Motorsport Plumbing Systems: System Overview
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System Overview
10.51
| 00:00 | - Unlike the intake air plumbing we covered in the previous section of the course, the next few systems we'll discuss are more relateable to what most people would be familiar with when it comes to plumbing, in that the fluid they convey is in liquid form. |
| 00:14 | In this module we'll be covering the coolant plumbing system, how it functions, the components involved and what we need to consider for performance in motorsport. |
| 00:24 | Let's start with a definition, the word coolant, which in our case is a fluid used to reduce or regulate the temperature of our engine. |
| 00:32 | We're specifically talking about coolant as a liquid that runs through the engine and coolant plumbing system. |
| 00:39 | Sticking with our assumption of a base level of understanding, it should go without saying that as an internal combustion engine runs, it generates heat, simply as a result of the combustion process. |
| 00:50 | If there is no effort to cool the engine, the temperature will continue to increase until something gives up. |
| 00:56 | In the best case, the engine will stop running, in the worst case and more commonly, there'll be serious irreversible damage to some parts of the engine. |
| 01:05 | The coolant for engines is primarily water and glycol based. |
| 01:10 | Water is used since it has a high heat capacity and good heat transfer characteristics and the glycol is used as an antifreeze to lower the freezing point and also raise the boiling point. |
| 01:23 | Different coolant formulas have varying freezing and boiling points. |
| 01:27 | Coolants can also contain additives such as corrosion inhibitors, for example to prevent corrosion inside the engine block and plumbing. |
| 01:36 | What's important to understand where the plumbing is concerned is that as the coolant gets hot and boils, the pressure increases and it expands. |
| 01:44 | The radiator cap and overflow tank help to relieve this build up but we'll touch more on this soon. |
| 01:50 | The risk of the coolant freezing on the other hand depends on your local temperatures and is really more of a concern for street cars living outdoors. |
| 01:59 | Regardless, it's still something that needs to be accounted for. |
| 02:02 | If the coolant freezes, it'll also expand but it obviously can't flow so this can damage components or force the freeze plugs out of the block. |
| 02:11 | The difference here for motorsport is that glycol based coolants are extremely slippery if they leak out onto the track in the event of a crash. |
| 02:19 | For this reason, these coolants aren't allowed at many motorsport facilities and the alternative is to use deionised water. |
| 02:26 | There are some vehicles or engines more specifically that are exceptions to this where the coolant and coolant plumbing system aren't used to cool the engine. |
| 02:35 | These engines are air cooled which was common in old VWs and the more performance orientated Porsches. |
| 02:42 | But due to the lack of cooling efficiency it's not something we see on modern vehicles, especially in motorsport. |
| 02:49 | In modern vehicles and motorsport applications, there are other water or coolant plumbing systems separate to the main system. |
| 02:57 | For example, a cool suit to help keep the driver cool or water to air intercoolers, water meth injection and intercooler sprayers that all work to lower the intake air temperatures. |
| 03:09 | These systems aren't the focus of this module but a lot of the same techniques and ideas can naturally be applied. |
| 03:16 | With that covered, let's get back to the engine's coolant plumbing and cover how the coolant flows through the system in the most common configuration which can be referred to as a bottom up coolant system, based on the direction of the coolant flow through the engine. |
| 03:29 | There are some variations with different vehicles but the fundamentals are the same so we'll discuss a basic common configuration first and then discuss alternatives. |
| 03:39 | Starting at the water pump as the name suggests, this pumps the water through the plumbing system and the engine, circulating the coolant through the system. |
| 03:48 | Water pumps can generally be split into two groups, those mechanically driven by the engine, usually via an accessory belt which is by far the most common method, or alternatively an electric water pump which is often used in motorsport applications. |
| 04:04 | This is because in motorsport, where we're often seeing higher rev limits and more time spent at higher RPM, mechanical water pumps can cause cavitation of the coolant flow. |
| 04:14 | Something we want to avoid as it diminishes the cooling performance and can damage parts. |
| 04:20 | The coolant from the pump is then forced through the engine where it flows through the passages in the block, cylinder head and sometimes the intake manifold. |
| 04:29 | Heat is transferred to the coolant from the engine through convection, raising the temperature of the coolant but lowering the temperature of the engine. |
| 04:37 | With a bottom up coolant system, the coolant is plumbed upward through the system, following the natural flow of warmer fluid to rise above cooler fluid. |
| 04:46 | What's referred to as thermal siphoning. |
| 04:49 | An electric water pump will have plumbing to the engine whereas a mechanical water pump will usually be built into the engine's coolant passages. |
| 04:57 | After the coolant has passed through the engine, it then enters the thermostat. |
| 05:01 | This is essentially a valve that regulates the flow of coolant through the radiator which we'll discuss in a moment, depending on the coolant temperature. |
| 05:11 | Simply put, when the coolant temperature is too low, it stops the flow through the radiator, in some cases diverting the coolant flow back to the inlet for the engine or the water pump. |
| 05:22 | When the temperature is high, it allows flow through the radiator. |
| 05:26 | The purpose of the thermostat is therefore to keep the engine in its optimum temperature range. |
| 05:33 | Moving on, assuming the coolant temperature is high enough, the thermostat allows flow through the radiator via some more plumbing. |
| 05:39 | The radiator is a heat exchanger; as the hot coolant flows inside, ambient air flows over the radiator, reducing the temperature of the coolant and increasing the temperature of the air via convective heat transfer. |
| 05:53 | Radiator fans are also most often used to help with airflow through the radiator. |
| 05:58 | Especially at lower vehicle speeds. |
| 06:01 | Contrary to popular belief, the benefit of radiator fans is minimal above about 30 mph or 50 kph and as such, they're often removed on dedicated racecars to aid in weight savings and reduce complexity. |
| 06:17 | Looking back at our bottom up coolant system, the coolant enters the top of the radiator and flows downwards through it as the temperature decreases. |
| 06:25 | While it is being pumped in this direction, it also follows the same idea as the engine around thermal siphoning with the cooler fluid naturally moving downwards regardless. |
| 06:35 | The heated air from the radiator is eventually released into the airstream as the vehicle moves through it. |
| 06:42 | The radiator is also attached to an overflow tank which functions as a reservoir. |
| 06:47 | The flow between the radiator and this tank is controlled by the radiator cap which acts as a valve similar to the thermostat while also sealing the system. |
| 06:56 | When the heat of the coolant in the system increases, so does the pressure and it expands. |
| 07:02 | To prevent the system from bursting, the radiator cap allows the coolant to pass through to the overflow tank. |
| 07:09 | Alternatively if there isn't enough coolant in the system, this will result in a vacuum in which case the radiator cap will allow coolant to be drawn in from the overflow tank which is functioning as a reservoir. |
| 07:21 | The result is a regulation of the level and pressure of the coolant in the system as well as raising the temperature that the system can operate at. |
| 07:30 | This is because increasing the pressure of the coolant, increases the boiling point. |
| 07:34 | Different radiator caps can change the pressure at which the flow occurs and therefore the maximum pressure of the system and the resulting boiling point. |
| 07:44 | After exiting the radiator with the temperature reduced, the coolant flows through more plumbing and back to the engine or water pump to start the process again and that's the core of our system in its most simple form. |
| 07:56 | Finally, before we move on, let's quickly discuss some potential sub systems that can be found within some cooling systems. |
| 08:03 | For example, the heater for a production street car. |
| 08:06 | In this case, the hot coolant from the engine can be directed by the heater controls to flow through another heat exchanger called the heater core and work with a fan to heat the air inside the cabin of the vehicle. |
| 08:19 | This is usually removed in a dedicated motorsport vehicle to save weight, reduce failure points and cut down on unnecessary complexity. |
| 08:28 | There could also be additional plumbing in a forced induction application that uses a turbo. |
| 08:34 | This is required due to the exhaust gas temperature being transferred into the turbo core and then the oil which we'll be covering in a coming module. |
| 08:42 | Generally this will be in the form of coolant plumbing from a port in the engine cylinder head or block to the turbo core and then from the turbo back to the block or plumbing somewhere before the radiator. |
| 08:55 | It's not uncommon to use some kind of coolant distribution block to help with this, especially on engines that were originally naturally-aspirated from the factory. |
| 09:04 | In most cases, the coolant inlet to the turbocharger core will be below the outlet and this comes back to the same idea of thermal siphoning. |
| 09:13 | However, there will usually be a recommendation on this angle by the turbo supplier so as not to impede on the adjacent oil flow. |
| 09:21 | There are also examples of coolant being used to warm components like the throttle body or intake manifold. |
| 09:28 | We see this commonly in older factory configurations to help with drivability in idle when the engine warms up in extremely cold climates. |
| 09:37 | Regardless of the variations, the fundamental workings of the system are much the same so let's recap what we've covered in this module before moving on. |
| 09:46 | Coolant is used to regulate the temperature of the engine and other components to keep them in their optimal operating range. |
| 09:53 | The system comprises of a water pump that forces the coolant through the engine passageways and around the rest of the system. |
| 10:01 | A thermostat to help regulate the temperature which can be removed in some instances, and a radiator that acts as a heat exchanger to reduce the temperature of the coolant before it returns to the engine where it'll all be heated again. |
| 10:14 | The radiator works along with an extra tank that depending on the temperature and coolant level and therefore pressure in the system, can function as an overflow or reservoir. |
| 10:26 | The flow to and from which can be controlled by the radiator cap. |
| 10:29 | With forced induction, it's common to have coolant running to the turbo or in factory configurations, there will likely be a heater system involved and possibly even coolant flowing through the throttle body and intake manifold. |
| 10:41 | All these components are connected via some form of piping and this will be the plumbing of interest moving forward. |
