Turbo question
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Turbo question
Just curious, does the 997TT need to idle for awhile after being run hard to prevent coking? Is this even necessary with modern turbos?
Last edited by 2thfixr; Oct 13, 2007 at 10:50 PM.
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i would do it as a precaution. i have done a few minute cool down on every turbo car i've owned that didnt have a turbo timer. allowing the turbos to cool down especially after some spirited driving can never hurt so i would recommend it.
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I cannot say if the 997 Turbo has this feature for certain, but B5 Audi S4s have a built in system that continues to cycle coolant through the turbos even after the car is turned off, depending on operating temperature.
http://www.audiworld.com/tech/eng37.shtml
http://www.audiworld.com/tech/eng37.shtml
Well, /WHY/ not take advantage of your S4tt's built in after-run coolant pump circuitry? "Woah, hold on there.. afterrun pump.. what is that?" Audi engineers are very smart, and they plumbed in a small reverse-flow electric coolant pump to cool the turbos AND push any possible air/steam created in the turbocharger waterjacket into the transparent plastic coolant reservoir. Additionally, it runs the electric pusher fan and the electric puller fan at approx. 40% duty cycle for up to 10 minutes-- all of this after the engine is turned off. You may or may not have ever heard this neat little system turn on. The reason why is the thermostat for it is set to something very, very high. I don't have the details but my guess is it's set to 240 degrees F. Unfortunately, the measured coolant temperature is not directly related to turbocharger temperature. A slight oversight on Audi's behalf, but it would cost a considerable amount to measure the turbos temperature more accurately.
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997TT tend to keep the fan running or would automatically switch it on if temp. is abit high... not sure if that has anythin to do with the turbo timer or anything but since i got my 997TT ive been hitting it hard and would sometimes just switch it off in a hurry and havent had a problem with it yet. it tends to get the fan on automatically later on though.
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Look at it this way, it can't hurt and might help to let the turbos "cool down" for a minute before shutting down. I also warm the car up for a couple of minutes before I take off in the am and I never hammer it until up to operating temp (at least 180f).
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2th,
The 60-120 seconds you drive it gently down your street or parking her after driving it hard is plenty of cool down time, which I personally think is a non-issue today anyways. However, if it helps you sleep better at night
-m
The 60-120 seconds you drive it gently down your street or parking her after driving it hard is plenty of cool down time, which I personally think is a non-issue today anyways. However, if it helps you sleep better at night
-m
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Also, I'm not sure if Porsches have this feature, but the open door chime on VWs and Audis lasts exactly one minute, which can be a helpful "pseudo-timer" in place of hacking up the dash wiring for a turbo timer.
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If you listen very carefully you can hear the pump running after shutdown. While doing this don't be alarmed if the fans kick in and scare the living daylights out of you!
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I cannot say if the 997 Turbo has this feature for certain, but B5 Audi S4s have a built in system that continues to cycle coolant through the turbos even after the car is turned off, depending on operating temperature.
http://www.audiworld.com/tech/eng37.shtml
http://www.audiworld.com/tech/eng37.shtml
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