Techno Torque Part 2.

[The Radium King]

from what i understand, the ipd version actually disables one of the intake resonance flappers (designed to tune the intake at low rpm) the idea being to flow max air at high rpm (gets all obstructions - like resonance flappers - out of the way). as a result, the ipd plenum is acknowledged to have a low rpm torque dip (lots of dialogue at planet 9 where there are more cayman applications) presumably associated with the loss of low rpm tuning. ipd's solution to this is to use a larger throttle body which works like a sprint booster - more throttle sooner - to get you past the dip quicker.

comparing ipd (softronic make something similar) to the tt, there were some fluid analysis graphs posted in a similar thread, and my take was ...

air flowing from the throttle body hits the plenum and turns left or turns right into the two manifolds.

the stock plenum has a hard surface on the outside of this turn, and a 90 degree hard corner on the inside of the turn.

the airflow will adapt to this by cavitating on both the outside and inside of the turn, reducing cross-sectional area available for airflow into both manifolds.

the big offender is on the inside of the turn, where the turbulence on the inside of the bend dramatically constricts the airflow.

on the outside of the bend, the area of cavitation looks remarkably like the little piece of plastic pedro puts into the tt. my thinking is that the airflow will naturally do that the tt tries to do, and that there is no benefit.

the ipd product addresses the inside of the bend also, by replacing the 90 degree hard corner with a gradual, smooth curve. this will improve airflow.

given that, one would think that a muffler shop could fabricate a y-pipe with an aos bung to do exactly the same thing. as initially noted, however, some low rpm torque is lost with this approach.

[insite]

Originally Posted by The Radium King

from what i understand, the ipd version actually disables one of the intake resonance flappers (designed to tune the intake at low rpm) the idea being to flow max air at high rpm (gets all obstructions - like resonance flappers - out of the way)...............

interesting. i didn't realize they were doing that, too. this is again misguided, IMO, since the point of the resonance valve doesn't have anything to do with flow, only with NF.

i hadn't seen the flow field charts; that would be interesting. the biggest piece of data missing, IMO, are graphs of pressure vs. RPM at each intake runner. betcha dollars to donuts ANY of these items will create an imbalance. the intake really needs to be analyzed as a system.

[The Radium King]

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?

[JAAY]

Go to the dyno. Go stock, go IPD and see the difference in the power. It Is not a max HP number. It smooths out the overall curve and its real R&D must have been where we kick to high cam. No more dip in power just and increase. That is there big 25hp claim and it is there. The Softronic piece looks to be awesome! Big money and would not work on my car because it is too old. I would do it though if I had the chance. I wish I had as much knowledge as you all do on this subject but I have tried all the mentioned and the IPD has caused no problems and has fixed the dip in power when we switch to high cam. Sorry I have nothing to say about fluid dynamics or scoops or cavitation.

Anyone know how to change the oil?

[Johnny Danger]

The problem for most of you guys is that you haven't tried the new RRJ III super plenum yet. It gives you real seat of the pants power .