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| D2 - Fuel and Exhausts Everything to do with getting fuel into the engine, and fumes back out again |
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#1
25th March 2014, 04:39 AM
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Injector upgrades
A recent compression test on my FL S8 revealed an engine in rude health even after 180,000 miles. However, I feel the injectors could be past their best. If I'm going to change them I may as well upgrade them at the same time. Does anyone know what injector upgrades are available and suitable? I'm not too worried about any increase in fuel consumption as petrol in Dubai is only 28p a litre.
Thanks Steve
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2001 D2 S8. Volcano black. KW Variant 1 coilovers. EBC Turbo grooved discs with Yellow Stuff pads. 19 inch R8 replica wheels with 255/35/19 Michelin Super Sport. In the UK, 1990 Audi 90 2.3 20v Quattro with just 65,000 on the clock and in mint condition. 
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#2
25th March 2014, 05:27 AM
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Anything below 10% increase in flow there is no point changing and anything above 12% will require re-mapping.
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Currently 8less 2011 Q7 S Line 3.0TDI, 2016 Tesla Model S 90D 8 history: 2006 A8 Sport 4.2TDI quattro SOLD, 1997 S8, reached end of life with gearbox failure
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#3
25th March 2014, 06:30 AM
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Erm.........So would that be 11% then?
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 PF late '97 D2 2.8 Aluminium Silver. Solar roof, Full Heated Leather, Double Glazing, 17" wheels, Sports Steering Wheel, Cruise, Blinds, Bose sound.  Fiat Tipo diseasel econobox with all the buttons and none of the soul that now does all the heavy lifting. Ford Capri Laser: noisy, slow, thirsty, bouncy, no buttons but it always sounds like it’s REALLY trying and I can’t help but chuckle when it parps and boings along. And people of a certain age stare at it with a wistful look in their eyes that clearly says…I had one of them. And I sold it because of the kids 
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#4
25th March 2014, 12:24 PM
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yes 11% sounds good lol
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Confidence is the feeling you have before you know better . . . .  Audi A8 D2 3.7 Quattro Sport 1999 FL - Melange 2nd Place Winner - A8-Freunde Annual German Meet 2012 at Edersee 20" x 9" Bentley GTC Wheels with 385mm W12 Front Discs & Bentley Caliper Covers, Front Lowered on Coilovers, Xenons, Combined DRLs and LED Foglights to modified OEM front fog lamp position, Alcantara/Leather, Full Black Alcantara headlining + pillars and blind shelf, Bespoke Flat Bottomed Sports Steering Wheel, Dark Myrtle Wood, Autodim Mirrors, Bose, Blinds, Digital TV, Ski Hatch, Modified rear exhaust section for extra V8 Burble Audi S8 D2 Final Edition 2002, Avus Silver with Red Leather Interior Tiptronic with Sport mode button, Sony rear entertainment package, Bose sound system, Audi Navigation Plus, 20 inch Final Edition alloys, Full Cat Back Stainless Milltek exhaust, giving a great V8 burble Audi A8L D2 4.2 Petrol with LPG - Ebony Black Audi A8L D4 FL 4.0T Petrol twin turbo - Havana Black Audi A2 1.6 FSi Sport - Dolphin Grey with Votex body kit and Red Leather Interior and some other A8's A8L's and Mercs
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#5
26th March 2014, 06:05 AM
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Hmm, wonder how much power could be had with bigger injectors on my S8. Already has aftermarket exhaust with sports cats and x-pipe. I'm thinking bigger injectors, freer-flowng air filter and MRC to map all the mods. 370-375ish?
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#6
26th March 2014, 01:31 PM
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I don't think you will see much if any improvement from injectors. Stock injectors normally have reserve fro 20-30% extra power. You only need bigger injectors once you get to close to the limit of what they can deliver. And even then you can increase fuel pressure to get higher delivery rates. There is really no need to change injectors on NA engine unless you do major changes like manifolds and camshafts.
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Currently 8less 2011 Q7 S Line 3.0TDI, 2016 Tesla Model S 90D 8 history: 2006 A8 Sport 4.2TDI quattro SOLD, 1997 S8, reached end of life with gearbox failure
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#7
26th March 2014, 03:54 PM
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Thanks! That's really good advice, I did think the stock injectors are fine. Also they are only £25 each.
I'm really interested to hear the fuel pressure can be increased, can this be done with the stock pump? I think I read in ElsaWin that standard fuel pressure is 3.5bar? The reason I ask is that I have a dream of a bigger displacement engine swap in the distant future, and that engine would need 60psi or a little more.
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#8
26th March 2014, 04:39 PM
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£25 each? Surely that cannot be right. I bought one from dealer for AHC engine couple of years ago as I could not find one elsewhere and it was around £140.
Fuel pressure regulator for AHC is 4 bar which is highest VAG make I think. It could be lower on other engine codes and if so you could swap in one from AHC engine otherwise it will need to be aftermarket market one and you could get adjustable as well. If you increase pressure by much say to 5 bar or more you will most likely need beefier fuel pump as well.
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Currently 8less 2011 Q7 S Line 3.0TDI, 2016 Tesla Model S 90D 8 history: 2006 A8 Sport 4.2TDI quattro SOLD, 1997 S8, reached end of life with gearbox failure
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#9
26th March 2014, 06:54 PM
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That's excellent! I think 4 bar will be fine. Its just a pipe dream anyway, not likely to happen. The engine I'm interested it is GM's LS3 6.2 litre, its quoted as requiring 60psi which is around 4bar.
I hope its not my memory going bad, it was for the S8 I sold, I took it to MRC and one injector was suspect, they originally quoted something close to £200 but when I came to pay the bill they said the actual price was something like £25. I could hardy believe it too.
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