Turbos and Stop/Start Technology

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Sun 31 Jul 2011 20:08
Turbos and Stop/Start Technology - V4 Heaven

Hi all,

The general school of thought for turbos (petrol or diesel) is to not turn the engine off immediately after a trip out etc.

With stop/start technology, would the engine be cut prematurely thereby stopping oil flow to the turbo? Long term, would stop/start harm the turbo?

Just wondering.

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Sun 31 Jul 2011 21:09
Turbos and Stop/Start Technology - unthrottled

No.

Do you worry about the coolant boiling in the water passages near the exhaust ports on a naturally aspirated engine when you switch it off after a hard run? Of course not!

The idle before switching off really only applies to switching off immediately after heavy use on an oil-cooled turbo.

Water-cooled turbos are generally OK because the heat of vaporisation of water is massive, so when the water in the turbo boils it pulls out sufficient heat from the turbo to stop the oil coking.

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Mon 1 Aug 2011 11:11
Turbos and Stop/Start Technology - V4 Heaven

I am concerned as to whether the turbo is being starved of oil regularly due to manufacturer's latest sales gimmick - stop/start technology.

Edited by V4 Heaven on 01/08/2011 at 11:14

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Sun 31 Jul 2011 22:57
Turbos and Stop/Start Technology - Avant

How many of us know whether our turbos are oil-cooled or water-cooled? Any technical expert care to enlighten us?

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Mon 1 Aug 2011 00:17
Turbos and Stop/Start Technology - Roly93

I have a stop start diesel Audi, and I have been wondering the very same thing.

Apparently the ECU will take into account if the engine is excessively hot and will simmer the engine before going into start-stop mode.

I thought the turbo in most cars we oil cooled, is this not the case ?

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Mon 1 Aug 2011 02:39
Turbos and Stop/Start Technology - unthrottled

Oil lubricated. Most turbos now must surely be watercooled.

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Mon 1 Aug 2011 09:01
Turbos and Stop/Start Technology - jc2

Surely most use of stop/start will be around town when the turbo is not very hot.Turbos only get very hot at max speed/max power.

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Mon 1 Aug 2011 09:25
Turbos and Stop/Start Technology - daveyjp

The stop start system is also not the same as turning the car off at the key.

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Tue 2 Aug 2011 12:58
Turbos and Stop/Start Technology - gordonbennet

A driver concerned enough to care about the turbo would probably turn off stopstart unless in his/her opinion the turbo was cool enough to cope, fine in town work, but you wouldn't want it to shut down the second you reach the roundabout queue after a 50 mile blast.

Just as the same driver would leave the engine to tick over for a bit, and not thrash the living daylights out of it till the engine was warm.

Common sense mechanical sympathy.

Edited by gordonbennet on 02/08/2011 at 12:58

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Tue 2 Aug 2011 14:47
Turbos and Stop/Start Technology - unthrottled

Common sense mechanical sympathy.

I really don't think so. This was once true but now is all but irrelevant. A combination of water cooling and fuel cut off during overrun mean that the turbo should not have a problem with coking.

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Thu 4 Aug 2011 12:06
Turbos and Stop/Start Technology - barney100

I would not want a car with stop start, it seems just another thing to go wrong and I will turn the car off if needs be. It must put a strain on the starter motor and electrics too.

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Thu 4 Aug 2011 12:43
Turbos and Stop/Start Technology - unthrottled

Well, the starter motor is beefed up by the carmakers.

Interestingly, the savings aren't huge. Renault reckon that it saves 3% on the entire NEDC which contains quite a few short stretches of idling.

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Thu 4 Aug 2011 14:36
Turbos and Stop/Start Technology - jamie745

I could imagine that stop start thing could pose problems as the car gets older, might take longer to react or go wrong entirely. Theres some things which we dont need, frankly. Parking sensors were a good idea, albiet only needed due to carmakers consistently making their cars harder to see out of. Sat Nav was a good idea. The rear view camera thing is a good idea. But do we really need a car which switches itself off?

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Thu 4 Aug 2011 14:38
Turbos and Stop/Start Technology - daveyjp

The starter motor isn't used to restart the engine on modern stop/start technology vehicles. They have a small generator and a battery which is charged during braking.

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Thu 4 Aug 2011 16:13
Turbos and Stop/Start Technology - unthrottled

You mean the ISG? True, but I was justtrying to KISS!

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