Cooling the Boxster's Engine After a Drive....
08-03-2012 | 11:34 AM
#16
Nordschleife Master
Joined: Nov 2010
Posts: 7,804
Likes: 191
From: Bay Area
Vet you are correct. People used to use turbo timers on turbo charged cars. A whole industry of turbo timers have been sold based on paranoia/bling. I was suckered into one a long time ago. The older turbos that used to be oil cooled only could have used one if you didn't want to idle the car after a hard run. Nowadays turbos are both oil and water cooled so turbo timers are not needed and are generally considered 'ricer' mods.
I suppose a turbo timer would be useful for those of you that want to idle your cars everytime after driving them. You can set how long to run the engine after pulling the key out.
I suppose a turbo timer would be useful for those of you that want to idle your cars everytime after driving them. You can set how long to run the engine after pulling the key out.
08-03-2012 | 03:56 PM
#17
Race Director
Joined: Sep 2006
Posts: 19,032
Likes: 256
From: Centerton, AR
I concur. The right "intake" is for the fan to suck air in and blow into the engine bay. The air escapes from the bottom of the car. Alan, the hot air you felt may have been hot air coming all the way around - engine bay -> ground -> sideways -> up at you.
At the Tech Tactics, a guy from Porsche was even joking how it's not a good idea to park a Boxster on a dusty road with the top down. The fan will blow air out the bottom of the car and create a dust cloud... you get the picture.
I don't worry about cooling the engine much, but this is an interesting thread because I thought that the fan will come on even if the car is turned off. Usually doesn't do it immediately but will do so after a few minutes. I thought I read that somewhere and thought I've seen it in my Boxster... now I'm not so sure...
Don't know why but I've been thinking about this recently. The fan definitely goes off when you turn the car off. However, IIRC it is supposed to come back on in a few minutes *if* the engine bay gets too hot. I was told that the older, oil-cooled turbos should be idled after hard driving (e.g. track) because the turbo turns cherry red hot. The same person then said that it's not a concern on modern turbos because it's built to deal with it - don't know how... maybe the fan coming on?
At the Tech Tactics, a guy from Porsche was even joking how it's not a good idea to park a Boxster on a dusty road with the top down. The fan will blow air out the bottom of the car and create a dust cloud... you get the picture.
I don't worry about cooling the engine much, but this is an interesting thread because I thought that the fan will come on even if the car is turned off. Usually doesn't do it immediately but will do so after a few minutes. I thought I read that somewhere and thought I've seen it in my Boxster... now I'm not so sure...
Don't know why but I've been thinking about this recently. The fan definitely goes off when you turn the car off. However, IIRC it is supposed to come back on in a few minutes *if* the engine bay gets too hot. I was told that the older, oil-cooled turbos should be idled after hard driving (e.g. track) because the turbo turns cherry red hot. The same person then said that it's not a concern on modern turbos because it's built to deal with it - don't know how... maybe the fan coming on?
As I touched upon above, in an earlier post, older Boxster engine compartment fans do not come on after the engine has been shut off. Newer MYs might have changed in this regards.
The turbos can run pretty hot. A portion of the hottest area might get hot enough to climb to a dull red color from heat provided it wasn't too bright at the time.
If someone is tracking a turbo charged car and comes in off the track from a hot lap with no cool down lap and then doesn't at least allow the engine to idle he doesn't really deserve a turbo charged car.
While modern turbo charged cars that have water cooled turbos are a bit better in this regard they still need some idle time to allow the considerable heat load to make its was into to the coolant.
While the outside of the turbo is hot enough after hard running the exhaust turbine is even hotter.
If the engine is shut off with the turbine hot that heat of course heats up the shaft which in turn heats up the oil around the shaft -- the shaft probably runs in a plain/hydrodynamic bearing -- which can bake the oil and this form abrasive compounds that do some damage to the bearings but more likely the more sensitive seals the next engine start. Over time...
So, even with a water cooled turbo the engine should be idled some to give the heat time to move from the very hottest parts of the turbo (and from other parts of the engine... if the turbo is too hot what about those exhaust valves?) into the coolant and then from the coolant into the ambient air.
Sincerely,
Macster.
08-03-2012 | 04:09 PM
#18
Nordschleife Master
Joined: Nov 2010
Posts: 7,804
Likes: 191
From: Bay Area
The turbos can run pretty hot. A portion of the hottest area might get hot enough to climb to a dull red color from heat provided it wasn't too bright at the time.
If someone is tracking a turbo charged car and comes in off the track from a hot lap with no cool down lap and then doesn't at least allow the engine to idle he doesn't really deserve a turbo charged car.
While modern turbo charged cars that have water cooled turbos are a bit better in this regard they still need some idle time to allow the considerable heat load to make its was into to the coolant.
While the outside of the turbo is hot enough after hard running the exhaust turbine is even hotter.
If the engine is shut off with the turbine hot that heat of course heats up the shaft which in turn heats up the oil around the shaft -- the shaft probably runs in a plain/hydrodynamic bearing -- which can bake the oil and this form abrasive compounds that do some damage to the bearings but more likely the more sensitive seals the next engine start. Over time...
So, even with a water cooled turbo the engine should be idled some to give the heat time to move from the very hottest parts of the turbo (and from other parts of the engine... if the turbo is too hot what about those exhaust valves?) into the coolant and then from the coolant into the ambient air.
Sincerely,
Macster.
If someone is tracking a turbo charged car and comes in off the track from a hot lap with no cool down lap and then doesn't at least allow the engine to idle he doesn't really deserve a turbo charged car.
While modern turbo charged cars that have water cooled turbos are a bit better in this regard they still need some idle time to allow the considerable heat load to make its was into to the coolant.
While the outside of the turbo is hot enough after hard running the exhaust turbine is even hotter.
If the engine is shut off with the turbine hot that heat of course heats up the shaft which in turn heats up the oil around the shaft -- the shaft probably runs in a plain/hydrodynamic bearing -- which can bake the oil and this form abrasive compounds that do some damage to the bearings but more likely the more sensitive seals the next engine start. Over time...
So, even with a water cooled turbo the engine should be idled some to give the heat time to move from the very hottest parts of the turbo (and from other parts of the engine... if the turbo is too hot what about those exhaust valves?) into the coolant and then from the coolant into the ambient air.
Sincerely,
Macster.
08-03-2012 | 04:16 PM
#19
Race Car
Joined: Jan 2008
Posts: 4,690
Likes: 726
From: Scottsdale, AZ
After I come off the track, I let the engine idle until I can read the oil level. Typically, this takes 40 - 50 seconds. That lets me check the oil, lets the engine cool a bit, and lets the oil drain to where it belongs. After that, the engine fans do their thing.
The only 'cool down' I do when driving on the street is the 1/2 mile drive through our subdivision with 25mph speed limit. Lets things cool a bit and keeps the neighbors happy. The latter is probably more important.
The only 'cool down' I do when driving on the street is the 1/2 mile drive through our subdivision with 25mph speed limit. Lets things cool a bit and keeps the neighbors happy. The latter is probably more important.
08-03-2012 | 06:00 PM
#20
Instructor
Joined: May 2011
Posts: 141
Likes: 0
From: Houston, TX
About the only thing I do is leave the garage door open when the fan kicks on after a drive on a hot day. LMAO at the people buying external fans for the boxster. I wonder if there are any negative externalities for cooling your engine too fast.
The only OCD thing I do is shut the AC compressor off early to prevent the moldy smell down the road.
The only OCD thing I do is shut the AC compressor off early to prevent the moldy smell down the road.
08-03-2012 | 06:40 PM
#22
Three Wheelin'
Joined: Sep 2011
Posts: 1,795
Likes: 19
From: PA
Thank you for various info and the thread, gentlemen.
08-04-2012 | 12:00 AM
#23
Rennlist Member
Joined: Oct 2002
Posts: 1,206
Likes: 0
From: Santa Clara, Ca
Few years ago we bought a 2002 S for her. Now she does the same thing.
This is what I posted in another forum.
http://www.babblers.org/forums/showt...6292#post56292
