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sidebar - i was snooping around and found a site that showed the 997.2 plenum(hard info to find, as the online parts diagrams for the dfi 09+ cars are not readily available).
what is interesting to note is that the 997.2 plenum has a resonance flap (the 997.1, they one we've been discussing to-date, does not).
to track the evolution of these things, my understanding is as follows:
reason - the resonance flaps stay closed at low rpm to facilitate intake tuning. at high rpm they open to maximise airflow. they tend to activate around the same time as the cams turn over. note that the presence of the flap, even when open, can restrict max airflow, so the flap is a compromise between low rpm and max hp.
986/996/997 - resonance flap on the resonance tube, but none on the plenum.
987/cayman - flap added to the plenum
997.2 - flap added to the plenum
so, for some reason, porsche decided late in the game to add this technology to the 911 series. i presume that they initiallywanted max mid-range for their 'turny' cars, and max hp for their 'straight line' cars. i guess they eventually decided that the 3.8 had engough hp and needed more low rpm grunt.
SO, we've got to ask ourselves - more top end or more low end? if i can squeeze a 997.1 plenum in there, i should be able to squeeze a cayman plenum in there (which has the resonance flap). i'll have to check, but i should be able to tee off the line that controls the other resonance flap to drive this one. then it's just a matter of rigging the aos connection.
perhaps both and a back-to-back comaprision?!?!?
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