Gasoline Direct Injection (GDI)- Why Are These Engines Relevant?

BS6 emission regulations were a hugely positive step forward in the direction of a cleaner environment. Not only India, but every country in the world is moving towards stricter emission laws. This is because everyone is becoming environmentally conscious, with global warming causing various disasters around the world frequently. The time to act is now before it’s too late.

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Continuing this principle, the automobile industry had to come up with various new technologies to make sure that the vehicles produce as little pollution as possible. Especially after implementing BS6 norms, many car makers simply had to do away with the diesel engines. This is because it was very expensive to upgrade a diesel engine to meet the emission requirements. With the hybrids and electric vehicles coming in, many companies have discontinued diesel powertrains from their lineups globally. They think it is better to invest in something that is future-oriented, like Hybridisation and Electrification.

GDI Turbo Petrol Direct Injection Engine

One of the ways to meet the emission requirements is to adopt an efficient fuel injection system. Since fuel affects all the aspects of an internal combustion engine, for example, power, torque, emissions, heat management, combustion timing, knock, etc. The basic principle of an internal combustion engine is to mix the fuel with air to enable combustion of this mixture to produce power. This is what essentially propels the cars forward. The key is to have control over the amount of fuel injected into the engine as well as the mass of air that comes into the cylinder. This ratio is what determines how much emissions will a vehicle emit or how much power a vehicle will make.

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Let us consider the two main types of fuel-injection systems used in automobiles today.

Port Fuel Injection System

Port Fuel Injection refers to the system, where the fuel is injected into the intake manifold of the engine. The fuel mixes with air thoroughly because there is a lot of time. During the intake and compression stroke of the piston, the fuel is mixed very well with the air. The quality of combustion determines the amount of power and emission that the engine will produce. Fuel injectors are used in this system, which sprays the fuel in the intake manifold.

Advantages and Disadvantages of Port Fuel Injection

  • There is precise control of the amount of air and fuel so that the desired air-fuel mixture ratio is achieved. This is essential in getting the desired results from the engine. For example, if the power output is your priority, you can spray a bit more fuel (rich mixture with more fuel and less air). If, however, efficiency is your main concern, then you can make a lean air-fuel mixture (more air than fuel).
  • Because the fuel is sprayed in before the intake valve, it can help keep the valve clean. This happens as a result of the additives present in the fuel.
  • Because of a lot of time to mix air-fuel mixture the combustion is clean with less pollution.
  • The cost and maintenance are easy and inexpensive in comparison to the direct fuel injection system.
  • One major disadvantage is the deposition of some fuel on the walls of the intake manifold. This can cause inaccuracies in achieving desired air-fuel ratios.

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Direct Fuel injection System

The most efficient system used in modern engines is the direct fuel injection system. We are talking here particularly about petrol engines because diesel engines have been using this technique for a long time. As the name implies, the fuel is injected directly into the combustion cylinder. The time to mix this fuel with air is very little. Therefore, the injectors are capable of spraying the fuel at pressures up to 350 bar! This is necessary because, at such high pressures, the size of the fuel particles is fine and thin, which enables them to mix with air very quickly. Also, the spray radius is wide.

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Advantages and Disadvantages of Direct Fuel Injection

  • The amount of fuel entering the cylinder can be controlled completely and even with more precision than the port injection.
  • This increases the efficiency of engines because of finely condensed fuel particles.
  • Because the fuel is directly sprayed into the cylinder, it has a cooling effect. Therefore, the compression ratio can be increased without the fear of knock, which is typical in a petrol engine.
  • Disadvantages include an expensive setup. This is because the high-pressure operation requires components that are stable at high pressures. These are generally more expensive.
  • The cleaning process, as in the case of port fuel injection, is not there. Hence, carbon deposits can be found on the valves.

Gasoline Direct Injection Engines In India

Lately, many carmakers have adopted Gasoline Direct Injection Engines with turbocharging. This includes Hyundai and Kia Motors, with their GDi moniker. It is found in i20, Grand i10 Nios, Venue, Sonet. These engines make more power and torque as compared to their naturally aspirated counterparts. Volkswagen has the famous TSI engine, which it uses in the Polo and the Vento. Even the CBU T-Roc launched earlier, had a bigger, 150hp 1.5-litre turbo petrol with direct injection technology.

Apart from these companies, Mahindra has developed an entire family of modern engines equipped with gasoline direct injection technology. Mahindra showcased these engines during the Auto Expo 2020. There are three engine options in the line up: 1.2-litre 3 Cyl, 1.5-litre 4 Cyl and 2.0-litre 4 Cyl, direct injection turbo petrol.

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This clearly points in the direction the industry is heading. Turbo petrol engines with gasoline direct injection is the way forward. It makes sure that the engines comply with the emission norms, provide better efficiency than before and also enhances performance by producing more power and torque output. We are bound to see even more such engines going forward.

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