The main types of injection systems used in cars

Have you ever thought about the massive feats of engineering that go on underneath your bonnet? Fuel injection systems have come a long way since the carburetor, to provide your car with both more power and greater fuel efficiency.

Whether it’s a direct or port system, electronic or mechanical, there’s a lot of different setups out there. But how do they work? And why would you choose a car with one over another? Read on to learn all about these essential parts of your car’s engine!

What are fuel injectors?

For your car’s fuel to power your engine, it first needs to be mixed with oxygen.

The role of fuel injectors in this process is to spray fuel into your car’s engine under pressure, where it is then mixed with oxygen in the cylinders, ignited with a spark, and used to power your engine.

There are several different types of injectors, so we’ll go over each below.

Mechanical fuel injection

Before electronic fuel injection was a thing, there was mechanical fuel injection. Originally designed with aircraft in mind, it works best with the throttle fully open and isn’t really efficient by today’s standards. Unlike electronic injection, the fuel injectors are opened by the pressure of the fuel when you put your foot down, and don’t have the benefit of sensors and a microprocessor to automatically calculate this for you.

However, it’s still used today in drag racing and sprint cars, and looks pretty cool when you see the massive injectors sticking up out of the hood. Unfortunately, it takes a lot of maintenance and isn’t as precise as electronic fuel injection, so it’s not something that’s used much outside of the racetrack.

Electronic fuel injection

The newest form of fuel injection, making its way into the production lines in the mid 70s, electronic fuel injection is controlled by a computer system called the Electronic Control Unit (ECU). This tells the injectors when to open and how long for by measuring the engine temperature, throttle position, and speed. This results in a more efficient ride, with lower emissions—and is still widely used in cars today.

Direct injection

Direct injection is a type of electronic fuel injection, where the fuel injector sprays fuel directly into the combustion cylinder where it mixes with oxygen and combusts. Because of this, no fuel is wasted, resulting in better fuel economy and less emissions.

Throttle body injection

Introduced in the mid-80s as an early form of electronic fuel injection, throttle body injection, also known as single point injection, has one or two injectors located at the throttle body, which acts as a valve restricting air into the engine. When you press the accelerator, it opens the valve mechanically to let more air in, increasing the revs and power. The fuel is sprayed into the throttle body via the injectors.

Which type of injection system is best?

All these different systems have their pros and cons regarding fuel efficiency, economy, maintenance costs, availability of parts and so on. Let’s take a look at a few side-by-side to get a better idea of what’s right for you.

Direct injection vs port injection?

Port injection is the older of the two systems, where fuel is injected into the intake valves and mixed with air before going into the cylinder for combustion.

With direct fuel injection, the fuel is injected directly into the cylinder.

Both have their pros and cons. Direct injection has better fuel economy due to no fuel being lost in the intake valves, as well as providing more power. It also lowers the chance of knocking at higher speeds, as it lowers the temperature in the cylinder.

Port injection however, provides a cleaning effect on the intake valves, which reduces the amount of carbon buildup, which can be a problem with direct injection. They’re also cheaper as they don’t need to withstand the high pressures of direct injectors.

As they can mechanically benefit each other and provide combined advantages, these systems work better together.

Carburetor vs fuel injection?

Carburetors are an outdated form of fuel injection that hasn’t been used in new cars since the 1990s. They have their pros and cons, the main pro being their durability and ease of maintenance, but the reason they’ve been surpassed by modern fuel injection systems is because they’re pretty inefficient by comparison, and produce higher emissions.

They work on the same basic principles as modern fuel injectors—to mix fuel and air—but they aren’t as precise. As electronic fuel injection systems atomize the fuel and use oxygen sensors to calibrate the needs of the engine more precisely, less fuel is wasted leading to a car that’s cheaper to run with lower emissions.

Common rail vs direct injection?

Common rail is in fact a type of direct injection technology, used in modern diesel engines. So it’s not really a matter of whether one is better than the other, but how common rail helps in direct injection.

The rail is connected to the fuel injectors, accumulating fuel under pressure before sending it to the injectors to be sprayed directly into the cylinders. It surpassed the older indirect injection systems, which injected the fuel into a chamber before releasing it into the cylinder.

The advantages of common rail are lower emissions, more power and performance, and less noise and vibration. Its disadvantages include its cost, higher maintenance requirements, and more expensive parts.

If you have any questions or would like to book in for a service, call mycar to speak with one of our trusted mechanics today.