While some people may look at my AZ join date and think of me as a "noob", the fact is that I've owned my 2002 S4 Avant since April of 2003 and logged about 100K miles in the driver seat. The fact is I have designed, built and tuned a GT based turbo system back in my VW days, so I have at least a little bit of a clue about what projects like this entail. The fact is I have a funny little problem called "DIY disease".
Whether it's building giant subwoofers, high end road bikes, PCs, or turbocharged cars... sometimes I get a little carried away, and sometimes I wind up doing it THE HARD WAY. So I think that's the perfect theme for this project and build thread! 
I bought my S4 shortly after becoming a father and deciding to sell my Honda CBR1100XX (crotch rocket). The '88 Scirocco 16V 2.0 turbo wasn't much of a family car and frankly I was just plain sick FWD and wheelspin. Having owned Passat wagons in the past, I liked the idea of an Avant: a car that's practical, versatile, relatively safe (ABS, airbags, etc.) and somewhat of a sleeper with some real performance potential. So it wasn't long before the B5 S4 bubbled to the top of my list and became the inevitable car of choice for my puporses: a twin-turbo all-wheel-drive 300HP grocery getter. What's not to love?! I wound up locating a Santorin 6MT Avant in Wisconsin with just 22K miles on it and so I flew there to buy it and drive it home. I managed to get the car home without completely destroying it but not before a large truck tire retread appeared out of the darkness on I-90 and did $2500+ worth of damage to the front end.
"Old & busted"
That quickly put me on the path to getting an RS4 bumper, which put me on the path to getting RS4 front fenders, and so on... and so on... until finally I wound up doing the whole bloody widebody conversion with a lot of encouragement from the hooligans on AudiWorld, Josh Decker @ Achtuning sourcing the parts, and Queen City Auto Rebuild of Redmond, WA, doing the body work.
"The New Hotness"
That pretty much wiped me out financially, so I concluded the performance mods would have to be minimal. I'd just chip it and drive it until the K03s blew. Well, to make a long story a little less long... those pesky little K03s never blew! But one of them is leaking a bit of oil into the intake and my clutch started slipping, so finally...
THE TIME HAS COME.
My S4 as it is today after 7 years of daily driving since the widebody conversion:
Now if I wuz a smart man...
I'd just buy a VAST GT kit or drop the car off at AMD and get it all TiAL'ed up. But due to the dreaded disease I just gotta be "different". My power goals aren't all that lofty but I've been wanting to upgrade to GT turbos of some kind for a long time and decided that old school journal bearing turbos were out of the question. In a nutshell my performance goals are: better than K04 power with good efficiency and decent spool. If I could make 450 AWHP on straight 92 octane pump with a healthy torque curve, I'd be pretty happy. I think I'll be pretty happy no matter what, but the fun part will be seeing what kind of power to boost ratio and spool characterstics I can get out of this build. After studying compressor maps like a mental patient and flirting with the idea of BorgWarner EFR or TiAL turbos, I finally decided on the GT2859R because it has a high efficiency compressor stage that was designed for an engine not entirely unlike the 2.7T: the 2.6 liter twin-turbo 6-cylinder Skyline R34. I believe this particular turbo offers the greatest overall efficiency among GT25 and GT28 models capable of 30-35 lb/min airflow from surge line to choke line. It also uses a smaller trim version of the improved NS-111 turbine wheel (compared to GT25) which in theory should offer decent spool and exhaust side efficiency.
Current mods:
RS4 Avant Widebody Conversion
Flik Artic 18x8.5 wheels spaced to ET20
255/35/18 Toyo T1-R tires
Stasis Street Sport coilovers
AMS chip
Forge 3" exhaust
Planned mods and parts list for "the build": (TBD = To Be Determined)
Turbochargers: Garrett GT2859R
Exhaust manifolds: Custom tubular, 304 SS, Schedule 10 pipe, CNC'd flanges by Sam@BMCRace
Downpipes: TBD... Custom/DIY or VAST or ? with V-band connections & high flow cats.
Cat back: Custom/DIY 3.5" single 304 SS 16 ga
Intercoolers: Wagner RS4 w/carbon fiber shrouds
Inlet piping: TBD... Custom/DIY or ?
Bi-pipes: TBD... Custom/DIY or VAST/ARD or ?
Cold air intake: TBD
Fueling & tune: AMD/EPL with single in-tank Bosch 044
Meth: Aquamist HFS-3
Clutch: TBD... CM FX850 or ??
Clutch slave: VAST metal slave unit w/stainless line
Other upgrades & replacement parts:
Control arms: 034 adjustable uppers & street density lowers
Tie rods: 034 heavy duty tie rod ends
Engine mounts: OEM RS4
Snub mount: VAST
Cooling: VAST medium flow EFK
Wish list:
JHM solid shifter kit
Transmission mounts
Rear diff mounts
350mm Cayenne Caliper BBK up front
Some kind of BBK for the rear
Forgestar F14 18x9 wheels
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