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Question about Intake Silencer


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Originally Posted by bmc

ahhhh, see your point, sorry it took so long. This may be my mistake. The car does become louder, I was assuming without the intake silencer the turbo spool and air "sucking" sound would be louder. Instead what I heard was a deep growl (which I thought was the exhuast note) when on the gas.


Still doesn't make sense to me why this growl went away when I plugged the hole and didn't put the silencer back. It was the same with my BMW. After installing the CAI, the car had a deeper rumble/growl to it. Never really understood why it did this.. I attributed it to more air flow on the intake. I guess I've beat a dead issue long enough now, so I'll leave it alone.


think of it as some buffeting noise. Like driving on the highway with the windows down, you get a loud buffeting pressure vibration in the cabin. If you have a sun roof, and you pop it open, the noise goes away, since there is a way to equalize the pressure.


With the intake, and having a second opening after the OEM intake scoop, it can result in some buffeting when the throttle is open and the turbo spooling, thus "sucking" in cold air from both the OEM scoop and the hole where the silencer was. These are at different frequencies and when both open, they resonate within the engine bay. I have a CAI on my MINI, it is open not only to the outside air intake, but to the engine bay as well, it creates a throatier noise at WOT. This is a result of less buffering of the air as it enters the throttle body. Granted, our throttle bodies on the turbo charged are WAY after the air box, but still, the vibration caries out through the intercooler, back through the turbo and into the airbox. As was discussed earlier...like an exhaust muffler but in reverse. I also like to think of it as a sub woofer, and at certain frequencies, ie-rpms, and pressure of WOT, the louder it sounds. The 2 openings create more room for resonance in the engine bay (or side of the engine bay as Jedi likes to clarify). With the hole taped, the final sound only comes out by the OEM scoop, up by the headlight...and that scoop in itself has a "silencing" property. Take any air box apart, and run a car with out it, and you will have the same result...loud intake. Simple as that. More filter, more plastic, more distance from the throttle body and various intake components, the less noise you will have, take all that away, and it will be loud.


did I ramble? Forgive me, finishing a 24 hours shift at work, and it is nearly 0445am here ;)



This monday I went to remove the intake silencer and discoverd it shouldn't be done. reason 1 is your losing the ram air effect of the air coming from under the hood and reason #2 is when you leave the hole unplugged you are just asking to suck water into the engine. If you do plug the hole, you lose the cool sound. I plugged the hole with a plastic tube end and works fine, it just doesn't make the sounds any more.
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i have removed my silencer and left the hole open with no ill effects.


as fas as concerns go ---


getting water into the intake: you would need to be in at least a foot and a half of standing water before it would be at the level of the opening... and by that point i think you've got bigger issues at hand.


losing 'ram air' effect: I'm very skeptical of this for 2 reasons

1) the turbo is actively sucking in air to maintain a certain PSI. I have noticed NO drop in PSI at all... so it would seem that the turbo is having no problem getting enough air to pull in

2) dyno results show no loss in power with silencer removed




If you're going to block the hole -- you might as well not remove your silencer because it will negate any sound increase you would have gotten with it removed.



just my thoughts at least....

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