Air Cleaner Housing: Description and Operation

2425 Air Filter Housing With Sound Openings







To avoid a possible intake of warm air from the engine compartment even under critical engine operating conditions (e.g. high ambient air temperature), the sound openings on the underside of the air filter housing have been modified. By using openings with a large surface area with inserted, almost airtight fabric, the intake of warm air from the engine compartment is nearly completely prevented while the intake sound typical for Porsche is retained.


911 Carrera S (997) Air Filter Housing







The construction of the air filter of the 911 Carrera S basically corresponds to that of the 911 Carrera (996) model year 2004. The redesign of the scoop and the upper part of the air cleaner with the integrated
"PORSCHE 3.8" logo as well as the rerouting of the hoses and lines are essential elements for the upgrading of the engine compartment with an attractive look.

2425 911 Carrera S (997) Switchable Resonance Reservoir

The air filter of the 3.8 liter engine differs from that of the 3.6 liter engine through an active on-demand resonance reservoir integrated in the upper part of the air filter.







Undesired noises can be insulated by adjusting the volume of the reservoir according to engine speed, whereby sound in the passenger compartment is optimized. One of the goals in adjusting the passenger compartment sound has been to reduce background noise in the higher frequency range and to greater emphasis, the sporty, load-related exhaust and intake noises between 300 and 600 Hz. Opening and closing the resonance reservoir produces an improvement in the intake sound of the 3.8 liter engine, particularly in combination with the specific intake system of the 3.8 liter engine.

This reservoir is activated via a vacuum-controlled flap as a function of engine speed and using temperature compensation. The flap operates in the temperature range between 32° F. (0° C.) and 90° F. (30° C.), opening between approx. 4,600 and 4,800 rpm and closing between approx. 6,000 and 6,250 rpm.