Motorsport Plumbing Systems: System Overview
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System Overview
12.29
| 00:00 | - In this section of the course, we're going to be covering the fundamental knowledge needed when it comes to tackling any sort of automotive plumbing job. |
| 00:07 | And because there are different mediums being transported and contained within a vehicle, that all have their own specific requirements, we'll be breaking this knowledge down into each system. |
| 00:18 | We'll start the process by discussing each of the key systems of the vehicle that involves plumbing. |
| 00:24 | The principles on how the system functions, the parts involved and the plumbing connecting them. |
| 00:30 | Before we dive in though, let's get a few definitions out of the way to ensure that we're all on the same page. |
| 00:36 | First when we say plumbing, we're referring to any form of enclosure, be it a pipe, tank, fitting, manifold or similar that conveys fluid. |
| 00:46 | Plumbing can also be used to describe the act of working on the plumbing system. |
| 00:51 | Next, the system is defined as a set of interconnected parts that work together to achieve a certain function and there's various plumbing systems in a vehicle that convey various fluids. |
| 01:03 | Lastly, a common misconception is that the term fluid refers only to liquids. |
| 01:09 | But put simply, a fluid is really just a substance that has no fixed shape and yields easily to pressure, meaning it will flow and in an automotive context, this could be a gas or a liquid. |
| 01:22 | That being said, the point of this section is to make sure that you have a solid understanding of all the plumbing systems in a vehicle so we'll make sure to cover anything that's critical to this. |
| 01:33 | With that all cleared up, we'll start with the plumbing system that could be considered as the first in order of the combustion engine cycle, the intake and charge air plumbing. |
| 01:43 | Air is a mixture of different gases but most importantly to us, air contains oxygen and the engine requires oxygen as part of the combustion process. |
| 01:53 | You've likely heard before that internal combustion engines are essentially an air pump. |
| 01:58 | Basically the more oxygen that flows into the engine, the more potential we have to make power, all other things considered. |
| 02:06 | This is best described as the volumetric efficiency of the engine which tells us how completely the cylinder is filled on the intake stroke and it's influenced by a lot of factors, such as camshaft design, exhaust efficiency and relevant to this module, intake system restrictions. |
| 02:25 | Essentially, we want to increase the density of the intake air so more oxygen is packed into the cylinder on each intake stroke. |
| 02:34 | Although the humidity is mostly weather dependent, the colder and higher pressure we can make our intake air, the greater the density it'll have and the more power we can therefore make. |
| 02:44 | Let's quickly look at what's involved in the system and then come back to this. |
| 02:48 | For naturally aspirated engines, things are fairly simple. |
| 02:52 | In the most common arrangement, there's an air filter which may or may not be enclosed in an air box. |
| 02:59 | This filtered air is then conveyed through some piping to a throttle body where it enters the intake manifold and can flow into the engine. |
| 03:07 | In this case, the intake air plumbing really only consists of the piping from the filter to the throttle body. |
| 03:14 | The plenum and manifold could also be considered as plumbing but the design of these components is outside the scope of this course. |
| 03:22 | There are some alternative arrangements though and we'll discuss these in a moment but first, we need to cover what's important for performance. |
| 03:30 | The main objective is keeping the intake air temperatures as low as possible and not restricting the flow, causing a pressure drop from atmospheric pressure to the air pressure that's in the manifold. |
| 03:42 | Remembering that lower temperature and higher pressure mean higher air density and more power potential. |
| 03:50 | While using less restrictive air filters, larger throttle bodies and more efficient plenums, are common paths for reducing intake restrictions, in terms of plumbing, it really comes down to the size and shape to not disrupt airflow. |
| 04:04 | Put simply, we want faster and smoother unrestricted flow into the intake manifold which is one of the reasons we often see trumpets or velocity stacks used on the intake. |
| 04:15 | The other reason we'll discuss shortly. |
| 04:17 | In some arrangements, we'll also see the use of one throttle body per cylinder, commonly referred to as individual throttle bodies or ITBs. |
| 04:27 | Whenever a turbocharger or supercharger is being used in any of the various configurations, the result is artificially increasing the pressure of the intake air, creating a high differential between the cylinder vacuum and the charge air in the manifold so more air is crammed into the cylinder. |
| 04:47 | The positive pressure above atmospheric pressure is referred to as boost and the compressed air being supplied to the engine is often referred to as charge air. |
| 04:57 | The plumbing of these forced induction systems does vary depending on what type of compressor is being used. |
| 05:04 | With a roots or screw type supercharger, the throttle body is positioned before the compressor so for the purposes of our plumbing work, it's very similar to an NA setup in that it's still just the piping from the filter to the throttle body, the charge air from the compressor is generally sent straight into the intake manifold towards the intake ports. |
| 05:26 | For turbochargers and centrifugal superchargers on the other hand, the intake plumbing is a bit different. |
| 05:34 | As with nearly all cars, there's still a filter but this is then plumbed to the compressor inlet, from here there's more plumbing to the throttle body. |
| 05:42 | Between the compressor and the throttle body, in the vast majority of cases, there's some other components and while they aren't imperative to the function of the system, they do provide some big advantages. |
| 05:55 | One being the intercooler which is a heat exchanger used to cool the intake charge. |
| 06:00 | This is needed because while pressurising the intake air, superchargers and especially turbochargers causes a substantial increase in air temperature, the intercooler helps to cool the intake charge after being pressurised and before entering the engine. |
| 06:16 | The other component we'll often see between the compressor and the throttle body is a pressure relief valve, often referred to as a blow off valve, bypass valve or recirculation valve. |
| 06:27 | The purpose is the same regardless of what we're calling it. |
| 06:31 | Venting boost pressure from the system after the throttle is closed. |
| 06:35 | In some cases, the outlet of this valve is vented to atmosphere or it can be plumbed back into the intake before the turbo or supercharger inlet. |
| 06:45 | Sometimes the valve is even built into the compressor housing of the turbo. |
| 06:50 | The way in which these should be ordered, whether it's intercooler then valve or vice versa is commonly argued and you'll see effective factory and aftermarket examples of both. |
| 07:01 | What's more important in this case is the execution of the setup rather than the order of the components and as such we tend to recommend installing the valve wherever is most convenient. |
| 07:13 | While a wastegate is part of the exhaust plumbing side of the cylinder head, which we aren't covering in this course, there are various pneumatic lines plumbed to the wastegate from the intake side, so it's worth discussing it for completeness sake. |
| 07:27 | If you'd like to learn about the function of wastegates and how they control boost pressure in turbocharged applications, I recommend checking out our dedicated boost control course which you'll find a link to under this module. |
| 07:41 | In any case, there will be plumbing between the turbo compressor housing or intake manifold to the ports of the boost control solenoid and wastegate. |
| 07:50 | There can also be extra plumbing attached to the intake system that's not related to its function. |
| 07:56 | A common example of this would be the vacuum source for a brake booster in the form of a simple rubber hose connected to the intake manifold between the throttle body and the cylinder head. |
| 08:07 | Another example could be a breather from the valve cover to the intake before the throttle body. |
| 08:13 | Which is generally also a rubber hose to act as a breather that vents the crank case pressure. |
| 08:19 | More often than not in motorsport applications though, both of these are removed as the brake booster is usually deleted in favour of a motorsport style pedal box and the valve cover breather is routed to a catch can rather than the intake. |
| 08:34 | It's very common, especially in more factory configurations to have an airflow sensor in the intake, usually just after the filter or air box and this needs to be considered in the plumbing if it's going to be retained. |
| 08:48 | This is because the size of the mass airflow or MAF sensor housing is critical to the calibration of the sensor. |
| 08:55 | If not, it'll more than likely be replaced by a MAP or manifold absolute pressure sensor which in some cases can also involve some additional plumbing if not connected directly to the manifold. |
| 09:08 | Finally, a MAP referenced fuel pressure regulator will have vacuum line plumbed to the intake manifold. |
| 09:14 | We'll discuss these more soon in our fuel system modules but this is as simple as a small rubber hose on pneumatic line connected to the ports on the parts. |
| 09:24 | With a clear view of the system architecture for forced induction applications, we need to cover the considerations in terms of the plumbing. |
| 09:33 | First, minimising the pressure drop between the compressor and the intake manifold is still very important. |
| 09:40 | To do this, we want to prevent restrictions between the compressor and the manifold and obviously the plumbing also needs to be completely sealed to avoid boost leaks. |
| 09:51 | It's also important than the intake from the filter to the compressor is as unrestrictive as possible, otherwise the turbo will need to work harder to achieve the target boost pressure which will result in more heat generation. |
| 10:05 | Although there's a common misconception that the length and size and therefore volume of the inlet plumbing increases lag or decreases boost response in any practical application, the effect here is much less than most would expect. |
| 10:20 | The main downside of longer intake and charge air piping is the extra weight. |
| 10:25 | Aside from this, it could be argued that there's more potential for restrictions, leaks or heat soak but this is on a case by case basis and not a problem if the system has been designed, fabricated and maintained properly. |
| 10:40 | Keeping intake and charge air temperatures as low as possible remains one of the primary objectives. |
| 10:47 | On the topic of temperature, we'll also need to consider the integrity of the plumbing as all the components will need to withstand the high engine bay temperatures experienced in motorsport as well as the high internal pressures that come with forced induction. |
| 11:02 | For now, let's leave the discussion of heat management there as we'll be diving into this in more detail in its own module later in the course. |
| 11:11 | We've covered a lot in our first system overview so let's look back over the key points. |
| 11:16 | In the most simple naturally aspirated application, the plumbing system we'll most likely be designing ourselves is from the air inlet at the filter or air box to the throttle body. |
| 11:28 | From there, the air usually flows straight into the intake manifold which although there's some advantages to modifying or fabricating a manifold, we won't be delving any further into this as it's a big subject that's outside the scope of this course. |
| 11:44 | Forced induction systems essentially those utilising turbos or centrifugal superchargers on the other hand, are more complicated and feature more components with the general layout being the filter or air box, plumbed to the compressor which is then plumbed to an intercooler and blow off or bypass valve and then through to the throttle body. |
| 12:06 | In either application, our primary concerns are the same. |
| 12:10 | Keeping the intake temperatures as low as possible and the intake plumbing as unrestrictive as possible, all in the interest of volumetric efficiency and therefore performance, while also considering air velocity for low end performance as well as drivability. |
