BMC TwinAir air filter BMC is one of the world's leading makers of air filters for vehicles, suitable both for road use and for racing at the highest level. BMC filters are designed to allow better flow than the original part, and in some cases their pressure drop is less than half that of an original paper filter. The filters therefore provide better flow together with better filtration, and thus better protection for the engine. The filters are supplied pre-oiled and are ready to use straight away. They are designed with a maximum filter area, with an inlet both in the centre of the cone and on the outside of the filter, and they are suitable for all car and motorcycle applications and can be used together with a mass air flow sensor. BMC air filters are made from a cotton material that allows good permeability, while the combination of several oiled cotton layers stops contaminants and dirt from 7 microns upwards. Synthetic filters normally stop contaminants from 80 microns upwards. With today's technology there is no better filter system available. The red rubber has been developed specifically to resist heat, impact and vibration. All BMC filters are washable. Cleaning fluid and oil suited specifically to this purpose are available. Choosing a filter: - The dimensions of each filter are as shown in the drawing and the specification table. - The rubber connection of the filter is fitted onto a pipe or flange with the same or a similar outside diameter as the internal diameter of the filter. - Choose a filter with the highest possible air flow that still allows correct installation*. Air flows are shown in the diagram and in the specification table. * Most engines perform best with the lowest possible restriction on the intake side. Choose a filter with the highest possible air flow that can also be fed the coldest possible air. The routing of pipes and hoses from the air filter to the engine is very important. Use as few sharp bends as possible to achieve a low pressure drop and an even air flow to the intake or turbo inlet. A wide range of aluminium pipes and silicone hoses is available for building this.