air filters on turbo cars

1. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

   #1 4th January 2010, 21:27

   hello
   
   i have a question about air filters on turbos and i would like some opinions on what i think.
   
   as some of you may know i got rid of my vts in august as i needed something alot cheaper to run as i am now a student again, so i bought a GT TDI golf.
   
   engine wise i had it mapped, 2.25 inch down pipe made and a panel filter, making a healthy 146.5 hp aand 400nm of torque (PD115 engine)
   
   the question i have is the cold feed to the air box is VERY restrictive, i mean at one point its approx 25mm in diameter. and im thinking what is the point of a cold feed on a turbo car when before the air enters the inlet manifold it goes through a very hot turbo then through the intercooler (i have the OEM side mount btw) and then into the inlet manifold.
   
   this cold air feed is clearly starving the engine of air so would i be better;
   
   1.leaving it as it is
   2.removing the cold air feed
   3.removing the cold air feed and widening the inlet to the air box
   4.open cone filter
   
   and ideas or opinions welcome
   
   thanks
2. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

   #2 4th January 2010, 21:35

   surely heat soak is not an issue with the air passing through the hot turbo in either case?
3. ryanmt Established Member Joined: Oct 2004 Warrington Posts: 1987 AX VTS 57 3.0 TDI A5

   #3 4th January 2010, 21:36

   cold air feeds ain't so critical on turbo engines since any air temp difference is going to be negated when the air gets compressed (generates heat in itself) by an already hot turbo like you said. So you are best off with just an open cone filter really and letting the IC do its job.
4. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

   #4 4th January 2010, 21:39

   Quote:

   Originally Posted by ryanmt cold air feeds ain't so critical on turbo engines since any air temp difference is going to be negated when the air gets compressed (generates heat in itself) by an already hot turbo like you said. So you are best off with just an open cone filter really and letting the IC do its job.

   thats what ive been thinking but the reason i ask this is is because on the golf forums they all seem to be raving about R32 snorkel pipes (granted they are alot bigger than my snorkel pipe) but i couldnt really see the reasoning behind it
5. Sparco_Tom Saxperience Addict Joined: Jan 2007 Aylesbury, Bucks Posts: 12836 Yeaaahh Fiesta

   #5 4th January 2010, 21:44

   nice open cone filter, a cold air feed is still useful. Obviously if the filter intake temp is lower once its passed through the turbo and intercooler its going to be a little cooler when entering the cylinders.
6. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

   #6 4th January 2010, 21:48

   im thinking of trying it without the snorkel pipe removing the restriction, so just the air box with no cold feed to it. that should be more free flowing.
7. Sparco_Tom Saxperience Addict Joined: Jan 2007 Aylesbury, Bucks Posts: 12836 Yeaaahh Fiesta

   #7 4th January 2010, 21:50

   on your golf i cant see it make a noticable difference but when you are talking 400+bhp turbo it makes a small gain
8. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

   #8 4th January 2010, 21:51

   Quote:

   Originally Posted by Sparco_Tom on your golf i cant see it make a noticable difference but when you are talking 400+bhp turbo it makes a small gain

   you should see the bore of the intake, it is literally 25mm tops
9. Sparco_Tom Saxperience Addict Joined: Jan 2007 Aylesbury, Bucks Posts: 12836 Yeaaahh Fiesta

   #9 4th January 2010, 21:56

   i have never looked at the standard setup, most my mates use cold air feeds or r32 pipes
10. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

    #10 4th January 2010, 22:00

    http://garychandesign.net/gti/sale/airbox.jpg
11. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

    #11 4th January 2010, 22:04

    http://gti25.gt.funpic.de/albums/use...l_HPIM0539.JPG
12. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

    #12 4th January 2010, 22:05

    there is a large difference in nominal bore between the two, my point is it worth the money for the bits when i could just leave the end of the air box open to the engine bay as the air will be hot any way?
13. SaxoJamie Saxperience Forum Bum Joined: Jul 2007 Sussex Posts: 3891 2x 106 GTi

    #13 4th January 2010, 23:03

    Quote:

    Originally Posted by gouldy87 there is a large difference in nominal bore between the two, my point is it worth the money for the bits when i could just leave the end of the air box open to the engine bay as the air will be hot any way?

    see how it performs like with just the feed removed or maybe just go for an open cone filter, the larger the air filter the better so I've heard
14. webby Established Member Joined: Jul 2007 manchester Posts: 2456

    #14 5th January 2010, 09:51

    drill the airbox lol.
    i dont know what it will do but they make a cool sound a friend has it done it on his passat
    
    an open filter could possibly make things a tiny bit better.
15. gouldy87 Saxperience Forum Bum Joined: Jun 2008 Posts: 3932

    #15 5th January 2010, 14:33

    you can really feel it struggle higher up the revs like its struggling to breath, i was going to have a play around this afternoon but with 3 inch of snow i will wait till the weather picks up abit.
    
    thank you all for your input