[Biturbos4] Turbos Reliability & Replacement Cost (was: 2000 S4 Running Hot)

j y jimnetpa at yahoo.com
Wed Aug 31 16:31:12 EDT 2005

Depending on your $$$....I would upgrade the exhaust (look at AWE, Milltek, etc.) to a TRUE dual. The stock S4 exhaust is a bottle-neck - even for K03 turbos. I would then consider a chip (if u haven't done this yet). If you purchase the chip first - the turbos will be spinning so hard (especially with GIAC-X) that you will defintely get too much back pressure and potentially cause K03 (turbo) failure. 
That's why I recommend opening up the exhaust first. If your piggy bank is fairly big...then u might want to add DPs (down-pipes) to your exhaust uppgrade list. There are two approaches here...Piggie Pipes..where the pre-cats are gutted (the S4 has 4 cats for the un-informed)..or purchase DPs that have the pre-cats totally eliminated. 
By upgrading to a true dual exhaust and adding DPs, you will have eliminated most of the restrictions on the "hot" (exhaust) side of your K03s. Thus, they will spool up faster and giev you even MORE of a kick in the pants. 
The downside is potential turbo overspin which can kill your K03 turbos...so far..this has NOT happened to me...I've had a true dual/DPs with no-cat set-up for almost a year...I run my car hard (boost to 19 psi)...which I know isn't wise. If you purchase the chip (GIAC, AMS, APR, etc.), the dual exhaust, and DPs, you will be considered Stage 2+ (with Stage 3 - K04 turbos - being the hightest). Expect to have spent at least $1500 - $2000 (USD) for a typical Stage 2+ set-up, depending on where you source your parts, and whether they are used, or new. 
If you decide to modify the "cold" side (intake) of your S4, you will reduce "heat soak" on your K03s by purchasing AWE or stock RS4 ICs (intercoolers). The stock ICs can handle a Stage 2+ S4, but you will be putting a strain on them, especially during the summer. AWE ICs will cost about $1200 (USD) plus labor to install. I installed AWE ICs on my S4. 
At this point, your S4 will be considered Stage 2++ (a hair under Stage 3-, K04 turbos, using K03 fueling). 
There has been some debate on whether a K&N set-up is better than the stock airbox. Based on my VAG run logs, KEEP THE STOCK AIRBOX, the argument about the K&N set-up flowing better is BS! You will do nothing but breathe HOT ENGINE AIR with the K&N set-up which will adversely impact your MAF readings and timing. 
Oh yeah...dont't forget to upgrade your DVs (diverter valves)...personally..the Bosch 710Ns are as good as any Hyberboost, Forge, or Bailey DV. Plus, they cost $35 ea (USD) and are a OEM item on the Audi TT. Just go to your local Audi (or Volkswagen) dealer and ask for them. You will need two..you can install them yourself...in under 20 miniutes. I wouldn't upgrade my DVs unless I was chipped. 
At the end of the day...to go from a stock S4 (Stage 0) to Stage 2++  will set you back approximately $3500 (USD). Hope this helps.

Rohan Singh <rohanj_singh at yahoo.com> wrote:
Thanks for the tip JY. I know very little about
upgrades so it is certainly helpful to get guidance in
the planning stages. I like the idea of a gradual
upgrade as I don't have big bucks to spend
immediately. Where does one typically start if one
could spend a couple thousands dollars to begin with?
A chip comes to mind, but I guess that is the fastest
way to the demise of the existing K03 turbo's!

--- j y wrote:

> Well.......
> If you haven't made mods to the exhaust (larger true
> dual exhaust, removed pre-cats from DPs) and intake
> (APR Bi-pipe or SAMCO TBB, larger ICs) then you will
> NOT realize the potential of K04s. I would NOT
> recommend putting K04s on Stage 1 (just a chip) S4
> w/o the aforementioned upgrades - first. 
> Even after the aforementioned upgrades, you should
> also upgrade the fueling, MAF, Y-PIPE, turbo intake
> hoses, etc. This will set you back some $$$.
> In my opinion, it's BEST to SLOWLY work your way up
> to a K04 (Stage 3) set-up, unless you have mucho $$$
> burnin' in your pocket. Believe me, a stage 2, 2+,
> 2++ set-up will put your S4 in a different category
> - not quite Stage 3 - but awful close. You WON'T be
> disappointed!
> Rohan Singh wrote:
> Thanks for the info Quincy. I'll begin to save up!
> Any
> opinions on whether it is worth switching to Ko4's
> on
> a car with around 100K kilometres (About 62K miles)?
> I'm planning to keep the car to the very end so
> maybe
> it is huh?
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