The properties and capabilities of the types of car engines

 The properties and capabilities of the types of car engines

 

Clarifying the properties and capabilities of the types of engines we have in our cars, the following information may be highlighted:

• Direct / full injection engines: As their name suggests, with this configuration, fuel is injected directly into the engine with no waiting time as in conventional engines with a throttle valve. There is an injector installed in the engine through which the fuel is injected into the combustion chamber. The air enters by itself through the suction valve and then the fuel is injected followed by compression and other functions. The main advantage of this system is the increased efficiency (the air to fuel ratio may exceed 40:1) and operation at high pressures (up to 15,000 PSI i.e. approximately 100,000 kN/m²).
• Port injection engines: - In port injection engines, which are engines with a throttle valve, the air-fuel mixture enters the combustion chamber. Before entering the combustion chamber, the air and fuel are mixed together in the carburetor and then forced into the combustion chamber according to the operating conditions. The main disadvantage of port injection is its low efficiency (the air to fuel ratio is about 15:1) and it usually operates in a pressure range between 30 to 60 PSI, i.e. approximately 200,000 - 400,000 kN/m².
• Turbocharger: The turbocharger is essentially based on the principle of forced induction. In the conventional engine, the exhaust gases leaving the combustion chamber enter directly into the catalytic converter and are then released to the outside. However, with the turbocharger, which consists of a turbine and a compressor in a casing, the energy of the exhaust gases leaving the combustion chamber is used. The turbocharger is installed between the exhaust section and the intake section of the engine.

What the turbocharger actually does is to harness the energy of the exhaust gases through the intake in order to spin the turbine. As the turbine spins, it also spins the compressor. As the compressor rotates, it begins to compress the air entering the inlet manifold. The advantage of air compression is that it allows the engine to compress more air into a cylinder, and more air means more fuel can be added. This way more power is produced by each ignition in each cylinder. A turbocharged engine produces more power overall than the same engine that does not have the turbocharging process. This can significantly improve the power-to-weight ratio of the engine.

This raises the legitimate question: Why are only full/direct injection engines potentially turbocharged, while this is not the case for port-injected engines? The answer can be found in the explanatory description of the engines above.

Indeed, assuming that a port injection engine is turbocharged, the main problem that will arise is mechanical knocking or pre-ignition. If the compressed air is mixed with fuel and then the mixture is recompressed, then the compression ratio automatically increases above the higher rated compression and eventually this will result in pre-ignition of the fuel.

In the full/direct injection engine, there is no connection between the air and the injected fuel before entering the combustion chamber. So we can compress the air without worrying about mechanical knocking. The compressed air will enter the combustion chamber and at the same time atomized fuel will be sprayed into it. The rest of the process has already been explained above.