Engines breathe. There, we said it. Although, if by breathe, we mean to take in gas and exhaust the gas, then yes, but certainly not as humans do. Like we spoke about in our recent article covering how carburettors work, engines need oxygen to mix with fuel, like petrol or diesel to create combustion, ultimately creating power. So, where does this air come from and where does it go afterwards? All will be revealed in this blog, as we take a look at the workings of intake and exhaust. 

How Does Intake & Exhaust Work?

The Importance of Intake

Much like humans, if an engine is starved of oxygen, it dies. Well, not dies, but ceases to be able to perform its function of turning fuel and oxygen into power. The combustion triangle only works if all three things are present, removing one of those things (such as oxygen), will cause the combustion to stop.

Intake serves the function of delivering air to the engine when it needs it, working with the carburettor (where one has been fitted) to ensure that air can always be used for combustion. With engines that use fuel injectors, these are often mounted onto the intake manifold to inject fuel directly into the cylinders.

A lot of modern generators use a four-stroke engine, also known as a four-cycle engine. The engine is named four strokes for the four separate operations that occur inside the cylinder: intake, compression, combustion and exhaust. The piston, working with the intake and exhaust valves, allows these four operations to occur, creating mechanical energy.

We recently talked about carburettors and their operation within an engine. For context, a carburettor forms part of the intake system in petrol and diesel engines, acting as one piece of the puzzle when it comes to combustion. In four-stroke engines, the first stroke of intake pulls in an air and fuel mixture into the cylinder from the carburettor. During the compression stroke, the valve that allowed this mixture into the cylinder closes to keep the cylinder airtight, allowing for the combustion to occur.

What Role Does the Manifold Play?

You may have heard of the inlet or intake manifold; this is a piece of kit that serves the purpose of distributing air to all cylinders of an engine. Many inlet manifolds are built with four connecting tubes (known as runners) which pass air from the plenum (the main section of the manifold) to the cylinders. For larger V8 engines, you may either use a dual-plane manifold which is essentially two manifolds working together, or a single-plane manifold which can feed all eight cylinders at once.

In generator engines, many smaller, portable devices are powered by a single-cylinder engine, meaning the intake manifold only has to supply one cylinder with oxygen and fuel.

How Does Intake & Exhaust Work?

The Importance of Exhaust

In the same way that air comes into the engine, air must also leave the engine after combustion has occurred. Although, as we all know, this isn’t lovely clean, breathable oxygen, so some steps are necessary to clean and reduce pollutants before the air is sent back into the atmosphere.

Unfortunately, combustion within an engine is not entirely efficient, meaning that there are by-products of the combustion that must be exhausted from the system. For example, some of the fuel may be unburnt, or partially burnt, and this needs to be ejected from the cylinder before the next cycle of combustion can take place.

The exhaust system begins straight after the cylinder, with the exhaust manifold, otherwise known as the exhaust header. Much like the intake manifold takes one source of air and splits it into multiple sources, feeding each cylinder, the exhaust manifold brings the exhaust from each cylinder back into one collective pipe.

In modern car engines, the collection of pipes that forms the exhaust system serves a number of purposes, including cooling off the exhaust gases, feeding the gases through the catalytic converter and dampening the noise from the engine. Many catalytic converters require extraordinarily high temperatures to be effective (426 degrees Celsius), so they are placed as close to the engine as possible.

In generators, catalytic converters are also fitted to clean up the exhaust fumes from the engine. Because generators generally have a much smaller surface area than a car, the exhaust system is much more compact, which is often why generators can be quite noisy.

It’s not uncommon for intake and exhaust to be the root cause of a problem within a generator. Maybe your kit has been left for too long, and the carburettor has clogged up, or perhaps your exhaust system isn’t quite functioning as it should. Regardless, you can get in touch with us here at Edge Technology to book in your service or repair.

We also stock a range of brand new generators, from small and mighty suitcase generators to more substantial heavy-duty devices. Browse our range here!