With the promise of unleashing more power from their engines, some people install a "performance" low-restriction air filter. What they may not realize, however, is the trouble this could cause.

Modifying the engine's intake system to fit a performance filter may void the new-vehicle warranty, say advisors in this field. It could also lead to engine damage from water entering the intake, and may not even gain much power because, depending on design and placement, additional engine heat can actually reduce power compared to a stock filter.

"The main purpose of an air filter is to keep harmful particles out of the engine while promoting proper air flow," explains Jay Buckley, an ASE certified master mechanic and technical training manager for Fram Group. Dust, smog, rain plus even dead leaves and insects, enter a car's intake tracts during normal driving. It's amazing how even a tiny particle of dirt can score a cylinder wall, ultimately shortening the life of an engine.

"A good engine air filter must balance dirt trapping efficiency with low restriction," Buckley continued. "Quite simply, some performance air filters compromise dirt-trapping efficiency in order to maximize airflow."

He recommends a quality air filter, like Fram Extra Guard with 99 per cent full life efficiency - that is the ability to remove dirt the first time it goes through the filter. It is engineered to fit precisely and provide the manufacturer-specified level of engine protection. Not only that, but replacing an old, clogged air filter with a new one can actually increase horsepower and acceleration. This is the very thing that the "performance" filters claim, says Buckley, but without any loss of engine protection.

Be aware of the risks involved with "performance" air filters, he adds, and protect your vehicle's engine by replacing the air filter every 20,000 kilometres.

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