Motorsport Plumbing Systems: Routing & Heat Management
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Routing & Heat Management
07.05
| 00:00 | - Speed is usually the key objective in most forms of motorsport but unfortunately the main product of kinetic energy in mechanical systems is thermal energy. |
| 00:10 | Essentially, more speed, most often means more heat. |
| 00:14 | With heat transfer mechanisms like convection, conduction and radiation, the temperature of all components in the vehicle will be increased. |
| 00:23 | Managing this heat generation is undoubtedly one of the most challenging factors in motorsport when it comes to maintaining performance, reliability and safety. |
| 00:32 | For each plumbing system we cover, we'll discuss the effect of this heat and how it is managed, along with routing considerations for the plumbing as this is critical to heat management and also has a significant effect on performance. |
| 00:47 | We just mentioned 3 heat transfer mechanisms but let's clarify these to better understand how heat is transferred through components in an automotive context. |
| 00:57 | Then we'll discuss how this has an impact on our intake plumbing. |
| 01:01 | Starting with conduction, this is the transfer of heat through a part or between parts that are in physical contact. |
| 01:09 | Since the intake plumbing is connected to the other components by the engine itself that's hotter than it is, the plumbing will get hotter as a result. |
| 01:18 | The more direct the connection and the hotter the other parts are, the hotter the intake parts will get but this also depends on the thermal mass and conductivity of the materials. |
| 01:29 | Radiation on the other hand is heat transferred through space. |
| 01:33 | This is when the parts aren't touching. |
| 01:36 | For the intake, this means the plumbing gets hotter from the radiant heat of other hot components in the engine bay like the engine and exhaust manifolds. |
| 01:44 | The more exposure to these components and the hotter they are, the more heat that will be transferred. |
| 01:51 | Lastly and most crucially where our intake air is concerned, is convection. |
| 01:55 | This is the heat transfer from one place to another due to the movement of fluid. |
| 02:01 | In terms of the intake plumbing system, this is essentially the air getting hotter from flowing through the plumbing and components that are hotter than it is. |
| 02:10 | The hotter the plumbing, the hotter the intake air flowing through it will get. |
| 02:14 | Convection also takes place outside the plumbing with heat transfer between the components and the engine bay air flowing around it. |
| 02:23 | This all contributes to heat soak which is a commonly used by very broad term in motorsport. |
| 02:29 | Essentially meaning that hot components in the engine bay transfer heat to other components, raising the temperature of those components. |
| 02:37 | All three heat transfer mechanisms need to be considered and minimised in the interest of lower intake air temperatures. |
| 02:46 | As well as the reliability, service life and functionality of the parts in the system. |
| 02:51 | We discussed in the previous module that the different plumbing materials have different levels of thermal conductivity and without getting too deep into the physics of heat transfer, essentially that means that they also absorb heat energy at different rates. |
| 03:05 | But since the mass of the plumbing is so small relative to the surface area, the difference in these properties becomes irrelevant and the plumbing will take on enough heat to reach approximately the same maximum operating temperature regardless of the material. |
| 03:21 | The convective heat transfer to the intake air is dependent on the plumbing surface area, the temperature of the surface and the properties of the air itself and how fast it's flowing. |
| 03:33 | Not the material properties of the plumbing. |
| 03:36 | This means that the same heat will be transferred to the air regardless of the plumbing material. |
| 03:42 | The intake manifold and other larger components are a different story due to their mass but they're not of concern to us in this instance anyway. |
| 03:50 | At the end of the day, we want to minimise the conductive and radiative transfer of heat to the intake plumbing, reducing the plumbing temperature and therefore reducing the heat transfer via convection to the intake air as it travels through the plumbing. |
| 04:05 | It's also beneficial to lower the air temperature in the engine bay so the convective heat transfer removes temperature from the intake components rather than heating them further. |
| 04:15 | So how do we do this? First of all, it shouldn't be overlooked that for forced induction applications, in which the intake air temperatures are heated by the compressor, this is exactly the purpose of intercooling and this usually results in the most transfer from the system. |
| 04:33 | Aside from this, and more relevant for NA engines, the simplest and most effective way of reducing intake plumbing temperatures is through looking at the routing of the plumbing. |
| 04:43 | Basically, keeping it out of the way of any high temperature heat sources. |
| 04:48 | For example, not running the intake right next to the exhaust or engine block and especially making sure the inlet for the air to the filter or air box is coming from a high pressure fresh air source in the front bumper of the vehicle rather than pulling it from the hot engine bay air. |
| 05:05 | Having the plumbing routed ideally can also save weight and remove restrictions in the intake air flow but in some cases, packaging constraints can make the ideal routing impractical or impossible. |
| 05:18 | In these cases, one of the next best steps should be to lower the air temperatures in the engine bay and use convection to cool the intake plumbing. |
| 05:26 | This is done by ducting fresh air into the engine bay, ideally directing it to flow over the intake plumbing and then releasing the heated air out of the engine bay through vents. |
| 05:38 | The other option is to shield the radiant heat from getting to the intake plumbing using heat shields, typically made from stainless steel, aluminium or highly reflective wraps to reduce the absorption of radiant heat energy or insulation around the intake plumbing, further protecting it from heat sources. |
| 05:57 | Alternatively, we can try to prevent the radiant heat from escaping from the heat source components in the first place. |
| 06:04 | This is commonly achieved using things like turbo blankets and exhaust wrap or shielding made from aluminium, Inconel or other alloys, all of which work to reduce the heat radiated from the hot components, like exhaust manifolds and turbochargers. |
| 06:18 | With that covered, let's now review the key takeaways around heat management found in this module before moving on. |
| 06:26 | Heat can be transferred to our intake air via 3 different mechanisms, conduction, radiation and convection. |
| 06:33 | We want to minimise these to keep our intake air as cool as possible and this can be done by routing the system to avoid heat sources, lowering the engine bay temperature by ducting fresh air in and venting hot air out, insulating the intake plumbing and shielding from radiant heat sources like the turbo and exhaust manifold and of course for a forced induction application, one of the most effective ways of achieving lower intake temperatures is by increasing the efficiency of our intercooling. |
