Air Holes in stock Air Box - Why ?

[teeerex]

Hi,

Just wondering why the stock air box has lots of factory holes in the right bottom of the air box ? These are clearly in the engine compartment sucking up nice hot air ? (ie not good). They clearly pick up their fair share of the air because the immediate filter above them is dirtier than the rest after only 1-2000 miles .. Mind you, I guess any air from the engine compartment / lower to the ground will be dirtier than on engine lid...

Are porsche sacrificing a tiny bit of performance for some added induction noise - or is the funnel to the engine lid too restrictive at full throttle ?

I'm tempted to block them up to see what difference it makes ... anybody else done this or have any ideas ?

?

Richard.

[kam]

Hi,

Just wondering why the stock air box has lots of factory holes in the right bottom of the air box ? These are clearly in the engine compartment sucking up nice hot air ? (ie not good). They clearly pick up their fair share of the air because the immediate filter above them is dirtier than the rest after only 1-2000 miles .. Mind you, I guess any air from the engine compartment / lower to the ground will be dirtier than on engine lid...

Are porsche sacrificing a tiny bit of performance for some added induction noise - or is the funnel to the engine lid too restrictive at full throttle ?

I'm tempted to block them up to see what difference it makes ... anybody else done this or have any ideas ?

?

Richard.

Are you sure those are factory holes?

[1999Porsche911]

They are factory holes and serve no performance purpose. Increases noise level and drains any water in flter housing. You are correct that it increases intake temperatures which hurts performance.

Edited December 2, 2005 by 1999Porsche911

[teeerex]

They are factory holes and serve no performance purpose. Increases noise level and drains any water in flter housing. You are correct that it increases intake temperatures which hurts performance.

OK - tks for replying.

Just to satisfy my curiosity, I blocked the holes with gaffer tape and put the air box back together again. I noticed immediately that there was substantially more 'suck' now on idle from the snorkle to the lid - infact I nearly caused the engine to stall as my hand was sucked hard onto the tube. I guess this is 'correct' as the air now had no other point of entry.

Performance wise, the car did seem a bit more hesitant, little less induction noise - but that could be me - nothing scientific ... :-)

So lets say that 30% of the air comes from these holes as opposed to the main duct - I guess getting a cool air supply to the 'other' end of the air box may give a small % performance increase ...

Hmmm something to consider as I only have a layer of thin fiberglass between another snorkle and the 'fake' vent in the right hand side of my Aero spoiler ...

Watch this space ...

Richard.

[gcp]

Richard, I had the exact thoughts as you before I replace the stock airbox with an EVO induction system. What held me back from taping the factory made perforations was H2O accumulation. The water has to drain from the airbox some how. The real question is are all those holes needed for draining alone? I am surprised that you noticed a hesitation when taping the factory holes :oops:

Thanks for sharing inputs.....

[teeerex]

Richard, I had the exact thoughts as you before I replace the stock airbox with an EVO induction system. What held me back from taping the factory made perforations was H2O accumulation. The water has to drain from the airbox some how. The real question is are all those holes needed for draining alone? I am surprised that you noticed a hesitation when taping the factory holes :oops:

Thanks for sharing inputs.....

Hi - to be honest, I don't believe that is the primary function of these holes. The water must exit at the 'lowest' point which is hole in the bottom of the air box - made obvious by the water marks leading to it. This hole also deposits any water in the gap behind the engine by the belts and onto the floor - no I believe those holes are 100% for air intake or balance only.

Taking another look at the holes - getting cool air to them is going to be more of a problem than I originally thought due to the a/c lines - there isn't much room in there...

I'm taking the tape off for the moment, but may cut a second hole into the sub frame of the Aero kit just to feed it cold air by convection ....

Thanks for your thoughts...

Richard.

[eurotrashed]

I noticed when I have opened the airbox, it looked like some water had been sitting in that lower trough. So, I ended up drilling a few small holes in the lower trough for water drainage. I did not notice any difference in sound or performance after that. Not sure what this does to the equation, if anything, but at least now I know that if water gets in there, it can get out.

Sean

[SPR]

I taped them close. I then removed them. I think that although it is a source of hot air, the increase air flow does make a difference, at least it seemed that way when I removed the tape.

I noticed when I have opened the airbox, it looked like some water had been sitting in that lower trough. So, I ended up drilling a few small holes in the lower trough for water drainage. I did not notice any difference in sound or performance after that. Not sure what this does to the equation, if anything, but at least now I know that if water gets in there, it can get out.

Sean

[gcp]

Richard, I had the exact thoughts as you before I replace the stock airbox with an EVO induction system. What held me back from taping the factory made perforations was H2O accumulation. The water has to drain from the airbox some how. The real question is are all those holes needed for draining alone? I am surprised that you noticed a hesitation when taping the factory holes :oops:

Thanks for sharing inputs.....

Hi - to be honest, I don't believe that is the primary function of these holes. The water must exit at the 'lowest' point which is hole in the bottom of the air box - made obvious by the water marks leading to it. This hole also deposits any water in the gap behind the engine by the belts and onto the floor - no I believe those holes are 100% for air intake or balance only.

Taking another look at the holes - getting cool air to them is going to be more of a problem than I originally thought due to the a/c lines - there isn't much room in there...

I'm taking the tape off for the moment, but may cut a second hole into the sub frame of the Aero kit just to feed it cold air by convection ....

Thanks for your thoughts...

Richard.

Here's my set up with the EVO induction system. I don't much like the design because it seems to me it suck in more hot air than cold....but it works well so I can't argue with success.

Edited December 5, 2005 by gcp

[SPR]

doesn't look that hard to build an enclosure around the top of it using plastic container large bottle and cutting it and maybe pop riving it or using pem nutz with the foam sealing tape. If you don't like it take it off.

Richard, I had the exact thoughts as you before I replace the stock airbox with an EVO induction system. What held me back from taping the factory made perforations was H2O accumulation. The water has to drain from the airbox some how. The real question is are all those holes needed for draining alone? I am surprised that you noticed a hesitation when taping the factory holes :oops:

Thanks for sharing inputs.....

Hi - to be honest, I don't believe that is the primary function of these holes. The water must exit at the 'lowest' point which is hole in the bottom of the air box - made obvious by the water marks leading to it. This hole also deposits any water in the gap behind the engine by the belts and onto the floor - no I believe those holes are 100% for air intake or balance only.

Taking another look at the holes - getting cool air to them is going to be more of a problem than I originally thought due to the a/c lines - there isn't much room in there...

I'm taking the tape off for the moment, but may cut a second hole into the sub frame of the Aero kit just to feed it cold air by convection ....

Thanks for your thoughts...

Richard.

Here's my set up with the EVO induction system. I don't much like the design because it seems to me it suck in more hot air than cold....but it works well so I can't argue with success.

[teeerex]

... so it costs £300+ for a plastic box and a cone filter - and it still sucks in the hot air because it not enclosed ... :-(

I originally thought the bootlid 'sealed' the Evo box when shut, but looking at the picture in detail - this doesn't seem to be the case...

.. Hmmmm .. think I'll stick to a DIY case which I know feeds only cold air ...

[reddahaydn]

delete

 

Edited July 18, 2018 by reddahaydn