# 2011 Jetta 2.5 air filter engine cover



## afawal (Oct 18, 2005)

Hey all, 

I was replacing my engine air filter this weekend and noticed something a little odd. There are a series of small holes in the engine cover portion leading to the air filter. See image below: 










Is this normal? My car is a 2011 Jetta, 2.5. First time I change the air filter, only 22k miles on the engine. From what I remember, the DIY air filter write-up picture of the engine cover didn't have these holes. 

Thanks!


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## truwagen (Jun 14, 2007)

Apparently normal: http://forums.vwvortex.com/showthread.php?5155213-Jetta-air-filter-location 
http://forums.vwvortex.com/showthread.php?2489995#post27536262


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## driftme (Apr 12, 2008)

theyre supposedly to make sure the engine is ventilated with that big ass cover on it.


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## thygreyt (Jun 7, 2009)

the thing about the oem plastics os that they absorb a LOT of heat... 

so when the air comes in, its super hot, regardless of outside air temp. 

on top of their fucntionality, putting aluminum parts on the engine helps a lot because it helps to dissipate heat and cool the engine with the ram air coming.


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## truwagen (Jun 14, 2007)

thygreyt said:


> the thing about the oem plastics os that they absorb a LOT of heat...
> 
> so when the air comes in, its super hot, regardless of outside air temp.
> 
> on top of their fucntionality, putting aluminum parts on the engine helps a lot because it helps to dissipate heat and cool the engine with the ram air coming.


 are you serious? the thermal conductivity of aluminum is orders of magnitude higher than that of plastics...


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## itskohler (Jan 7, 2011)

Ya, the thermal conductivity of plastic is like .03 or something and aluminum is around 250. Making aluminum about 8000 times more efficient at transferring heat. This is why pots and pans have plastic handles, not aluminum.


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## Dronks (Jun 7, 2011)

Holes are there to drain water that comes up the intake track.


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## driftme (Apr 12, 2008)

those holes aren't big enough to drain water thats not under pressure. the surface tension of the water won't allow it. 

yes im a physicist. kohler and i are colleagues =]


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## itskohler (Jan 7, 2011)

:thumbup:


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## Cherb32 (Jun 18, 2006)

Get a CAI/short ram and get rid of it.


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## Dronks (Jun 7, 2011)

driftme said:


> those holes aren't big enough to drain water thats not under pressure. the surface tension of the water won't allow it.


 
:thumbdown: You're wrong.


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