTC mixes well. The torch itself turns out to be as compact as possible. The advantage of this scheme is that the fuel does not fall on the cylinder walls, which reduces the thermal load. This process is activated when the crankshaft rotates at low revs.
  2. High-speed mode - gasoline injection in this process will occur when air is supplied to the cylinder. The combustion of such a mixture will be in the form of a conical torch.
  3. Sharp acceleration. Gasoline is injected in two stages - partly at the intake, partly at compression. The first process will lead to the formation of a lean mixture. When the BTC finishes compressing, the rest of the portion is injected. The result of this mode is the elimination of possible detonation, which may appear when the unit is very hot.

Differences (varieties) of GDI engines. Car brands where GDI is used

It is not hard to predict that other leading car manufacturers will be developing a system that works according to the GDI scheme. The reason for this is the tightening of environmental standards, tough competition from electric transport (most motorists tend to give preference to those cars that consume the minimum amount of fuel).

GDI engines: pros and cons of GDI engines, what they are

It is difficult to create a complete list of car brands in which such a motor can be found. It is much easier to say which brands have not yet decided to reconfigure their production lines for the manufacture of this type of internal combustion engine. Most of the latest generation machines are likely to be equipped with these units, as they show sufficient economy along with an increase in efficiency.

Old cars definitely cannot be equipped with this system, because the electronic control unit must have special software. All processes occurring during the distribution of fuel to the cylinders are electronically controlled based on data from a variety of sensors.

Features of system operation

Any innovative development will be more demanding on the quality of consumables, since the electronics immediately respond to the slightest changes in the operation of the motor. This is related to the mandatory requirement to use only high-quality gasoline. Which brand should be used in a particular case will be indicated by the manufacturer.

GDI engines: pros and cons of GDI engines, what they are

Most often, the fuel should not have an octane number lower than 95. More information on how to check gasoline for compliance with the brand can be found in separate review... Moreover, you cannot take ordinary gasoline and increase this indicator with the help of additives.


The motor will immediately react to this with some kind of breakdown. The only exception will be materials that are recommended by the car manufacturer. The most common failure of a GDI internal combustion engine is an injector failure.

Another requirement of the creators of units in this category is high-quality oil. These guidelines are also mentioned in the user guide. Read about how to choose the right lubricant for your iron horse. here.

Pros and cons of use

By reducing the process of fuel supply and the formation of the mixture, the engine receives a decent increase in power (in comparison with other analogs, this figure can increase up to 15 percent). The main goal of manufacturers of such units is to reduce environmental pollution (most often not from worries about the atmosphere, but because of the requirements of environmental standards).

This is achieved by reducing the amount of fuel entering the chamber. The positive effect associated with improving the environmental friendliness of transport is a reduction in fueling costs. In some cases, consumption is reduced by a quarter.

GDI engines: pros and cons of GDI engines, what they are

As for the negative aspects, the main disadvantage of such a motor is its cost. Moreover, the car owner will have to pay a decent amount not only to become the owner of such a unit. The driver will have to spend decent money on engine maintenance.

Other disadvantages of gdi engines include:

  • Mandatory presence of a catalyst (why is it needed, read here). In urban conditions, the engine often goes into economy mode, which is why the exhaust gases must be neutralized. For this reason, it is not possible to install a flame arrester or blende instead of the catalyst (the machine will definitely not be able to fit into the framework of eco-standards);
  • To service the internal combustion engine, you will need to purchase a higher quality, and at the same time more expensive, oil. The fuel for the engine must also be of higher quality. Most often, the manufacturer indicates gasoline, the octane number of which corresponds to 101. For many countries, this is a real wonder;
  • The most problematic elements of the unit (nozzles) are non-separable, which is why you need to buy expensive parts if you cannot clean them;
  • You need to replace the air filter more often than usual.

Despite decent flaws, these engines give encouraging predictions that manufacturers will be able to create a unit in which the maximum of shortcomings will be eliminated.

Preventing malfunctions of GDI motors

If a motorist has decided to buy a car with a gdi system under the hood, then a simple prevention of malfunctions will help to extend the working life of the "heart muscle" of the car.

Since the efficiency of the gasoline supply system directly depends on the cleanliness of the nozzles, the first thing you need to pay attention to is periodic cleaning of the nozzles. Some manufacturers recommend using a special gasoline additive for this.

GDI engines: pros and cons of GDI engines, what they are

One option is Liqui Moly LIR. The substance improves the lubricity of the fuel by preventing clogging of the nozzles. The manufacturer of the product indicates that the additive works at high temperatures, removes carbon deposits and the formation of tar deposits.

Should you buy cars with GDI engines?

Naturally, the newest development, the more difficult it will be to maintain and capricious. As for the GDI engines, they demonstrate excellent gasoline economy (this cannot but please the ordinary motorist), but they do not lose power.

GDI engines: pros and cons of GDI engines, what they are

Despite these obvious advantages, power units have low reliability due to the very delicate operation of the fuel rail. They are picky about the cleanliness of the fuel. Even if a gas station has established itself as a quality service, its supplier may change, which is why no car owner is protected from counterfeiting.

Before deciding to buy such a vehicle, you need to decide for yourself whether you are ready to compromise in order to save fuel or not. But if there is a material base, then the advantage of such cars is clear.

In conclusion, a short video review of one instance of a direct injection internal combustion engine:

What's wrong with direct injection from the Japanese? We disassemble the Mitsubishi 1.8 GDI (4G93) engine.


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