Quote:
Originally Posted by The Radium King
well, i too personally feel the high rpm gains associated with modifying the intake for higher flow outweigh the low rpm losses that result from any de-tuning that occurs, which is why i am currently running a 997 plenum, cayman throttle body and 85mm BMC DIA airbox.
i have located my maf closer to the throttle body (like in a 996) as well. unfortunately, this has resulted in the need for a bend in the ducting immediately before the maf. i think i will have to rework my intake geometry in general (remove the engine compartment insulation so that i have room to mount my airbox a little lower and get things straight); fact is, the oem intake geometry is pretty good as-is.
turbulance and maf reading? unsure. oem porsche airboxes do put a screen before the maf, but it is not a full honeycomb as is available aftermarket. i am currently re-using the maf housing from my old airbox so had to cut-off the screen, but am thinking i need to add something as i'm getting a bumpity idle.
otherwise, i am currently using flex duct for my intake tubing. aftermarket vendors get all up in arms about flex duct and try to sell you $300 work of pre-formed plastic pipe under the auspices that flow is less turbulent, but i'm always brought back to the stories of the russian mig fighters and the fall of communism. here was a plane that was relatively on par with anything the west could produce, but when we finally got a chance to look at one we found that it was ill-made and replete with exposed rivets, bumps, lumps etc. all this served to create a layer of turbulent airflow which was much more frictionless than anything you could design. similarly, flex tubing should create a small layer of turbulence that will enhance laminar flow within.
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I would think flex tubing would constitute a "rough pipe" which will translate to flow losses. An open surface with dimples is a much different animal and has been found to enhance laminar flow (non compressible regime).... like aircraft skins; golf balls..
You would have to run the numbers and test to know whether the flex duct is giving significant losses but generally you can expect pipe friction losses
I can concur with the feeling that bottom end is slipping away for a more explosive top end above 4k as more intake opening changes are made. It's worth it for making passes on the track but not so much for pulling out of an underground parking garage with a cold engine