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Old 21st October 2020, 11:48   #11
torque2me
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Quote:
Originally Posted by edwardmk View Post
I don't know if it's true, but I was told by someone years ago that you should let a turbo car idle for around thirty seconds after a hard run. Apparently the reason was that some turbos get so hot they boil their lubricating oil if the engine is just switched off. It was way back when I was running a Lancia Delta turbo. So I always did that. That car was totally reliable and I sold it on to my brother in law who subsequently sold it on and then bought a new one back in the 80's ( 'cos he missed it after it was sold lol). He told me he never bothered with what I told him and both cars were fine, so maybe the advice wasn't needed for that model of car.
Very true. The local fitter/engineer/technician who looked after my Aston Martin I had once upon a time told me about the heat issue and they had quite a few disgruntled owners who probably never listened. Turbo re-designs and upgraded oils eventually helped. My 820 Vitesse Sport spewed the waste-gate into the exhaust even though I followed advice re idling. In fact this vehicle would keep the fan going for about 30 sec.

Kev
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Old 21st October 2020, 14:59   #12
SCP440
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A well engineered Turbo engine is not a problem, you only have to see how many Saab's that have done big mileages with little or no trouble and some of those are pushing out big horse power.

The problem is a big turbo on a small engine is putting the cylinder pressures high all the time to give you the performance of a big engine and that with 20k mile oil changes is to much for the poor quality materials that are being used in the construction of these engines.

As has been said the cost of the fuel is often peoples biggest concern but in truth unless you are doing 25k or more a year is often less than the depreciation and servicing costs. Driving a V8 car 8 to 10k a year that just about to does 20mpg with little or no depreciation is a cheaper car to run and the engine should last many years due to it being under stressed.
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Old 22nd October 2020, 20:23   #13
COLVERT
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Originally Posted by macafee2 View Post
I always let the car idle after a long run and particularly if towing, it may even be in the handbook, 2 -3 minutes. I also lift the bonnet to let the heat out if I have been towing. Strangely or sadly no one has ever asked when I'm parked at motorway service with the caravan attached and bonnet up if I am ok, they just walk past.

macafee2
The reason for the tick over bit is to make sure there is oil in the turbo bearings. It's not really to dissipate very much heat though it helps.

Some folk have the engine revving as they switch off. The turbo could be spinning at around 80,000 rpm.--

As the engine stops the oil flow stops too. The turbo then slows down to a halt with NO OIL PRESSURE.

With the engine ticking over for twenty seconds, maybe, the turbo is then spinning very slowly. As the engine stops the turbo is very quick to follow leaving plenty of oil in the bearings for the few seconds it takes for the turbo to stop.

In fact the turbo body with no air flow to help cool it will actually get hotter but not hot enough to damage any components.
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