turbo owners : do you wait for the turbos to cool down _

Hi there, Question for TT owners : after a spirited and/or long drive, do you leave the car to cool down the turbos ( leaving it working but not revving ) for a few minutes before turning it off ? Ive heard both things : people that ALWAYS do it on 996 TTs others with 996 TTs that say that was with pre 80´s turbos that need for us to do that. Whats your poison ?

Personally I always drive slowly the last few miles home giving the engine time to cool down. I've read that if you want to avoid the occasional puff of smoke at start up then it's a good idea to leave the car idling for 2 minutes before turning off the engine - but who has time to sit around for 2 minutes :dont know:

You should really allow them to cool before switching off as these things can glow white hot under track conditions! They spin at 150,000 rpm and if they stop spinning while at very high temperatures the lubrication boils dry and can block the oilways with residue... OK, road cars don't get quite as hot, but you still wouldn't want to touch it after a spirited run :hand: Aside from the turbos, always try and cool the engine a bit before you put it away in the garage, as 'hot-soak' can cause all sorts of issues (like setting fire to the houses of some early Volvo turbo owners!)

My 2 cents... The early 80's introduced the turbo charger to the masses and also introduced turbo charger problems after 60,000 miles. The problems were due a couple of factors. Old designs and poor quality oils mainly. Old designs - turbos when originally introduced weren't water cooled. They only had an oil feed to provide cooling and lubrication to the turbo bearing. Now all turbo's are water cooled (where a car uses water ) This allows the bearing to stay cooler and stops the oils from burning and coking up (going solid) in the bearing section. This was the cause of the oil burning and wearing of the seals. Poor quality oils - ie, lack of synthetics, mineral oils etc that couldn't handle the heat of the turbo charger and would again, burn and coke up wearing the turbo and also the engine as the oil would break down thanks to the turbo. This is why you had to change the oil so often many years ago.... Ok so today with water cooled turbos, and top quality oils, coking doesn't exist in normal usage. If I was tracking my car I would come into the pits and run it for 5 minutes before shutdown, but for daily driving, take the last mile home off boost nice and gentle and all will be fine.... Jeff

As per the others really, the last 1/2 to 1 mile dead easy then about 45seconds on the drive b4 switching off 8)

Firstly, you won't be able to "cool" them unless you wait hours! Take it easy the last 1/2 miles. If you rag it and then immediately switch the motor off you increase the risk of damage to the turbo(s). If you forget to take it easy then let the car idle for 1-2 mins before killing the engine(and pop the lid) If you track the car then use the cooling down lap to get as much heat away as possible then pop the engine lid after each session. Excessive heat and/or oil starvation(or combo of both) is the main reason for turbo damage.

As per Wattie really. A cool down (either stationary or gentle off-boost/no load run down over last mile or so) will allow the turbos to flush out/burn off/oxidise any unburnt hydrocarbons (sooting/coking) with high oxygen content lean burnt exhaust and allow normal to low turbo running temperature to be attained along with full lubrication (lubrication oil burns off at high turbo speeds) to return. As much as turbo technology has advanced, particularly water cooling, Subaru for example still sticker advice to run engine for two mins after spirited drive for the above reasons. I don't have a Porker Turbo manual, but odds on it stipulates similar advice. I even let my NA cool down after a fast run. It's called basic mechanical sympathy (after all, we all know we should warm down ourselves after we exercise). As for who has 2 mins to let their car cool down, well if any one does it's the Turbo owners! What else are they going to do while they wait for us mere mortals to catch up?

I let my one idle for a little while then turn it off. At a guess about 1 + min?.

Apparently any turbo should be allowed to cool down a tad from even normal running, failure to do so results in crystalising of the oil lubricating the turbo, through over heating it, at switch off. The crud formed is then circulated throughout the engine when flushed out of the turbo next time the engine is started, resulting in blockages in the oil ways. Ask my mate, whose TT Coupe suffered terminal engine failure at 140K because of this very issue.