How long do you coo; dpwn your valves?

[twin plugged targa]

Just took the 911T for a spin around the block in temps of 6 deg. Celcius (she loved it!).
After some spirited driving I cooled her down for the last mile or so at low revs and then for a minute or so parking in the driveway/garage.
Is this enough?
I would think sitting at idle stopped is also bad after a hard run as the car would continue to heat up?
cool down period would vary depending on how hot she gets and ambient temps.
Do you all have a 'rule of thumb?'
thanks
Ben

[initial]

I know cooling down after a morning run is beneficial, but for a 911?!?!?

Do the pros and cons of stretching also apply here?!

[DanielDudley]

I don't worry so much about it as I do with a turbo. I wouldn't idle it though. Idling a turbo keeps the oil flowing at idle with relatively little exhaust flow to heat the manifold. I don't see the purpose in a car that requires movement to get proper airflow.

Interesting question. I would be curious to see what others say.

[Gogar]

I wait a minute or so before stopping the car when I park, but more to get more oil out into the tank, as opposed to in the engine. Less startup smoke, IMO. I could be imagining things though.

[RSTarga]

I can't imagine why it would matter, I just turn the key off.

[ossiblue]

In my motorcycle riding days, if the baffles had been removed from the exhaust, we'd plug the end of the exhaust pipe after riding to prevent damage to the valves. I've seen race cars, with short, straight exhausts also having this done. On a street 911 though, I've never even thought about it. Plenty of heat retention built into the engine/exhaust already. I'm certainly no expert but I've never heard of valve damage from failure to use a cool down procedure after a drive--even a spirited one--in a street car. Just turn off the engine.

[Canada Kev]

I wouldn't bother idling afterward, though I usually run the car pretty gently the last few blocks before home.

[dshepp806]

"cooling down" would be WITH movement (air) and conservative driving for a bit after sprited stuff or stop and go traffic,...sometimes, I'll even put some extra cooling miles on should the temps be upward due to traffic hangs and stuuf,...before parking. I usually do this during the summer heat season......I have removed the rear wiper and now use this console switch to manually engage the aux (front) cooler fan when "I" want to.

I always let her idle for about 15-25 seconds seconds before turning her off.

HABITS (and protocol, I'd guess)!!!!!!!!

Best,

Doyle

[aadrew10]

Okay guys,

I will finally tell you my secret that will keep my engine running forever. I always live by hills. This way, after a drive, I drive to the top. Then, I idle for 25 seconds. Then, I begin to drive down the hill. After I reach 10 MPH, I turn the engine off and coast down the hill and into my driveway.

Be careful not to turn the key all the way off because you won't be able to steer! I had an incident with my neighbor's trash can because of this!

I know this works because I have not had any engine trouble for the past 1845 miles that I have driven after having the engine apart.

Cheers!

[dshepp806]

If it's a beasty summer down South, I'll sometimes open the engine hatch for a while.

(hehe)

Doyle

[Dantilla]

I do the opposite. A quick blip of the throttle for a few seconds before shut-down to give the cylinders a blast of cooling air.

Used to have a Turbo, and that's different. I have a long hill down towards my house. I'd coast down the hill, and use very small throttle inputs to get the rest of the way to the garage so the turbo is spooled down before shut-down.

[safe]

In such low temperatures the engine will have no problem with heat. Just turn it off.

After track duty I drive a cool down lap, mostly for the brakes, otherwise I just turn the car off.

[dshepp806]

I stay away from loading the cylinders with gas from a blip.

No doubt, in the winter time, the outside air is your "cooling" friend.

Best,

Doyle

[skinnerd]

As long as you don't have a turbo that you've been running really hard prior to shutdown.....it's a waste of time and fuel to idle your car thinking you're cooling it down before shutoff.

I'm mean really....think about it.
Air cooled, water cooled, it doesn't matter.

If this was really necessary you'd see all the major automakers recommending this practice.....including Porsche.
None do.
Simple as that.

This is the last thing you need to worry about.

[KNS]

Air cooled aircraft engines have a cool down period to bring down cylinder head temps before shutdown. I don't think it so crazy to do the same for a Porsche on a hot day...

[dshepp806]

Originally Posted by KNS

Air cooled aircraft engines have a cool down period to bring down cylinder head temps before shutdown. I don't think it so crazy to do the same for a Porsche on a hot day...

Bingo!

Doyle

[Brando]

Originally Posted by aadrew10

... Be careful not to turn the key all the way off because you won't be able to steer! I had an incident with my neighbor's trash can because of this! ...

Wow! You gotta share this one...

[RoninLB]

if it's hot I'll open hood and throw a 2' x 2' fan angled on a 2x4 under engine before shutdown and keep it running for awhile after

i figure top cylinder area is most likely to coke oil and unburnt gas on cyl and piston

[aadrew10]

Originally Posted by Brando

Wow! You gotta share this one...

It's pretty simple really. Doing my cool down coast, I had the key off, and tried to turn, and couldn't. The girls next door had a bunch of their cheer friends over from Poly out on their front porch. CRASH! goes the trashcan as I slam on the brakes. Of course, by this time I have lost all my momentum avoiding the accident, and now like a double doofus, I'm sitting a few feet from my driveway with a car that's turned off all while being stared at by a dozen of the cutest shocked/confused faces I've ever seen. I have to start it up in order to drive the last 20 feet to its spot. I don't say a word as I retreat to the safety of my garage. I'm friends with a few of the witnesses and the next day they told me how half the cheer team got a pretty good laugh at the kid who drove his old sports car into their trashcan and made the engine die. I wasn't checking them out I swear! They'll never believe me.

[Flieger]

I will have to remember that one when Spring Quarter starts. Although, I will have to add a flourish with a handbrake turn in my best TopGear tribute.