Quote:
Originally Posted by jaykay
My stock 2000 S intake pipe does have a small Helmholtz chamber built into it which I lost upon installing a 74mm TB.
These acoustic devices certainly do have performance enhancing merit. I have seen them in Titanium FI exhaust systems. I would hope that in the case of the Boxster intake pipe that the design intent was a more favourable performance result rather than just a noise reduction effort.
I actually found that I attained better throttle response below 4500 rpm by re-introducing a chamber into the intake tract. I also went from a 3,25" to a 3,0" tract diameter at the same time so perhaps this was the more dominant factor. Anyway this set up seems to work well with the 74mm TB and stock airbox. I measured these effects via 100% throttle position and engine rpm vs. time. Peak HP is a whole other matter!
With the above modifications, I also found that my custom snorkel gave better response above 4K while the stock snorkel slightly improved 3-4K throttle response. Looking at what is termed the "drip tray" on the stock snorkel and the direction of airflow into the side vent, I would guess that the drip tray was actually intended as an airflow director...so I left it on. Sooo if ever I track my Boxster again think I would fit my jaykay snorkel so that I might just pull by that pesky 964 in my run group.....
...yes my air box snorkel tang holes are just about shot!
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This is making me rethink the removal of the Helmholtz chamber. I'm not sure if I'll have the room to leave it on though. You know how tight it is in there when adding the 997 Distribution T. Tomorrow I start the tear down process. Once I get the 987 air box in, knock sensors, starter replaced, 997 Distribution T and 996 76mm TB installed I'll see what I can figure out.