I read a few threads about removing the powerduct (on the intake box), did it, didn't notice any down-low tq loss and it sounded bad-*** above 4k RPM.

So now my question - has anybody taken off the powerduct and enlarged the air-flow opening by, say, grinding away a little bit of the plastic on the sides, so the opening is larger?

 

Not sure it's really necessary. The native design seems to work pretty well. I think a Z tube and perhaps a less restrictive filter might be plenty. It's a straight shot and a good design.
I'm running my car with the stock airbox in lieu of my Stillen airbox at the moment. No question it sounds different, though I'm not how much power difference there is.
The one thing I did notice is a bit less pinging/detonation when using the stock airbox.

 

If changing the airbox results in pinging/detonation, then there's something very wrong with your a/f or the gas you put in it.


Anyways, I was just wondering if grinding the opening to make it even larger made it louder, or once you take off the duct, that's pretty much the tone you're going to get regardless of if you open it up more or not.

 

Cuttting out the lower portion of the Power Duct cover will result in a deeper induction sound. Removing the Power Duct all together will result in even more induction sound. The trade off, especially with the spacer, is reduced tip-in throttle response. It's not significant, but I can notice it. Above 4000rpms, the throttle response is a bit better with the modified/removed cover. It's up to you which you value more, great all around throttle response or sweet induction noise. I wish I could have both, but for now I'm back to the stock Power Duct cover.

 

Righteo, but what would happen if, after removing the powerduct, you also ground down the opening on the air box even more to make the hole even larger......even deeper induction sound, or waste of time?

 

Why bother cutting up your airbox. Just remove the over radiator snorkel. The induction noise with the Power Duct and snorkerl removed is EXACTLY like the POP Charger/Stillen....and it's free. The gains are probably the same too (0hp )

 

perhaps my ears just aren't as sensitive, but i didn't notice any more induction noise by removing the snorkel. but removing the powerduct made a huge difference - and you're right, it was free!

 

same here - no noticeable difference removing the lower resonator (catch can)

 

It won't sound exactly like the stillen or JWT but should have a bit more sound. I do believe that the other give you a couple hp but are more for sound.

 

So I am guessing nobody here has tried cutting up their air box even further to enlarge the opening, hehe. Hmmmm, choices choices.

 

anybody with real knowledge about fluid dynamics know why that little reservoir beneath the stock air box is even there?

 

Noise suppression. It's not a Hemholtz resonator. I've run around with the resonator plugged and open and I notice absolutely no difference in tip-in and WOT acceleration. When I put my modified Powerduct cover on or remove the Power Duct all together, I notice laggy tip-in throttle acceleration and slightly boggy part throttle shifts. The motor also looses that surge of acceleration upon each gear shift. I've run with and without the Power Duct cover at the track and there is no difference in ET/MPH.

 

that's really good insight but do you know how it alters noise levels by ther simply being a chamber that isn't really in the path of the "noise maker" i.e. the noise of rushing air that is absorbed. does the sounds reflect into that chamber due to design of the chamber or do you think perhaps it could be for another reason such as to catch higher weight material that may get sucked in through the "power duct" and so that they have a place to fall and are no longer within the path of the air flow of the stock airbox.

my guess is that i's a place for things to fall (liquids, bugs, etc) so that tehy don't sit stagnant in the stock air box and eventually get it all nasty and dirty. anyone tried dumping out their little chamber box or does it have a hole in the bottom of it too (if it does then that would further develop my theory)

 

I used to work in a molecular biology lab and every time we aspirated something ther was a chmber of sorts to "catch" the fallen pieces of small particulates that might get clogged into our filter so we could keep sucking just air and therefore pull only that out.