Performance air filters offer freer airflow than the standard paper element, allowing higher peak power output on engines that have been built up elsewhere. They use a media (cotton, foam or gauze) that traps contaminants while imposing a lower restriction than paper. Most types are re-oilable rather than disposable: cleaned and re-oiled at service intervals, they offer significantly longer service life than paper elements.
Filter Types
Cotton-gauze elements (K&N-style) trap contaminants in oiled cotton fibres, with the oil maintaining a sticky surface that catches particles. Foam elements use an open-cell foam media, again typically oiled. Both designs offer freer airflow than paper, with the cotton-gauze type generally giving the best filtration efficiency for a given flow rate.
Fitment Options
Performance filters can be fitted within the original V8 air filter housing as a direct element replacement, or as individual cone filters mounted directly on each carburettor inlet. The individual-cone approach offers the lowest possible airflow restriction but exposes the carburettors to engine-bay temperatures and direct ingestion of warm engine bay air, which can offset the airflow gain. For a balanced compromise, retaining the original housing with a performance element is usually the best route on a road car.
Service
Re-oilable filters require periodic cleaning and re-oiling. Specialist cleaner and oil products are available, and the maintenance interval depends on operating conditions. A neglected performance filter that has been allowed to dry out passes contaminants into the engine and is worse than a clean paper element.
MGOC Spares
MGOC Spares supplies performance air filter elements, individual carburettor filters, cleaning kits and oil for the MGB GT V8.