TODAY's TURBO-Do You Idle Before Shutdown

jason510

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I've been reading up on this topic and there doesn't seem to be a consensus. That is letting your engine idle for a minute or two to help cool the oil in the turbo before shutting down.

I know that turbos have evolved from the early days, but there doesn't seem to be a consensus on TODAY's TURBO's. One part of me says to treat my car well with scheduled maintenance and not over think it, while the other knows I plan on having this car for a while and we know about an ounce of prevention.

What are your thoughts and practices?
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I had the same thought, so whenever I park I leave my car running as I check my phone and maybe send a text, if you have tunerview i know that I usually stay off of the turbo and it doesn’t actually spool up with casual driving but if I aggressively drive it then I let it idle to cycle all the fluids anyways
 

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I've been reading up on this topic and there doesn't seem to be a consensus. That is letting your engine idle for a minute or two to help cool the oil in the turbo before shutting down.

I know that turbos have evolved from the early days, but there doesn't seem to be a consensus on TODAY's TURBO's. One part of me says to treat my car well with scheduled maintenance and not over think it, while the other knows I plan on having this car for a while and we know about an ounce of prevention.

What are your thoughts and practices?
I would say if you were driving hard on the track on a hot day for extended periods, than I would probably do a cool down before shutting off. For normal driving, it's not really necessary. Todays synthetics are pretty tough, not like yesterdays motor oil. I sent a sample from my last oil change, 7K miles of extremely hard driving in various conditions, and my oil was still in good condition (I could have waited a couple thousand more miles before changing)
 

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Let it idle a min at least, it’s not about cooling the oil, it’s letting the oil drain from the turbo back into the oil pan...
 

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I guess idle would reduce the exhaust temps hitting the turbo. Don't know the running exhaust gas temps vs. idle.

It probably doesn't reduce oil temps much. A lot more metal in the block vs. turbo that would stay hot. Have to idle for a good bit to cool that down..
 


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Because of the design of the "exhaust manifold" we don't have to be as careful as we used to be about "turbo cooling". If you drive carefully into your driveway or a parking lot, then collect yourself before you turn the car off. You've probably done enough to protect the turbo. On the other hand if you do a hard pull, slam to a stop, and turn the motor off, your asking for trouble.
 

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i usually let it idle for 1 min possibly 2 after driving it, when the old lady drives it we all know she aint idling the car for more than a few seconds so who knows if its even worth my time
 

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Sorry, but there is some really bad info in this thread. Unless you are driving your car really hard right before parking it, just shut it off. Ever since the advent of water cooled turbos, you no longer need to idle before shutting down. Wonder why you rarely see people w/ turbo timers?... water cooled turbos are why.
 
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jason510

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I'm glad I asked the question because a simple internet search yields the same responses that are reflected on this thread so far.

Some car pros say it's still a good idea while others say that's bad information. I guess as time goes on and these engines begin to age over the 3+ years they've been around, we'll know more.
 

Design

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The last post is correct, you do not need to post-idle your engine, and I am saying this as an engineer for a turbocharger company. On a water-cooled center-housing turbo (all modern gasoline turbos), the cooolant continues to circulate a bit even (thermo-siphoning) after the engine shuts down. Besides, idling is rough on an engine for a number of reasons, and while the oil temp will drop during idling, the underhood temps rise. The underhood temps can be an isssue for the longevity of all the rubber and plastic components in the engine compartment, as well as the battery. The best way to cool off the turbocharger after some really hard driving is to just drive easy at moderate speeds. This gets a good flow of fresh air flowing through the engine compartment. If you are at a competitive event, open the hood after your run.

Dave
 

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Tracked my car Sunday and I would let it idle for about a minute before shutting off to help cool down. I was also surprised the car let me shut it off without putting on the parking brake. I was pleasantly surprised. :D But aside from tracking, with normal driving, I never really idle.
 

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I think if you drive you car hard and your IAT's are up there, idling before shutdown makes sense. As far as normal driving, if it needed to be idled before shutoff, don't you think Honda would have mentioned it in the owner's manual to cover their ass?
 
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jason510

jason510

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The last post is correct, you do not need to post-idle your engine, and I am saying this as an engineer for a turbocharger company. On a water-cooled center-housing turbo (all modern gasoline turbos), the cooolant continues to circulate a bit even (thermo-siphoning) after the engine shuts down. Besides, idling is rough on an engine for a number of reasons, and while the oil temp will drop during idling, the underhood temps rise. The underhood temps can be an isssue for the longevity of all the rubber and plastic components in the engine compartment, as well as the battery. The best way to cool off the turbocharger after some really hard driving is to just drive easy at moderate speeds. This gets a good flow of fresh air flowing through the engine compartment. If you are at a competitive event, open the hood after your run.

Dave
Like I've mentioned a few times now, there is a contradictory argument. I'm not saying either is right, but the one consistent idea seems to be that after hard driving, drive the car easy for a bit before shutting down. I've never heard idling causing rubber, plastic and battery degradation, but living in SoCal, idling for a minute at a time is commonplace so I'm wondering how that affects overall engine life. Either way, I appreciate everyone's input.

https://www.team-bhp.com/tech-stuff/idling-rule-turbo-charged-cars

https://www.quora.com/Why-should-a-turbo-charged-engine-run-idle-for-some-time-before-stopping-it
 

Design

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There are going to be rare circumstances where 30-60 seconds of idling may help. But we're usually talking about high output, modded powertrains operating well outside factory parameters after a hot lap.

Unless specifically called out in the owner's manual, which is rare, there's honestly no need to to do it on stock configurations.

EDIT: Remember with factory water cooled turbos, they are engineered to slowly dissipate heat even after the car is turned off (convection). This has been the industry norm for nearly two decades. :cool:
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