Ok so turbos have turbo timers to make sure the hardware doesn't seize. How about N/A cars? Any cool down period recommended where you let the car idle after long periods of use or aggressive driving?

 

If I run mine hard, I always let it idle or drive at slow spped for a few minutes or miles. I never turn off immediately after a hard run.

 

not really ness. for NA cars but I usually cruise the last 1 mile or so before I shut off

 

Worst thing that can really happen is vapor lock, car won't start if you turn it off, because engine temp is so high that fuel evaporates before ignition point.

 

i'm usually forced to run the car easy b/c im driving into residential areas before getting to my house...if i autox/drive hard for an extended period of time, when i get home, i'll pop the hood in the shade for an hour or so

 

hmmm i may just let it idel for 2 mins from now on.

 

N/A cars normally do not have any issues w/ this. No need to be propping hoods up in the shade lol.

Good practice IS TO RUN THE CAR at a normal wear and tear w/ the radio off simply to listen to hear anything funny, also watch the RPM's at idle, or at a stop. This is simply pro-active esp. after pushing the engine a lil or alot.

My old Mitsu, after I upgraded the turbo and such, I used to let it run idle for about 5 -10 minutes after a few hard runs at the track. Back in the days, the turbos used to sieze up if you just killed the ignition and let the parts roast.

 

Ditto... The worst thing for a car do is sit there and idle. I always wanted to trick my fan to stay on for about 30 seconds after I shut the car off, but never got around to it. The more air you have moving the better... I pop the hood every so often too.

Smitty

p.s. good topic Zap

 

Agreed. I'm also in this habit, primarily because I once owned a turbocharged 'lil Subaru back in the mid 1980s. Its supposedly unnecessary in a NA vehicle, but nonetheless, a good habit.

I have to slow down anyway in the residential area near home.

 

Hmmm ok. So i guess the only way to know how much and how fast the temps fall is with a scan tool. I'll order the obd-ii this week since i've been meaning to do any anyways.

 

Owners of aircooled Porsche racecars normally take a cool down lap, but I've never heard about this on waterpumper (watercooled) cars.

W/ a turbo, it makes sense tho'.

 

I used to own a 90 eagle talon turbo and got used to being paranoid about the cooldown...if you should warm her up makes sense you should cool her down some as well

 

All I can tell you is that when I was learning to fly an air cooled Piper Turbo Arrow IV, a high performance, turbocharged, retractable rear ship with a constant speed propeller is this:

From the time you entered downwind, the start of the landing pattern, only power REDUCTIONS were allowed. This was to promote the cooling process. Any increase in power, and that included taxiing to the parking spot earned you an immediate pink slip from the examiner. This required a lot of planning. After parking, a full five minutes at idle was required before shutdown. They do the same thing with heliocopter engines, but with them, the idea was to let the size of the parts equalize before shutdown.

The plain, flat and simple reason why you drive any turbo nice before shutdown can be simply explained. Because the turbocharger is driven by the exhaust gas, it easily becomes the hottest part of the engine, and if the engine is driven hard and shut down, the oil for the turbo bearings can "coke" or turn partially solid.

We are liquid cooled, so we have a built in advantage, but I hope the next paragraph will encourage you to take it easy on the turbo.

Near the end of my flying career of 25+ years, I got an opportunity to fly a Piper Navajo. This is a twin engine airplane capable of carrying 10 people. Total horsepower was 700 with both of the engines turbocharged. In a single engine ship, the engine is in front of you, so you don't see what is going on. But in this high horsepower twin, the engines are off of your right and left shoulders. My first lesson was at night, in winter (dense air), and me and the instructor were taking 8 people to Pellston, Michigan for a ski trip. After takeoff (fuel flow=50 gallons per hour per engine), we settled down into a high power climb with 42 inches of manifold pressure per engine. The cowlings were louvered for two reasons: cooling and to monitor the turbos.

Friends, at least on an air cooled engine, them turbos, and I shit you not, glowed CHERRY RED! After I noticed this, I excitedly brought this up to Gerry, the instructor. His reply: Normal.

 

dfreder370,
so a cool down on liquid cooled, n/a is unecessary or a precaution that could be taken?

 

I agree with many that ideling is not the best way to cool down an engine... Think about cool air flow. driving gently with lots of air flowing through the radiator is a much better way.

 

Yeah, i work on a campus and there is a route i can take which forces me to stay in 1 or 2nd gear at about 10mph for about 5 mins or so. I did it this morning and the engine seems to shutdown more smoothly than it usually does. I'll have to do this for a while and see if i notice the same thing.

 

haha yeah Nova roads let u go just slow enough to admire the views

 

Zapata: I would just drive the car nice for the last five minutes or so. My director at work just bought a turbo saab, and before they let him drive off, they gave him quite a spiel about not driving the car hard and doing a quick shutdown. If I were a turbo owner I would treat it with respect simply because I wouldn't want to shell out the $2,000 or so to replace the thing!

I don't know about turbo cars, but on the airplane turbos, the shaft the turbo spins on had a pre engineered "weak point". It was there because if a turbo bearing froze (one of two bearings), at least the impeller could somewhat rotate, rather then stop completely dead. This way, you lost all functionality of the turbo, but at least the engine still produced some power.

All you turbo owners better be pretty persnickity about doing proper and frequent oil changes.

 

The turbo timers are to protect the turbo itself, not the engines!:P

 

My understanding of this is that a turbocharger is reaching several hundred degrees while running hard. With the engine idling for a while the coolant and oil will cool the turbo quite a bit but the rest of the engine will actually get hotter unless the fan is running. I usually just drive gently for the last few miles to cool down an NA engine.