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Discussion Starter #1
Greetings!

Removed the air intake pipe from my 1.5dci Note this morning and couldn’t help but wonder, what are the three holes underneath for? Any ideas? I’ll attach a pic:
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Also, if anyone would like to enlighten me on the random box coming off it too I’d be intrigued...

Thanks!
 

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The box is an expansion chamber, called a Helmholz resonator, it's purpose is to control back pressure waves in the inlet and produce better gas flow, as well as making the inlet a bit quieter.

The holes are likely to let water out rather than run it straight into the engine, I suppose they could allow a bit of warm air in to prevent the airflow sensor freezing, but it seems a bit haphazard for that.
 

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Discussion Starter #3
Thanks for your reply, I’d never heard of Helmholtz resonance before, just been reading up on it...
Found this great little quote that made me smile as I thought of all the ‘drill your airbox’ videos out there: “Years ago, before airboxes were designed as resonant systems, it used to be popular to cut additional holes in the air box to allow more air flow for high rpm. This is no longer a good idea. Modern air boxes can flow much more air than the engine will ever use.”

Thanks again!
 
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