[BiturboS4] Blown turbos

Edwards, Dave Dave_Edwards at iOra.com
Thu Sep 5 10:04:52 EDT 2002

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I have read a number of posts from Americans about hearing a 'siren-like'
noise, and some replies saying that its normal. All I can say is that over
here we don't have any reports of such a noise. Just maybe there is a
difference between US and Euro S4 which means the turbo is noisier for the
US car, but I can't think why. I assume that you have warranty for your car?
If so don't chip until you are sure that the turbos are OK. Surely there
must be an independent tuner near you who could give an impartial opinion on
the noise?

I might check up on the Hyperboost valves myself in that case. I'm not happy
that the Forge DVs don't fit well with the APR bipipe, but in general the
Forge is favoured in the UK by S4 and RS4 owners. A lot of S3 owners are
however unhappy with the Forge DV for their car (different model DV) and are
actually returning to the Bosch valve (quicker response) and replacing it
regularly, which is OK as its quite cheap. I don't think the Forge valves
leak or stick (like my previous Bosch ones did) but I think that they are
slow to close.

The S4 clutch should be fine for a stage I or II upgrade. Having said that
with the reports of clutch problems on this list, maybe Audi has used a
substandard part in the US model? I have not read any reports of early
clutch failure on Euro S4s.

For a boost gauge it depends entirely what sort of display you like. Most
add-on boost gauges look exactly that. Some people have put a lot of effort
to integrate the gauge with the car. Check out the tech articles on
Audiworld. My choice was somewhat easier as I wanted both a boost gauge and
a turbo timer. Therefore for many reasons (mostly value for money) it was
best for me to get a combined boost gauge and TT. I only know 2 of these:
The Defi HUD and the Blitz Dual TT. I have used the Blitz before on a Subaru
WRX, and its a good unit but there are not many good places to mount the
display so that it is convenient to read. The Defi HUD is slightly more
expensive but is a superior unit. The display reflects off the windscreen to
you can read it without taking your eyes off the road. Also its better than
the Blitz because it has a remote boost sensor so that you can keep the air
line very short. I have hooked up my TT so that it forces the turbo coolant
afterrun pump on for 5 minutes after shut-off, much better than leaving the
engine to idle.

 -----Original Message-----
From: California Fields [mailto:cfields72 at hotmail.com]
Sent: 04 September 2002 19:29
To: Dave_Edwards at iOra.com
Subject: Re: [BiturboS4] Blown turbos

Hi Dave. Thanks much for the info. I bought my car used with 9k miles and
I'm just trying to get a handle on what to look for in the way of problems
(or preventative maintenance).  With the windows down, I can only hear a
faint whistle when the turbos spool.  With the windows up, I can't hear any
whistle but I can hear a faint "siren" noise...I was thinking this is normal
turbo sound through the engine compartment.  I'll keep an eye on it.

I"m going to order the HyperBoost diverter valves because, acording to
Stratmosphere, they are superior to the Bailey and Forge.  I will also
replace the TBB with the Bipipe.  Also up to bat are: Strat short shifter,
Miltek 3" cat-back, and either GIAC or APR chip.  Does anyone ever bother
replacing the clutch and plates? Or is that only if you go Stage III?

Which boost guage do you recommend?

Thanks, Carter.

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