Lewbo

As I sit in the car after a good session of hard driving - I always wonder how long I should leave the motor running to cool the turbos, usually I wait for 3-5 minutes is this long enough, I have owned turbo charged cars before but I've never fitted a turbo timer - as I probably wouldn't trust it to shut the car off after ticking over for a while. What are the proper cool down time and what exactly is the potential damage if not cooled down correctly.

ltc

~ 1-2 minutes is generally discussed/recommended (perhaps a bit longer if you were on track and didn't do a long cool down lap).

wross996tt

As stated above, 90-120 seconds. After that you heat soak.

slant911

I believe the bearings get cooked and fail leading to a wobbly turbine.

ltc

For a definitive/expert answer on what goes wrong on a (non cooled down) turbo, I'd suggest asking Kevin and/or Stephen.
IIRC, there have even been pictures posted previously.

Joe Weinstein

heat-soak while idling? Please tell me more about this.
Joe

k4site

I thought that delaying turning off the engine was to make sure that the turbo's speed was decreased before the oil supply was interrupted.

MidnighTT

I thought it was to let oil circulation carry heat away from the turbos. At least, that's how I rationalize not doing a cooldown after a 4 minute drive to the store.

Jeff

Kevin

https://rennlist.com/forums/964-turbo-forum/353255-cool-down-time.html

Tim Wasmer

I thought cool downs were only applicable to Air Cooled cars? Per Si.

Kevin

The 996TT shares the same basic turbocharger as it's older brother. Both are Not water cooled.

iman11348

I have read all the posts on this topic and am still confused. It sounds like the consensus and expert advice (Kevin) is to cool down after hard runs. What is the recommendation for ordinary daily driving? To idle or not to idle?

Joe Weinstein

I always let it idle at least a bit. 30 seconds if the car
has had *zero boost* for the last 5 minutes of driving.
Cheap insurance; just think of the oil that gets caught
in the turbo bearings, having to sit there till you restart.
You want the turbo cooled down enough that it's heat
won't burn that oil into a sludge that will ruin the bearing.

Wachuko

I always take it easy for the last few miles before getting home or my destination and then let it cool down for a minute or two before I turn it off.

Too bad they did not use a similar system as in the 951...

Streetfighter

Just my two cents, but I have an Audi S4 twin turbo and what I do is take it easy for the last few miles wherever I am going. Once I reach my destination I let the car idle for a minute or so. I have never had any issues, granted I don't have a Turbo, but it would seem to me that if you run the car hard let it cool down a little bit longer than the normal driving sessions would permit.