[Biturbos4] After-run thermoswitch modification

Ti Kan ti at amb.org
Sat Nov 17 15:04:44 PST 2007

Rocket Science Racing writes:
> The original article presented data showing only a 5 degree improvement in
> the measured temperatures 15 minutes after shutdown. This is the proverbial
> fart in a windstorm from an engineering perspective and neither worth the
> effort nor the extra wear on the battery. It's a "feel good" mod.

Yes, I read the results, and the author admits that it was "highly
unscientific", and the conditions were different between the two tests.
The low-temp thermoswitch test was conducted at 7 deg.F higher
ambient than the stock switch test.  Not only that, he only drove the
car 10-15 minutes from a cold startup without going into boost in
both cases, so I don't think the engine really got very hot.
If I drive only 10-15 minutes without boost, my oil temp gauge doesn't
get var far off the left peg.  If he had driven the car harder/longer,
I think the after-run system would've shown a larger reduction in temps.

I'd be surprised if the after-run system is as ineffective as
his tests would suggest, because if it was, then Audi wouldn't have
put it in there in the first place.

His tests also doesn't show underhood temps, which in our S4s
cramped engine bay could get very hot, and could partially explain
why there seems to be higher rate of turbo failures in S4s compared
to A6 2.7Ts.

Maybe it is just a "feel good" mod, but it certainly doesn't hurt
anything and could only do _some_ good, significant or not.


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