jags911tt

Do our cars have turbo timers? If not should I let the car idle for a while after driving it? If so, for how long?

TIA
Jags

Kevin

No turbo timers, 2 minutes..

Joe Weinstein

What Kevin said. And to repeat the experts, driving slowly and gently is *NOT* a
substitute for a cooldown idle for a couple minutes. The exhaust temperatures
are still significantly higher for the slowest driving than they are at idle. You want
the turbos to cool as well as they can while oil is still flowing through, so we don't
fry up whatever oil ends up staying in/near the turbos when the motor is turned off.
Joe

wross996tt

Agreed on both counts!

Craig.

Turbo timers interfere with the operation of the factory alarm.

Craig

PorschePhD

Yes, plus you need to have the key present for the transponder chip to the module. Everyone has two minutes to sit. If not, think of it as therapy

joolsbourne

I don't see how coasting the last 2mins towards home at near engine idle speeds will elevate the turbo temps and oil? If anything the airflow over the exhaust components should bring the temp down.
I always coast the last few miles through the built up area where I live. Park in the garage, sit for 5 secs, probably do an oil level cheack and shut down. No problem!

Woodster

I, like many drive mellow the last mile or so (3-5) minutes then pull into garage,
leave it idle and wipe off my wheels (takes about 2-3 minutes). Then shut down!
works like a charm!
MK

jags911tt

I have had my car for 3000 miles now and never done this. Could I have damaged something? Also is this required after short drives?

Jags

BigCarrot

That's what I do also. I figured it would be fine!

wross996tt

Once you stop the engine, the oil flow stops and therefore there is no flow through the turbos they're still spinning (and no cooling). This will bake your turbos.

joolsbourne

Who mentioned water? I understand that it's all about the oil system and the latent heat in the engine components.
My point is that cooling down with the car in motion will radiate some of the heat into the passing air. Sitting in a garage with the engine idling will soak more heat into the components.

ar38070

There is also an oil cooler and I believe that it is air cooled. While I certainly subscribe to cooling the turbos (and everything else) if you have been running hard i.e. at the track before shutting down I am less convinced of the need if you are idling along the road for a few minutes prior to shutdown.

If the car is idling with no air flow I believe that the engine temperature increases as does oil and water temps. Does anyone disagree with this?

Also, for example, what do you do when you stop for gas? Do the idler proponents sit at the pumps for 2 minutes with the car idling to cool down the turbos before shutting down?

I think the only way to really answer this question is for someone to put temperature probes on the turbos and see what is really going on.

Kevin

ar- I am a supporter for letting the car idle down at the fuel pumps.. 2 minutes would be nice, but give it at least 30 seconds.

It's not the latent heat in the engine compartment but the heat soak from the turbine housing cooking the turbine seals. Once the engine is shut off, oil cannot cool the turbine wheel. The shaft blues at over 700 degrees. I see it everyday. Turbo after Porsche turbo, coming in for repair from smoking/leaking issues.

ar38070

Kevin,

I am not doubting what you see and I know that you have seen a lot of engines, however some questions come to mind:
The turbos that you see, exactly how were they treated ? Your customers may say "I always cool down my turbos for 2 minutes" but did they really? Or do they say "I never cool off my turbos"?

You only see "broken" turbos I would think. What percentage of the turbo population in your area is that?

How many "bad" heat cycles does it take to cause a problem? Is the effect cumulative? Does correct cooling down reverse the effects of a "bad" heat cycle? Or if you screw up a couple of times are you hosed forever?

Latent heat in the engine compartment effects the cooling of engine components. The turbine housings are hot. They will cool faster with external air flow than without. Therefore cooler housings will not cook the turbine seals as much as hotter housings. If the car is sitting still, everything in the engine compartment is getting hotter. True or not?
Rhetorically speaking, how many turbos do you not see that are not cooled down but do not have problems?

Now I can agree that if you always cool down your turbos then you probably wont have any problems. However I do not think that anyone can say if you only run "easy" for five minutes before you shut down that you will have problems.

Again I think the only definitive answer will be if someone takes appropriate temperature readings under the different scenarios to see that the relative cooling rates are.