Most new petrol cars you see today are equipped with fuel injection systems or injector motors. These have almost wholly supplanted older carburetor motors. They are more reliable, effective, and eco-friendly. Several types of fuel injection differ in mechanism and work principles. We’ll talk about most of them here in this article.
Fuel Injection is the process of introducing fuel into an internal combustion engine. Diesel (compression-ignition) and petrol (spark-ignition) engines have their fuel injection systems, providing portion fuel injection through small nozzles under high pressure in the combustion chamber. In the beginning, manufacturers used fuel injection systems in aviation to help pilots run the engine in any plane position. The first mass-produced diesel passenger cars with fuel injection appeared in the late 1930s. Early injection systems were inefficient, so they were quickly overtaken by carburetor motors.
The carburetor is a device that mixes air and fuel in the required ratio before letting it into the combustion chamber. It is technically simple, inexpensive, easy to maintain, and most importantly, it does not require electricity. Instead, it uses the engine’s natural air suction. Before the new era of microchips and complicated automotive electronics, carburetors prevailed on the market. But starting in the 1980s, injector technology came back.
Carburetors are still in use but in simpler engines for scooters, motorboats, chainsaws, or lawn mowers. Modern injector systems are controlled electronically. They are much more accurate and can cope with strict emission standards. They help you save fuel, provide more power at lower engine speeds, and increase overall stability.
You can classify fuel injection systems according to different characteristics. These include external or internal air-fuel mixture formation, number of injection points (nozzles), and direct or indirect injection (whether the fuel goes straight to the combustion chamber or not). There are three main types used in modern cars that you need to know about:
- single-point injection
- multi-point injection
- direct injection
Single-point is the simplest and earliest injection system that replaced carburetors in the 80s. They are somewhat outdated, though. It uses only one nozzle in the throttle body, which sprays fuel to an air intake manifold shared by all cylinders. Air and fuel mix here and go to the cylinders through intake valves. This system is more precise than a carburetor and does not require significant changes in the engine. Now it is considered below eco-standards and not reliable, as the break of a single nozzle crushes the whole system.
In this system, all cylinders have separate nozzles, which inject fuel close to their intake ports. Doing this allows the car to use gas more effectively. They connect to a fuel pipeline, and they work in tandem. Different types of multi-point injections depend on the nozzle synchronization: Simultaneous, Batched, and Sequential. Simultaneous Injection is the primary option, where several nozzles work together and inject the fuel simultaneously.
It is a little better than a single-point system, as the fuel is brought closer to the valves, and it is simple and reliable. Batched-type injector nozzles work in pairs in rotation, depending on cylinder phase, saving more fuel. This system is often used as an emergency mode for sequential injection engines when the phase detectors are broken.
Sequential Injection is the most common and effective system currently in use. It saves maximum energy and improves emissions even more. This system coordinates each nozzle separately with its cylinder phase, so each nozzle sprays the fuel just when the intake valve opens.
This system is the best in class, primarily used in diesel engines. It’s much more expensive and complicated to set up in petrol cars. In Direct Injection, the fuel goes directly to the cylinders past the valves, allowing more control over the engine and measuring out the fuel with better precision. Direct Injection systems need to be engineered better as everything inside the combustion chamber must be coordinated with accuracy, from the timing and length of sparking to air-fuel mixture flow to work done by the valves and nozzles.
Bringing all this together in one cylinder is also a challenge: the combustion chamber must be bigger. This means the system is best in powerful cars with larger engines.
Over the past hundred years, fuel injection systems have evolved considerably. From carburetors to single-point injectors to today’s state-of-the-art, direct fuel injection, manufacturers have worked to build ever more efficient and eco-friendly fuel injection solutions for their vehicles.
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