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#21
23rd July 2009, 06:15 AM
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I hate to be picky but.... The air for the airbox on the V8s is drawn from the front at the bonnet opening down to the botom of the air-box. It should be from a high pressure area of the cars frontage. As a car moves trough the air it forces it over, under and around it. Good article on the benifits of intake location here: Pt1 Pt2 Pt3 Pt4 Pt5 I built a manometer and ascertained that there is little presure drop throughout the 8's inlet tract.
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Conan (the Librarian) Watch it if you dare Currently, 2000 S8, Merlin Purple, Leather Pack 1, Winter Pack 1, SPAX adjustable suspension, AP Racing 6 pot front caliper, 385mm fully floating disks, EBC Yellow Stuff Pads, Black Diamond grooved rear disks and predetor pads, D2 Doctors Brake Block. 1997 4.2 A8SQ - the Projekt. 12 years and ongoing! 1997 4.2 A8SQ - Ming Blue. Restoration sat waiting; saved from the Scrapyard 2003 C5 Allroad 4.2Q - Cobolt Blue. Towing car. Laid up awaiting manual conversion. 2005 C5 Allroad 2.5TDi FE - Grey - Workhorse. 2015 Q3QS SLine - Daytona Grey. Lots of extras! Long Haired Admirals cutter. Previously 2003 C5 A6 1.9TDI FWD - Loaner from D2 Doctor Lifex 1997 S8 - Ming Blue. Loaned out and written off. I loved that car. My first engine swap after cambelt failure. 1996 4.2 A8SQ - Ming Blue. 178k on a cambelt! Trader's 8. Delivered to A8Parts at Lifex. 2003 2.8 A8SQ - powder blueish. Fill in for a while. Sold on. 1998 1.8T A4 Avant FWD. Ming Blue (there's a theme here), PEX for the 97 S8. And a list of non VAG going back 40 years before I saw the light. 
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#22
23rd July 2009, 09:13 AM
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Facelift S8
I was going to have a go at this until I inspected the airbox when changing the MAF and discovered that the secondary air injection and related plumbing may hamper this operation...
any thoughts?
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Present: S4 B8 avant, fully loaded, MRC Stage2, Milltek non-res, KW springs Past: S8 D2 FL, S2 ABY coupe, RS6 C5 saloon, RS4 B7 saloon, S4 B5 saloon, S4 B6 avant, all gone but not forgotten
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#23
23rd July 2009, 10:00 AM
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Short version of post: Drilling Holes?? Making your engine chew on hot air??? Yobs! Bet it sounds nice though
 Bill Long, Waffly, I'm on holiday and bored mindless already, version of post: In addition to Mike I would add that the importance of SMOOTH and fast air flow through the inlet side of things cannot be over stated. lest we forget that the fuel is suspended in said airflow in tiny droplets. Any disruption in that airflow can lead to the fuel dropping out and pooling in parts of the inlet tract. A bad and restrictive thing, very separate from the beneficial "coating" of the inlet tracts on a closed throttle that enables a smooth and predictable transition from open to closed throttle, very important on motorcycles. Much like the exhaust system the inlet side of things is subject to pressure waves and weird harmonics. These are tuned by altering length, diameter and path to produce the desired power characteristics.*# The airboxes role in this is to provide a reservoir of air going in the right direction with no unwanted swirls and eddies at the right temperature. At higher speeds of 50mph or more, on a vehicle with its intake in a high pressure area at the front of the vehicle, the airbox is vital in containing that extra pressure and managing it to the benefit of performance. With respect, drilling holes in an airbox, from a purely engineering point of view, is a bit daft. From an oik's point of view, such as mine  , it's worth it for the noise. Ben your reservoir of knowledge is far greater than mine, I get the bit about cone filters, used them on a spare gsx1100 engine and they were a ******* to jet right at low engine speeds. I don't get this bit "and boxed off so that it only draws air from behind the head lamp. This is a good area to draw from. If drilled carefully then it will give better throttle responce, free-er revving and actually make the engine more efficient as the losses caused by inducting air are reduced....... slightly!" Drilling holes in it stops it drawing from behind the headlight doesn't it.  . I'm being thick and I'm in holiday bored mode and I own a drill and I'm daft enough to start hacking away at things for fun and I've had to use the word OOOPS far too many times so please clarify before I hurt my unsuspecting car, again .Bill *(For those of a nerdy disposition I would recommend digging up the research papers published by Lotus in the late eighties and early nineties on this subject. Their follow up work on hyper efficient two stroke engines is fascinating too. ). #On motorcycles they now have to tune the inlet tracts on sports bikes with bungs and flaps because the inlet side of things was making more noise than the exhaust. Does anyone else recall a car at the meet that made more noise from the front than the exhaust?
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"Man Math" - The means by which a caring husband convinces his wife that a 4.2 A8 is in fact cheaper to run than a tiny Auto crap box "Being in touch with your feminine side" - The ability to, in the 30 seconds following a major accident, obtain your wifes approval for replacing your big german car with another "because otherwise we'd be dead". See also sulking for two years until she finally allows you to get another purely on the basis of your current one being the wrong colour.
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#24
23rd July 2009, 10:44 AM
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Quote:
+
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2009 Audi RS 6 Saloon V10 - 420mm Ceramics, Keyless, Soft Close, Adaptive Cruise, Glass Sunroof, Blinds, Twin Pane & UV, Freeview & DAB, High Beam Assist, MTM bits, Audi Exclusive Bits, MRC, Milltek, GYEF1 ASY2's, Bluetooth streaming music to AMI mod - 753 PS/1021 NM 2016 Audi S3 Saloon, Sepang, S-Tronic - B&O, Tech Pack etc... Company Car 1995 Audi A8 4.2 V8 quattro Sport - Bose, Solar, Blinds
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#25
24th July 2009, 04:30 AM
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How about a vagcom test...before & after
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Just a thought! 
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#26
24th July 2009, 11:53 PM
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Quote:
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Present: S4 B8 avant, fully loaded, MRC Stage2, Milltek non-res, KW springs Past: S8 D2 FL, S2 ABY coupe, RS6 C5 saloon, RS4 B7 saloon, S4 B5 saloon, S4 B6 avant, all gone but not forgotten
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#27
25th July 2009, 08:43 AM
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i already tried this,no increase in maf reading's,a better flowing filter may help,or a larger airbox feed
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#28
4th August 2010, 10:55 PM
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just tried it today and.......
I'm loving the sound my S8 now makes......exactly as described by Singh, so thanks for posting this tip
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#30
22nd July 2015, 05:22 PM
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I can't believe you guys never done this to your XR3i's in the 90's
You'll find that you probably loose a bit of performance (very slightly) but induction noise is very nice. Also possible to open the top of the air box and wedge it open making sure that the filter stays in the top part. You can always close it then if you don't like it. Also a second air box might be worth while.
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1996 A8 4.2 QS. Bose, Solar roof, um...um... rally sport towbar. Now gone to a new home as the Traders 8. Bright yellow bus o love.
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