[Biturbos4] 2000 S4 Running Hot

Grant gfl1 at optonline.net
Mon Aug 29 20:21:01 EDT 2005

Agreed.  Cool is actually not good.  The only regular failures I know 
of are turbo-related failures in which the oil coked. Coking takes 
place WAY above 200deg.  If you find differently, please contact the 
steel industry - they want your technology badly.  As to "how hot"?  
the flash point for mobil1 is >400deg (F).

Admittedly, the hot underhood temperatures contribute to this, but I'm 
nto sure how much it improves things to extract the heat to the 
radiator, which then blows the heat through the engine bay, which .....

So who's had a turbo failure that ran synthetic, cooled down after hard 
runs, and warmed up in the cold?


And who's had a ring job under ANY circumstances.  Anyone?

On Aug 29, 2005, at 2:53 PM, costco wrote:

> A lot of research has been performed with regards to cylinder wear vs.
> coolant temperature in the 70's and 80's amongst the automakers.
> 192 degrees F is actually optimal in most engines. More or less is
> application specific. I would never put a 160 degree thermostat into an
> engine that prior had a 180 degree thermostat. In many EFI systems that
> alone could cause the engine to run in open-loop "warm up" mode, 
> running
> excessively rich and ignoring the oxygen sensors for short and long 
> term
> fuel maps.
> I know the biturbos run 'hot' but IMO effort would be better spent 
> finding
> a way to get more hot air out of the engine bay than trying to get the
> thermostat to open earlier. The biturbo RS4 has an extended bellypan 
> that
> covers some of the transmission-- this bellypan section is obtainable 
> from
> the dealer for around $120. It wouldn't take much to get it to bolt up
> behind the stock bellypan, and I would definitely give it a try as I
> wanted to before getting rid of my B5. I never got around to doing it.
> The low pressure area there will probably greatly help pull air through
> behind the front tires.
> If you have a little more money to toss around I'd consider 
> retrofitting
> the RS4 oil cooler into the system.
> Next I'd eliminate the foglights, elongate the slits in the front
> wheelwells to promote more air through the intercoolers, and replace 
> some
> of the front lower center grill area with something freer flowing yet
> would still provide some protection from rocks hitting the a/c 
> condenser.
> - Keman
> On Mon, 29 Aug 2005, Greg Amy wrote:
>> efficient. After all, we're not talking about mid-60's
>> muscle cars here; these things run fine on 180F
>> thermostats.
>> GregA
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