Team-BHP - Do all Turbos require idling before shut-off?

The recommendation to run the engine is really for fast runs where the turbo has generated a lot of heat. Idling allows the turbo to cool gradually using oil circulation to dissipate the heat else the bearings will eventually seize.

In town, it should be okay unless you have been doing a lot of fast drags as the turbo has not had to do too much work. My commute ends with a quick sprint on the highway. Merely driving in and doing a slow 15 km/h in the campus for 2 min + 1 min idling suffices

I have a very poor understanding of this - I have read that when you suddenly kill the engine while the turbo charger is spinning - it leads to coking. Doesnt viscosity of the oil have something to do with this?

To clarify - I did not mean coming to a halt from speed on a signal and killing the engine instantly. What I meant is that one need not follow the 1 minute guideline on a hot engine (when you know that you have stopped for a short time).
My understanding of a turbo and the requirement to idle before killing the engine is so that oil can drain back into the sump - excess oil (left behind if the engine is killed immediately after stopping) in the turbo would thicken as the engine cools down and could damage the turbo on the next cold start. The reference to viscosity was with this understanding.
Please correct me if I'm wrong.

I agree with Ajmat here, if you start-off at full throttle and Stop after a hard run, you risk heat soak and oil coking on the turbo bearings. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo’s center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking.

Driving sedately, negates the need for idling even under traffic lights stop/start.

The start of lubrication in Turbo's is similar to engine lubrication on cold start, takes few seconds and you cannot help the initial gap.

Remember the turbo runs under scorching temperatures, manifold temperatures of intercooled setups are typically 40 - 54 degrees C, while non-intercooled values can reach from 80-150 degrees C and therefore you cannot bring down these extreme temperatures to normal, in few seconds/ minutes.

They are designed to handle these temperatures under "normal running conditions".

Quote:

Originally Posted by tsk1979 (Post 944559)

viper its nothing to do with viscosity.
when engine is shut off, the oil pump stops and no oil is sent to turbo.
So if you were at revs where turbo was spinning fast, when you switch off your turbo will run dry for more time.

If you idle you allow turbo to come to a slower speed. So when you shut off engine, oil supply stops and slowly turbo comes back to 0.
At full boost I am told turbo's can touch 20,000rpm

so i guess it is for both cooling and slowing the turbo. Idling is necessary. A full auto turbo timer takes care of everything.

I think you missed a zero. It should be 1.5 to 2 lak rpms.

A lot of the replies have correct info, but the short of it is.. if at all possible, idle the car for 60 seconds. In the end, it will not hurt anything, but you and you turbo are playing on the safe side.

There is a simple explanation for idling before and after drive in turbo engine[ older once]. Earlier turbos, used a Hydromatic bearing, that is the spinning shaft is maintain in the center of it's casing by a think layer of oil which is provided by the oil pump, since the turbo spins at very high rpm, and if the engine is accelerated before this thin film is formed than there may be turbo failure. So it is advisable to idle [this was the main reason].
Newer cars have ball baring turbos, so only heat is a concern that to if the engine is pushed hard. so idling is not required in modern cars[which have ball baring turbos].

Its only us owners who take care about idling before acceleration and shut-off, do you guys think the service station mechanics, valet parking guys take care? just yesterday i gave my car to the valet at a restaurant who just thought my car was made for ripping & came driving from the area where he parked in 1st gear only, mind you he was fast. :Frustrati

We cant control these guys, just a thought.

Today i came across an ad in a auto magazine about a company which manufactures turbo timers.
It is basically a device connected to your engine which makes your engine run for some time ( set by you) after you switch off the engine and remove the key.
Is it safe to connect such a aftermarket device?
It sounds really convinient for people like me who make short trips all round the day and its not possible to turbo-idle all the time.

gurus..kindly advice..

If it is true (& really work), then it is a fantastic device. If you are having a turbocharged vehicle defiantly go for it.
Actually turbo idling is a matter of habit & mental peace. Many times even after getting habitual, we shut off the engine immediately at destination because mind set is towards some different matter. In long life this (may) shows bad effects on turbo charger.

Quote:

Originally Posted by headers (Post 425595)

Its better to switch off then rather than "Rev the car and switch off" like some truckwallas do it:confused:

This is there (truckwallas) bad habit (since the time of non turbo engines ) to charge the battery and this habit [FONT=&quot]Continue from truck driver (ustaad) to cleaner (future driver) as a guru mantra.[/FONT]

1 question.
If the engine is to be idled solely for the oil pump to be operating, so that the oil can be pumped into the turbo after shut down, isn't it possible to have an alternate oil pump that is battery operated.
That way when you stop, rather than idling the engine or installing a turbo timer [which means you can't engage the gear], the alternate oil pump kicks in for the required amount of time.
This can also be set up to start via remote [rather than having the entire engine fire up], so you don't have to idle before you start?