986 Forum - The Community for Porsche Boxster & Cayman Owners - View Single Post

The Radium King · 01-13-2011, 09:22 AM

i'll modify my bs slightly. the 987 series have a second resonance flapper on the plenum; the 986 does not. the ipd product does away with this flapper on the 987; it's a non-issue on the 986. so, perhaps no issue with low rpm tuning to add an ipd plenum (or equivalent) to a 986?

here is the thread that i referred to earlier; scroll down a little over 1/2 way to see a quick simulation of airflow through a stock plenum - see how the sharp inside bend reduces airflow by over 50%:

linky

perhaps someone could confirm, however, that max airflow is not required? ie, that the engine recieves sufficient air as designed. i ask as i read somewhere that the 987 has smaller manifold intakes than the 986, so revising airflow pre-manifold on the 986 (with smaller engine) may not be worthwhile?

01-13-2011, 09:22 AM	#47
The Radium King Registered User Join Date: Apr 2010 Location: Canada Posts: 3,122	i'll modify my bs slightly. the 987 series have a second resonance flapper on the plenum; the 986 does not. the ipd product does away with this flapper on the 987; it's a non-issue on the 986. so, perhaps no issue with low rpm tuning to add an ipd plenum (or equivalent) to a 986? here is the thread that i referred to earlier; scroll down a little over 1/2 way to see a quick simulation of airflow through a stock plenum - see how the sharp inside bend reduces airflow by over 50%: linky perhaps someone could confirm, however, that max airflow is not required? ie, that the engine recieves sufficient air as designed. i ask as i read somewhere that the 987 has smaller manifold intakes than the 986, so revising airflow pre-manifold on the 986 (with smaller engine) may not be worthwhile?