The FC3S is designed with a very restrictive air intake system.
Even when replacing the stock, panel-type air filter with a freer flowing
unit (i.e. K&N drop-in), only a very small amount of power can be
freed. The restriction is not with the air filter itself but with
the stock air box.
To eliminate the restrictive, stock air intake design, you can switch
over to a cone-type air filter. For 1986-1988 FC3S you need a cone
filter adapter mounted to the front of the stock air flow meter; we, at
FC3S Pro, offer our own airflow meter adapter that is cast aluminum unit
that has a 3" O.D. inlet to fit all universal cone filters that is
typically sized with a 3" I.D. outlet. For 1989-1991
FC3S, no adapter is needed - the sliding-cone air flow meter can directly
use any cone-type air-filter can clamp down to it's 2.5" OD inlet.
One word of warning about using the cone-style air filter: caution
must be exercised to keep hot air produced by engine heat from entering
the intake to a minimum. The air filter ends up sitting in a very
hot engine bay. The FC3s does not lend itself well to a "cold-air
induction" system well - it is not easy to plumb a big enough opening
into the front of the engine bay without cutting heavily into the car itself.
Questions? Comments? Send mail to: