[matlough]

Just a question really, had a friend a few years ago with a Scooby turbo and after a long/fast run he would always let the engine idle before switch off for 1 min or so.

Having not owned a BMW or (twin) turbo before, do I need to do this with my car?

I guessing not, but thought i would ask.

Thanks

[ShereKhan]

I would have thought you need to do the same as a turbo unit generally has bearings which need to cool down especially after you have "thrashed" the car.

[rjs]

when i had my first turbo car i was told to let it idle before switching the engine off, not for a minute though

[- Paul -]

"I suggest you check out the cooling section of the engine management document. http://www.e90post.com/forums/showthread.php?t=38856 See page 48 component protection at the bottom. The 335 is equiped with an electric water pump which continues to circulate water to the turbos after the engine is shut off."

Found in the thread about letting turbos cool down.

[ironjw]

Originally Posted by 1stnewcar

"I suggest you check out the cooling section of the engine management document. http://www.e90post.com/forums/showthread.php?t=38856 See page 48 component protection at the bottom. The 335 is equiped with an electric water pump which continues to circulate water to the turbos after the engine is shut off."

Found in the thread about letting turbos cool down.

hmmm.. i didnt know that

[jonerik26]

yeah, i thought the same thing when i first got my car... so i would idle it for awhile after every drive... but later found out about the cooling system as well on these cars in this forum......ohh is it nice not to have to worry about letting the car sit for awhile, but then i do let it run though after every hard drive.....

[330cdsport]

I got into the habit of just driving the last minute of my journey at a sensible engine speed (non-boost) - and so did not feel the need for idling when i came to a halt.
I have always tried to care for the turbo in this way - since most of my cars have been chipped as well

[- Paul -]

Direct lift from manual

"Component Protection
• After-running of electric coolant pump =
improved heat dissipation from engine switch off
point. Allows protection of turbochargers by
reduced oil “coking” during heat soak."

"The turbine and the compressor can rotate at speeds of up to 200,000 rpm.
The exhaust inlet temperature can reach a maximum of 1050°C. Because of these high
temperatures, the N54 engine's turbochargers are not only connected with the engine-oil
system but also integrated in the engine-coolant circuit.
It is possible in conjunction with the N54 engine's electric coolant pump even after the
engine has been switched off to dissipate the residual heat from the turbochargers and
thus prevent the lube oil in the bearing housing from overheating."

[dxb335d]

its bit chavvy, but there you go, think you will find it you take it easy for last 2 mile or so and just pull up undo the belt etc then turn off it shoudl be fine, its a modern day turbo engine not like the days of the R5GTT etc where you had soem idiot churnign the tits off it pulls straight up turns the engine off whislt stil rolling.... then after a while it will muller the turbo.

Its not so much the cooling down but the oil from the turbo, you turn off whilst its still spinning then you will starve the turbo of oil..

im sure bmw have got some sort of system that stops that from happening but i wouldnt unduly worry, just take it easy the last coupla miles

[dxb335d]

Originally Posted by 330cdsport

I got into the habit of just driving the last minute of my journey at a sensible engine speed (non-boost) - and so did not feel the need for idling when i came to a halt.
I have always tried to care for the turbo in this way - since most of my cars have been chipped as well

non boost? on a turbo diesel, check the mpg gauge in the instrument cluster, when your doing the last coupla miles of town or village driving, when thats showing low mpg (ie driving into your driveway) then that is boosting, most modern turbo diesels are boosting all of the damn time due to the size of the turbo because the diesel dosent rev past 5k it dosent need a big turbo therefore is always 'on boost' near enough, maybe not full boost but boosting

[ChrisMWard]

A lot of benefits have come from the use of modern fully synthetic oils which can withstand the higher temperatures encountered with turbos.

Even if your turbo hasn't been running on boost for a few minutes the residual heat can destroy the oil. I've seen turbos still glowing red at the end of a race after the car has taken a lap to get back to the pits.

The water cooled turbos have certainley improved reliability no end, also diesel engine exhaust gas temperature is a lot lower than petrols.

I've allways allowed turbos to run down and I guess I allways will, just habit I suppose.

Regards

Chris

[MattOz]

I almost always do the last couple of miles slowly and then if I've been "enjoying" the car during that journey I allow it to idle for a minute before switching it off. You can hear the auxilary water pump working once the car is turned off anyway.

In the past, I've filled the car up with the engine running following an Autobahn blast, just to keep the turbos supplied with oil. No harm doing that, and I've never had a turbo blow yet. Cue both going tits up on me tomorrow! LOL

Matt