What is an induction kit and what does it do?
An induction kit usually refers to the components used to replace the standard air box and cold air feed to the engine. Its main function is to improve an engine’s performance, by improving its ability to feed cold fresh air to where the car needs it most.
Are they all the same?
There are many different types of aftermarket performance air intake systems available. While the aim of all the intake systems should be the same (to increase the air flow the engine), the designs and final results can be very different.
What are they made of?
The two main components of an induction system are the airbox or heat shielding and air filter. The airbox/heat shield provides a housing for the air filter and is used to channel cool air from outside the engine bay directly to the filter. It also has the added function of isolating the air from the effects of heat generated by the engine.
An air filter is essential to ensure that air drawn into the engine is clean and free from any contaminants that could potentially be harmful. There are many different shapes and sizes of filters used, depending on the application (road car, desert rally car etc). It is common for most OEM manufacturers to use pleated paper panel filters in the induction system while aftermarket performance products tend to feature a cone or cylindrical shaped filter to increase the available surface area. The shape, size and material of the filter has an impact on the amount of air that is able to pass through it.
How do aftermarket induction kits differ to OEM intakes?
Usually they are larger, and capable of flowing more air. Production cars are made up of a series of compromises, and the filter will be sufficient for a standard car but might start to struggle to meet the demands of a tuned car. Remember, more air is required to make more power.
Why, or when, would you need to upgrade your induction kit?
In engine tuning, a method of increasing performance is to increase the fuel used in the combustion process. This increase in fuel leads to an increased requirement of air to maintain the necessary fuel air ratio. In some cases, the restriction posed by a vehicle’s standard intake system can limit the flow of air, hence the need for a performance induction kit.
How important is it to get the right type of induction kit?
There are several options when deciding what induction modification to make to a vehicle. There are three main categories: First up, a panel filter upgrade, which uses the vehicle’s existing airbox and replaces the standard pleated paper filter with high-flow filter, typically made from cotton gauze, synthetic material or foam. Next is an open induction system, which removes the standard airbox and replaces it with a filter connected to the intake pipe mounted within the engine bay. As no airbox or heat shielding is used, the incoming air can be warmer and less dense, so optimum performance may not be achieved. The use of a heat shield is often employed to segregate the filter element from the engine. The final option is closed cold air intake, where a performance airbox is designed around the optimum sized filter for the performance gain required. Housing a filter in an airbox provides a constant flow of cool air to the filter, whilst shielding the filter from the high engine temperatures.
What are the limitations of OEM intakes? Do aftermarket induction kits suffer the same fate?
Compromise. The limitations of the OEM intakes are often due to the regulations that are imposed on the car manufacturers. A lot of the restrictions in the standard airboxes are due to the need to remove noise from the induction system, which often disrupts airflow. The OEM induction systems are designed to do a specific job to a specific power output. What the designers didn’t have in mind was people like us coming along wanting to extract more power and needing to flow more air.
What other mods should you consider when uprating your induction kit?
Just like many other aspects of your car, the induction system will work at its best when the rest of the car’s breathing is optimised. Gains from an induction kit alone may be marginal (depending on how restrictive the OE item is that it replaces), but when you start further tuning with better-flowing exhausts, bigger ports (and sometimes valves), lairy cam profiles, or bigger turbos, then it becomes pretty obvious that a performance air filter will be required to flow the volume of air demanded by those other performance upgrades.
Are there any downsides to aftermarket induction kits?
When an aftermarket induction system is fitted it removes the restriction of air flowing to the engine. This means aftermarket intakes can be considerably louder than the standard one. For the majority of people this is all part of the allure of an induction kit, however some people may find this a nuisance. Also, some open induction systems, without the correct ducting to ensure a strong cold air feed, can actually end up losing power due to drawing in the hotter, less dense air from the engine bay – a phenomenon known as heat soak.
Other than ensuring you get the right one for your application, what are the most important things to look out for when buying an induction kit?
Always look for a trusted brand with experience in all forms of motorsport, as the development path taken by these large teams with big budgets, eventually ‘filters’ down to road car applications. You should also consider the purpose of what you want the car to do. Street cruiser or track day warrior? Will noise be an issue? Consider warranties too, an established company with a good reputation will be far easier to deal with should you encounter any issues. Your engine bay is a pretty harsh environment; subjected to repeated heat cycles plus the worst the weather and wet conditions can throw at it too. It’s not common, but it’s unfeasible for a component to fail in these conditions, and if it ever did, you’d want a company to help you when you need it.