Performance filters.. Foam is best
One of the simplest, cheapest, and easiest performance improvements you can make to your car is the engine air-filter, yet it is one that is commonly overlooked. It is a very simple upgrade from the OEM paper filter to a foam filter and can be home installed on your driveway without the need for any special tools in a few minutes.
The primary role of the engine air-filter is to prevent your engine from being damaged with dirt, dust, sand, and other contaminants that might get drawn into the engine intake. Most OEM air-filters are constructed from pleated paper, manufacturers use them as pleating increases the surface area and it is, a slightly cheaper option than the alternatives. Paper filters are disposal and are normally replaced when your car is serviced, as they tend to clog up between services.
The problem with paper as an air-filter material is, that it does a great job of blocking larger contaminants from getting into the engine, but it can also be restricting especially as the filter gradually clogs up. This has a negative effect on performance. In the simplest terms, more air, more fuel, equals a bigger bang and more performance.
The pleating on paper air-filters as I said, is designed to increase surface area which is desirable as this reduces pressure drop and allows a freer airflow. As particles begin to build up between the pleat pack recesses however, it blocks up the potential flow areas reducing performance. Pleated filters are good at arresting large particles and can initially be more free flowing, but they can allow smaller particles through which could cause increased engine wear. An alternative to the OEM paper filter is a foam filter.
Several years ago, we partnered with well-known air-filter manufacturer Pipercross to create the Swallows Racing range of performance panel filters for the modern Jaguar range. They are a great first step in improving performance and making the engine breath more easily. The foam is layered in a format that catches different size particles at different levels. This layering, and the thickness of the foam, is what allows our SR filters to catch dirt, but not get blocked up in the same way an OEM paper or even cotton gauze filters can. The oil that is impregnated within the foam further assists in catching and spreading the dirt throughout, stopping build up in one area. This means that from service to service, the filter retains full breathing potential and isn’t slowed down by a build-up of dirt which paper filters commonly suffer from. (see diagrams below)
Paper Filter
Cotton Gauze Filter
Foam Filter
There are further advantages with foam filters, a better breathing filter and more air flow can also mean you see better fuel economy as well as performance from your car. Foam filters can be washed at every yearly service or 10000 miles, meaning that you buy once and aren’t paying for a filter every time you have your car serviced. Because the filter can be washed, it makes it an eco-friendlier option too.
You may have been told by your dealer or garage that foam filters impregnated with oil can ruin your MAF (Mass Air Flow) sensor. It is a common misconception that the oil from foam filters can ruin you MAF. Our partners Pipercross sell thousands upon thousands of filters every year and have next to no mention of MAF problems, we certainly haven’t experienced any in our time working them. This myth more than likely comes from a few vehicle service outlets trying to add cost to service bills by insisting on changing the filter with a paper one. Pipercross control the level of oil impregnated into our foam filters, adding just enough to allow the filter to work but not so much that it ever leaves the filter.
In racing applications and some of our more extreme performance upgrades we decide to completely do away with the air-box and panel filter and modify the intake so we can fit a cone filter. A word caution if you considering this type of upgrade, the air-box is designed and located to prevent heat-soak. Cold air is denser than warm air, if we get hot air going into the engine then it will restrict performance. We have even seen badly prepared race cars fitted with cone filters that are clearly drawing hot air, location of the filter is key to gaining performance.
So why use a performance cone filter? Well, the air-box is always going to add a restriction, if we can do away with it, we can get air into the engine more easily, but we still need to filter out any contamination. The cone filter allows us to do this, secondly the shape of the filter allows us to increase the filter surface area, normally greater than surface area of a panel filter. A greater surface area means we can get more oxygen into the engine, and we are sucking in air all the way around the cone, not just from one restricted source. The disadvantages of cone filters are, they take longer to fit, they are more expensive, and you need to be able to locate them correctly to avoid heat-soak. If you are going to be mainly doing town driving and stuck in traffic then a cone filter isn’t going to work well for you, they need constant airflow, if you are driving on the motorway, open roads and on the track then you’ll see a benefit from this style of filter. Generally, we would fit cone filters as part of a larger package of engine upgrades.
Our range of SR Jaguar panel filters is available from the Swallows Racing online shop
