Turbo cool down question

Walked U · 01-12-2007, 09:46 PM

I saw a question in the Bimmerforums that was kinda interesting.

"I have to let me 05 STi to cool down before shutting it off, but it is oil cooled. If I'm not mistaken the 335i is liquid and oil cooled like the new STi. So do I have to let it cool down or is it ok to shut it off right away."

Now I was wondering the same thing because when I run my car hard. I usually will let it sit for about 3-4 mins before i turn it off.

I guess im just old school like that, since the car doesnt have a turbo timer.

FirstClass · 01-12-2007, 11:36 PM

Why do you need to let the car cool after you're done driving? Its not going to get any hotter while its off and its not going to get much cooler if it isn't moving...

Edit: Nvm, just looked it up. Its a turbo thing.

Walked U · 01-12-2007, 11:46 PM

Oh.. I guess you dont know how turbos and the oil that cools them down work.

The oil that sits in the turbos when you immediately shut down the car is very hot. By the oil circulating in the turbos at a lower temp, this prevents cracks in the turbines. Which keep your turbo alive longer. Thus why people get turbo timers, or sit by their car while its stationary after a spirited drive.

Now my question is that I heard the 335i has a built in turbo timer or circulates cool oil through the turbos when the car is shut down. Wanted to know if that was true or not. So I dont have to get a turbo timer.

wj4 · 01-13-2007, 12:00 AM

Turbo timer is mostly a show mod in my eyes. Modern turbo'd cars are a lot more efficient at cooling down than older ones. I have a turbo timer in My Evo, and most of the time, I don't even use it.

The oil will not cool that much off within 30 seconds to a minute of idling (Avg time people program their turbo timer for). It just makes you look "cool" when you get out of the car while it still runs and have the car turn off a bit later.

If I go on a track, and push my car hard, I will let the car sit while it's on for a good 5-10mins, but this is pushing it VERY HARD, not normal everyday driving where you encounter redlights and/or stay at a consistent low rpm like on the highway.

I used to be paranoid too, when I got my Evo and let the car run for several mins after a normal drive to school, run errands, etc. until I found out that it's not really necessary.

Walked U · 01-13-2007, 12:04 AM

Naw thats what I was asking. "Spirited" driving, as in tracking it or drag striping the car.

I dont let my car sit when i get to work or whatever. But I do let it sit after I drive it very hard.

jmonier · 01-13-2007, 12:08 AM

The coolant (water) pump is electrically driven and will run after the car is shut off. Both oil and coolant go through the turbos and thus the coolant still takes heat out of the turbos even after the car is shut off. So, in effect, there is already a "turbo timer" that works without having to keep the engine running.

Walked U · 01-13-2007, 12:12 AM

Quote:

Originally Posted by jmonier

The coolant (water) pump is electrically driven and will run after the car is shut off. Both oil and coolant go through the turbos and thus the coolant still takes heat out of the turbos even after the car is shut off. So, in effect, there is already a "turbo timer" that works without having to keep the engine running.

Nice thanks a lot jmonier for clearing that up.

Nexus-6 · 01-13-2007, 12:16 AM

You can hear the pumps continuing to run after shut down (as long as the car was brought to normal operating temps for a period of time).

You can only hear them if you're in the garage or someplace relatively quiet but they run for anywhere from 30 seconds to a minute in my experience.

teknochild · 01-13-2007, 01:39 AM

i have a question for you, whats the diffrence between a bunch of oil running through your turbo at 200 degrees and a bunch of oil sitting in your turbo at 200 degrees?

i meen i understand the oil sitting in your turbo is going to get hotter if the turbo is hotter than the oil, but if its circulating its not going to take long for most of the oil to get up to the same temp as your turbo... with the car not moving foward the oils not going to be cooled very much, so id guess after the oil is circulated enough to be the same temp as the turbo, its not going to help anymore

mayno · 01-13-2007, 01:57 AM

http://autospeed.drive.com.au/A_0145/cms/article.html

"You're Mad If You Don't Have a Turbo-Timer Fitted to Your Turbocar..."

Basically, a turbo timer just an elaborate egg timer with an output relay - and a lucrative price.

The idea of these timers is to keep the engine running for a pre-determined length of time after the ignition switch has been turned off. This enables the turbo to cool down more gradually and prevent oil choking up within its core.

This makes sound engineering sense, but the concept of not being on turbo boost just before you switch off seems more logical. Take the effort to drive the car gently before shutting off, and maybe let it run for another 30 seconds while you put your sunnies back in the glove-box and put the steering wheel lock on. It'll save you money, possible difficulties with alarm interfaces and, above all, it won't give car thieves an easily-accessible bypass to your vehicle's ignition system.

MBrown1003 · 01-13-2007, 01:18 PM

Quote:

Originally Posted by teknochild

i have a question for you, whats the diffrence between a bunch of oil running through your turbo at 200 degrees and a bunch of oil sitting in your turbo at 200 degrees?

i meen i understand the oil sitting in your turbo is going to get hotter if the turbo is hotter than the oil, but if its circulating its not going to take long for most of the oil to get up to the same temp as your turbo... with the car not moving foward the oils not going to be cooled very much, so id guess after the oil is circulated enough to be the same temp as the turbo, its not going to help anymore

From what I know of high-performance BMW engines, they have very large oil capacities, so that you've got an awful lot of oil to take the thermal load from the turbo housings. My thinking is that while the oil gets a little hotter, it will still be far cooler than the turbo housing, especially with both oil and water circulating.

I CAN'T WAIT TO SEE / HEAR / TRY ALL THIS! My car should have arrived in NY two days ago, and I'm hoping to take delivery in the next 4 or 5 days.

khafner · 01-13-2007, 02:26 PM

Turbo's get there power from the exhaust heat. This is very hot. Easily greater than 1500F. When you suddenly turn off an engine with a turbo (especially if you have been driving it hard) all this heat has to be dissipated. You can easily fry your oil. Letting it idle circulates the oil ( and water in a bmw). With low boost this heat is quickly lost. Your oil, engine and turbo will last much longer if you practice letting the turbo run at idle for a short period of time before turning the engine off. When I was really into this stuff we would let things idle till we could no longer see the exhaust housings glowing red. Unfortunately that is not easy to check on an automobile.

teknochild · 01-13-2007, 03:58 PM

Quote:

Originally Posted by MBrown1003

From what I know of high-performance BMW engines, they have very large oil capacities, so that you've got an awful lot of oil to take the thermal load from the turbo housings. My thinking is that while the oil gets a little hotter, it will still be far cooler than the turbo housing, especially with both oil and water circulating.

I CAN'T WAIT TO SEE / HEAR / TRY ALL THIS! My car should have arrived in NY two days ago, and I'm hoping to take delivery in the next 4 or 5 days.

yea thats right it has something massive like 8 quarts or so

boggysv · 01-14-2007, 08:19 AM

Quote:

Originally Posted by maynardc

This makes sound engineering sense, but the concept of not being on turbo boost just before you switch off seems more logical. Take the effort to drive the car gently before shutting off, and maybe let it run for another 30 seconds while you put your sunnies back in the glove-box and put the steering wheel lock on.

Not to disagree, but this reminds me of a story of a friend.

Apparently he was flogging his car (stage3 s4) quite hard for some time, and at a point, had to use the bathroom urgently. As he drove into the highway's restroom to relieve himself, his gf switch the ignition off without hesitation. They came back on a tow truck.

That doesnt warrant a turbo timer, but it sure is food for thought.

Driver72 · 01-14-2007, 10:38 AM

Quote:

Originally Posted by boggysv

Not to disagree, but this reminds me of a story of a friend.

Apparently he was flogging his car (stage3 s4) quite hard for some time, and at a point, had to use the bathroom urgently. As he drove into the highway's restroom to relieve himself, his gf switch the ignition off without hesitation. They came back on a tow truck.

That doesnt warrant a turbo timer, but it sure is food for thought.

And more than likely he would of been leaving on a tow truck if she was to of left the car running too. The flogging of the car for some time and the fact is was the TT S4 was the issue.

I've owned a half dozen turbocharged cars, the first back in the late 80's before most even had intercoolers, and WAY before all the electronic gizmos they have now, with less precise engine specs, not as good oil, etc etc.
Sure letting the car "cool down" immediately after running it hard was wise and probably necessary.

Now, I still wouldn't track the car or be flogging the hell out of it and come to an immediate stop and turn the car off. But I wouldn't do that with a naturally aspirated car either.

Just be smart...if you are flogging the car hard and are almost at your destination, drive normally for the last mile or two to let the turbo(s) cool a bit.
If you are at a track, drive it back to the pits slowly keeping out of boost.

There are millions of turbocharged cars in the world, do you think everyone who has one that flogs the car...or drives on the autobahn for hundreds of miles at excessive speed, pulls off and lets there cars sit for 5+ minutes before turning them off??

Ask the techs at a dealer, "how often do turbocharged cars come in with turbo failures?" and then, "how many of them were caused because it was driven hard one day and not given an extended cool down period before turning the engine off?"

musc · 01-14-2007, 12:05 PM

Quote:

Originally Posted by Driver72

Just be smart...if you are flogging the car hard and are almost at your destination, drive normally for the last mile or two to let the turbo(s) cool a bit.
If you are at a track, drive it back to the pits slowly keeping out of boost.

Simple advice and more than sufficient 99% of the time.

Shawn_speed · 01-24-2007, 04:27 PM

Good points have been made here. So we interrupt your normally scheduled programming for a cooking lesson. I season my wok after every use. I never wash it with detergent or use scouring pads in it. Just warm some water in it, wipe the water around while on the burner, rinse, dry and put it back on the burner and set on high. Then I put a little oil in it and coat the whole thing using paper towel. The oil will heat, smoke and then coke and harden. This is called seasoning. If you examine any good cook's wok, it'll have a hard, black coating in the bottom.

Essentially this process can happen in a turbo. Stationary oil in the turbo will overheat after the car is turned off through a process called heat soak. The oil will coke and harden. It is akin to clogged arteries. The turbo can turn as fast as 200,000 rpm; if the oil supply to the turbo’s bearings is impeded in any way, they'll be ruined real quick.

Hence the old turbo timers and the electric coolant pump in the 335 to circulate coolant after the engine is shut off as well as the properties of the newer synthetic motor oils.

Shawn
Phoenix

SROC3 · 01-24-2007, 05:20 PM

Quote:

Originally Posted by jmonier

The coolant (water) pump is electrically driven and will run after the car is shut off. Both oil and coolant go through the turbos and thus the coolant still takes heat out of the turbos even after the car is shut off. So, in effect, there is already a "turbo timer" that works without having to keep the engine running.

+1 - you can actually hear it after the car shuts off. Its an electric pump buzzing in the background. But I still would make sure that i cool off the car after a HARD run. 5 min of idling should suffice.

SpiralOut · 02-17-2007, 07:12 PM

I realize this is a kindof old thread... but I have a Q.

I don't hear the turbo/oil cooler running any more when I turn off my car? Even when the engine is at full temp (few ticks above 210). I just got the car a week ago ago and for the first few days I heard it running after I shut the car off... it was like a very faint pump sound, but the last 3 or 4 days I haven't heard it.

Should I be worried and go get this checked out or does it just not come on all the time? Not sure if it matters, but it's sorta cold here now.... 20's at night and maybe low 40's during the day.

jmonier · 02-17-2007, 07:22 PM

Quote:

Originally Posted by ismithnc

I realize this is a kindof old thread... but I have a Q.

I don't hear the turbo/oil cooler running any more when I turn off my car? Even when the engine is at full temp (few ticks above 210). I just got the car a week ago ago and for the first few days I heard it running after I shut the car off... it was like a very faint pump sound, but the last 3 or 4 days I haven't heard it.

Should I be worried and go get this checked out or does it just not come on all the time? Not sure if it matters, but it's sorta cold here now.... 20's at night and maybe low 40's during the day.

If you push the REST button on the Climate Control, the pump has to run to keep the car warm. If it appears that it isn't running then you should have it checked out. It may just be that at the temps you mention the pump only has to run for a very short period of time and thus you don't notice it. If you have a real doubt, you should have it checked out though, since it could result in turbo damage.

SpiralOut · 02-17-2007, 08:10 PM

Yep, I just went out and started and then turned off car, then hit the rest button and I hear the pump come on and run. So the pump works... it just doesn't come on after the car goes off anymore.

I'll call my service dept and see what they say about this. I'll just idle it for a few minutes before shut off till I get an answer.

retrodrive · 02-17-2007, 08:37 PM

Not sure what oil bmw uses but if it is fully synthetic, you have nothing to worry about. If it is not synthetic, change it.

01-12-2007, 09:46 PM	#1
Walked U Brigadier General 188 Rep 3,125 Posts Drives: Too many to list Join Date: Nov 2006 Location: USA iTrader: (5)	Turbo cool down question I saw a question in the Bimmerforums that was kinda interesting. "I have to let me 05 STi to cool down before shutting it off, but it is oil cooled. If I'm not mistaken the 335i is liquid and oil cooled like the new STi. So do I have to let it cool down or is it ok to shut it off right away." Now I was wondering the same thing because when I run my car hard. I usually will let it sit for about 3-4 mins before i turn it off. I guess im just old school like that, since the car doesnt have a turbo timer. __________________ Previous - E90 335i, E82 135i, E89 Z4 3.5SI, Range Rover S/C, Ultra White RCF, Maserati Granturismo Current Lexus: SMG LC500 performance package Porsche:1973 911E Ferrari 575 SA, 458 Italia
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01-12-2007, 11:46 PM	#3
Walked U Brigadier General 188 Rep 3,125 Posts Drives: Too many to list Join Date: Nov 2006 Location: USA iTrader: (5)	Oh.. I guess you dont know how turbos and the oil that cools them down work. The oil that sits in the turbos when you immediately shut down the car is very hot. By the oil circulating in the turbos at a lower temp, this prevents cracks in the turbines. Which keep your turbo alive longer. Thus why people get turbo timers, or sit by their car while its stationary after a spirited drive. Now my question is that I heard the 335i has a built in turbo timer or circulates cool oil through the turbos when the car is shut down. Wanted to know if that was true or not. So I dont have to get a turbo timer. __________________ Previous - E90 335i, E82 135i, E89 Z4 3.5SI, Range Rover S/C, Ultra White RCF, Maserati Granturismo Current Lexus: SMG LC500 performance package Porsche:1973 911E Ferrari 575 SA, 458 Italia
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01-13-2007, 12:00 AM	#4
wj4 Major General 358 Rep 7,719 Posts Drives: E90 manual 335i Join Date: Nov 2006 Location: Burbank, CA iTrader: (8)	Turbo timer is mostly a show mod in my eyes. Modern turbo'd cars are a lot more efficient at cooling down than older ones. I have a turbo timer in My Evo, and most of the time, I don't even use it. The oil will not cool that much off within 30 seconds to a minute of idling (Avg time people program their turbo timer for). It just makes you look "cool" when you get out of the car while it still runs and have the car turn off a bit later. If I go on a track, and push my car hard, I will let the car sit while it's on for a good 5-10mins, but this is pushing it VERY HARD, not normal everyday driving where you encounter redlights and/or stay at a consistent low rpm like on the highway. I used to be paranoid too, when I got my Evo and let the car run for several mins after a normal drive to school, run errands, etc. until I found out that it's not really necessary.
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01-13-2007, 12:04 AM	#5
Walked U Brigadier General 188 Rep 3,125 Posts Drives: Too many to list Join Date: Nov 2006 Location: USA iTrader: (5)	Naw thats what I was asking. "Spirited" driving, as in tracking it or drag striping the car. I dont let my car sit when i get to work or whatever. But I do let it sit after I drive it very hard. __________________ Previous - E90 335i, E82 135i, E89 Z4 3.5SI, Range Rover S/C, Ultra White RCF, Maserati Granturismo Current Lexus: SMG LC500 performance package Porsche:1973 911E Ferrari 575 SA, 458 Italia
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01-13-2007, 12:08 AM	#6
jmonier Captain 11 Rep 812 Posts Drives: 2007 335i E92, 2002 325i Join Date: Aug 2006 Location: Torrance, CA iTrader: (0)	The coolant (water) pump is electrically driven and will run after the car is shut off. Both oil and coolant go through the turbos and thus the coolant still takes heat out of the turbos even after the car is shut off. So, in effect, there is already a "turbo timer" that works without having to keep the engine running.
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01-13-2007, 12:16 AM	#8
Nexus-6 Private First Class 11 Rep 170 Posts Drives: '07 BMW 335i Join Date: Dec 2006 Location: Wherever there is hockey iTrader: (1) Garage List 2007 335i [0.00]	You can hear the pumps continuing to run after shut down (as long as the car was brought to normal operating temps for a period of time). You can only hear them if you're in the garage or someplace relatively quiet but they run for anywhere from 30 seconds to a minute in my experience.
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01-13-2007, 01:39 AM	#9
teknochild Your resident 4um troll 141 Rep 2,020 Posts Drives: 335 coupe Join Date: Dec 2006 Location: fl iTrader: (0)	i have a question for you, whats the diffrence between a bunch of oil running through your turbo at 200 degrees and a bunch of oil sitting in your turbo at 200 degrees? i meen i understand the oil sitting in your turbo is going to get hotter if the turbo is hotter than the oil, but if its circulating its not going to take long for most of the oil to get up to the same temp as your turbo... with the car not moving foward the oils not going to be cooled very much, so id guess after the oil is circulated enough to be the same temp as the turbo, its not going to help anymore __________________ RAWRrrrr
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01-13-2007, 01:57 AM	#10
mayno Captain 73 Rep 613 Posts Drives: 2007 335i / 2018 BMW 430i Conv Join Date: Dec 2006 Location: So Cal iTrader: (0)	save your money! http://autospeed.drive.com.au/A_0145/cms/article.html "You're Mad If You Don't Have a Turbo-Timer Fitted to Your Turbocar..." Basically, a turbo timer just an elaborate egg timer with an output relay - and a lucrative price. The idea of these timers is to keep the engine running for a pre-determined length of time after the ignition switch has been turned off. This enables the turbo to cool down more gradually and prevent oil choking up within its core. This makes sound engineering sense, but the concept of not being on turbo boost just before you switch off seems more logical. Take the effort to drive the car gently before shutting off, and maybe let it run for another 30 seconds while you put your sunnies back in the glove-box and put the steering wheel lock on. It'll save you money, possible difficulties with alarm interfaces and, above all, it won't give car thieves an easily-accessible bypass to your vehicle's ignition system.
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01-13-2007, 02:26 PM	#12
khafner Private First Class 6 Rep 123 Posts Drives: e90 330i Join Date: Dec 2006 Location: fulton, ny iTrader: (0)	turbo shutdown Turbo's get there power from the exhaust heat. This is very hot. Easily greater than 1500F. When you suddenly turn off an engine with a turbo (especially if you have been driving it hard) all this heat has to be dissipated. You can easily fry your oil. Letting it idle circulates the oil ( and water in a bmw). With low boost this heat is quickly lost. Your oil, engine and turbo will last much longer if you practice letting the turbo run at idle for a short period of time before turning the engine off. When I was really into this stuff we would let things idle till we could no longer see the exhaust housings glowing red. Unfortunately that is not easy to check on an automobile.
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01-24-2007, 04:27 PM	#17
Shawn_speed Private First Class 7 Rep 173 Posts Drives: e90 335i 6Sp. Join Date: Jul 2006 Location: Phoenix iTrader: (2)	Good points have been made here. So we interrupt your normally scheduled programming for a cooking lesson. I season my wok after every use. I never wash it with detergent or use scouring pads in it. Just warm some water in it, wipe the water around while on the burner, rinse, dry and put it back on the burner and set on high. Then I put a little oil in it and coat the whole thing using paper towel. The oil will heat, smoke and then coke and harden. This is called seasoning. If you examine any good cook's wok, it'll have a hard, black coating in the bottom. Essentially this process can happen in a turbo. Stationary oil in the turbo will overheat after the car is turned off through a process called heat soak. The oil will coke and harden. It is akin to clogged arteries. The turbo can turn as fast as 200,000 rpm; if the oil supply to the turbo’s bearings is impeded in any way, they'll be ruined real quick. Hence the old turbo timers and the electric coolant pump in the 335 to circulate coolant after the engine is shut off as well as the properties of the newer synthetic motor oils. Shawn Phoenix
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02-17-2007, 07:12 PM	#19
SpiralOut Captain 165 Rep 881 Posts Drives: 2022 X5Mc Join Date: Nov 2006 Location: NC iTrader: (11)	I realize this is a kindof old thread... but I have a Q. I don't hear the turbo/oil cooler running any more when I turn off my car? Even when the engine is at full temp (few ticks above 210). I just got the car a week ago ago and for the first few days I heard it running after I shut the car off... it was like a very faint pump sound, but the last 3 or 4 days I haven't heard it. Should I be worried and go get this checked out or does it just not come on all the time? Not sure if it matters, but it's sorta cold here now.... 20's at night and maybe low 40's during the day.
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02-17-2007, 08:10 PM	#21
SpiralOut Captain 165 Rep 881 Posts Drives: 2022 X5Mc Join Date: Nov 2006 Location: NC iTrader: (11)	Yep, I just went out and started and then turned off car, then hit the rest button and I hear the pump come on and run. So the pump works... it just doesn't come on after the car goes off anymore. I'll call my service dept and see what they say about this. I'll just idle it for a few minutes before shut off till I get an answer.
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02-17-2007, 08:37 PM	#22
retrodrive Lieutenant Colonel 152 Rep 1,938 Posts Drives: 335i Join Date: Jan 2007 Location: Irvine, CA iTrader: (8)	Not sure what oil bmw uses but if it is fully synthetic, you have nothing to worry about. If it is not synthetic, change it.
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