993tt - turbo cool down?

[kennyboy]

Years ago I had to wait a few minutes in my Renault 5 GT Turbo for the turbo to cool down before switching off... if I didn't it would reduce the life expectancy of the turbo I was told...

I take delivery of a 993tt next week and was wondering if owners are doing this on their 993's too?

I couldn't believe it when I first read it on rennlist - or is it people just being over cautious?

 

[cbonetti]

I always let my 993tt cool down at idle for a couple of mins after spirited use.
Its not that much effort, and I'd rather be safe than sorry.
If I remember rightly it does recommend this in the owners manual, but happy to be proved wrong

 

[kennyboy]

Thanks Carlo, I shall do the same then.

 

[Gordon Attar]

I try to do the same (based on the Rennlist advice) much to the annoyance of my neighbours as it has rather loud set of Fabspeed muffler bypasses, usually it takes most of that time to park open garageand put away If I've not had the Turbo working ie town driving I tend not to give it so long.

I have also not found anything in the manual on the subject !!!

Good luck and enjoy

 

[FLAT-SIXY]

While on the le mans classic trip with porsche centre cambridge this summer, I asked this question to aftersales manager Gary sorrell. He shook his head a said, the last time it was nesesary to whind the engine down and let the oil drain out of the turbo was on the early garret 911 turbos. He said you can turn the car of imediatly.
But i still let mine whind down for about 30 secs enough i think for them small k16's. But do as you think best.
And congrats on your new purchase, welcome to the club.

 

[RichardLW]

944 turbos have a thermostatic switch which allows pumping oil until the innards have reached a sensible temperature and static oil won't be turned to solid carbon. Even then, I would always let mine stand for a couple of minutes before switching off but you could hear that little pump running for quite a while on a hot day. Presumably tts have the same sort of thing?

 

[kennyboy]

Thanks for the welcome guys - I don't think I'll be sleeping properly until she arrives next week! [8D]

Expect a deluge of postings from me..

Richard - yeah I'm sure they do, saw something about this on rennlist plus a fan stayed on in the tt engine bay for ages after the test drive..

 

[JBL930]

ORIGINAL: dongawoy

While on the le mans classic trip with porsche centre cambridge this summer, I asked this question to aftersales manager Gary sorrell. He shook his head a said, the last time it was nesesary to whind the engine down and let the oil drain out of the turbo was on the early garret 911 turbos. He said you can turn the car of imediatly.
But i still let mine whind down for about 30 secs enough i think for them small k16's. But do as you think best.
And congrats on your new purchase, welcome to the club. 

Which early turbo's used Garrett's? Just curious

 

[dparslow]

I always leave mine to idle for 4 - 5 minutes the time it takes to unlock and open gates, garage doors etc. After some "progressive driving" I always take it easy for a couple of miles to let everything cool down anyway.

The engine blower coming on is quite normal, mine usually comes on a few minutes after the car has been parked up and turned off, but only for a few seconds.

Drive and enjoy []

 

[sniper]

I think all turbo cars should be allowed to idle post driving hard - something to do with the oil in the turbine bearings - I think.

Alternatively I just drive off boost for the last 1-2 miles on most journeys.

 

[FLAT-SIXY]

It's just what I was told. I was surprised myself. If they did not use garrett turbo's can anyone out there tell us what the First production 911 turbo's used. [8|]

 

[kennyboy]

I read something years ago that the reason you left it to cool was for the the turbo and it's housing to cool down to the same temperature as the engine block of whatever structure they are attached to.

Otherwise the ultra hot turbo would cool much faster than the rest of the engine and the resultant inconsistent metal contraction could cause weaknesses or cracks in the housing?

Leaving the engine on while the turbo is dormant allows it to cool to the same temp as the rest of the engine so when it's eventually turned off everything contracts at the same rate.

Make sense?

 

[SCOTJC]

discussed in length here!
http://www.porscheclubgbforum.com/tm.asp?m=224345&mpage=1&key=

 

[sawood12]

ORIGINAL: RichardLW

944 turbos have a thermostatic switch which allows pumping oil until the innards have reached a sensible temperature and static oil won't be turned to solid carbon. Even then, I would always let mine stand for a couple of minutes before switching off but you could hear that little pump running for quite a while on a hot day. Presumably tts have the same sort of thing?

The turbo on the 944 is water cooled so the pump is pumping water. I'd be very surprised if this is necessary on 993TT's especially if it's not mentioned in the manual. Not only because modern fully synthetic oils can withstand much higher temps than mineral or semi-sythetic oils but I'm sure the turbo's fitted to the 993's are much better designed than the tat Renault would have fitted to the old Renault 5's. If it really still bothers you I would think it is much better for the car to run the car off-boost for the last few miles of your journey rather than sit on the drive as it's when the turbo is on-boost that the temps get anywhere near the levels that might start to effect the oil.

 

[nathan 1981 930 G50]

The 930, which is the first turbo'd production road car used a KKK unit. I believe the 996tt & 996GT2 also uses KKK's.

The idling is to cool the shaft in the turbo unit, they spin at very high rpm and therefore produce a lot of heat. Although the other comment makes sense too as at idle the turbo will not glow.

When I mentioned to a salesman that I had a 930 he did not have a clue what car I was talking about... Harston OPC.

 

[sawood12]

True, but the turbo only spins at the high speeds when you are driving on-boost. When you are driving off boost the turbo is basically free-weeling in the exhaust gas flow at relatively low RPM as the pressure in the exhaust manifold is not high enough to drive the turbo. The lubricating oil, which is cooled, will still be cirulating in the turbo therefore cooling the turbo. As long as you are not thrashing the car right upto your drive before turning the engine off you will be OK.

 

[nathan 1981 930 G50]

Yes, but my turbocharger cost way too much money for the sake of me pushing a button on my key fob before I remove the key from the ignition [&:]