Turbo.. to idle or not to idle...

[Tumble]

that's a fantastic picture.. hmmm.. new desktop coming on

[[GSV]Trig]

http://freespace.virgin.net/astra.tu...ng%20Turbo.wmv

[Nox]

I just don't drive over about 3k rpm for last 5-10 mins of driving. Then you get a decent airflow over the turbo/engine without working it too hard.

Nox

[Lowe]

Definitely let them cool , to be honest whats a minute a day compared to a new £600 turbo?

I always let my scoob idle for a bit (mental note to self - buy turbo timer wiring loom).

One born every minute for the tuners

[Butuz]

Well - when i get my 200sx - i'll be giving it a minute in the morning before i pull off, and a minite before turning the engine off. Most 200sx owners seem to swear by doing this. *shrug*

Butuz

[Vimeous]

Next door neighbour discovered that his old (D-Reg) Volvo 760 Turbo needed to cool....after 4 new turbos, on average 1 every two years. That's impatience for ya.

TiG I suspect your turbo is relatively unstressed and may not heat up as much as most (despite 180bhp). However a minute or so after hard driving should still help.

[headbrace]

Hmmm, this is certainly a v. interesting thread. My dad's car's instruction manual says nothing about this, nothing one way or the other. Would be interesting to see what the manufacturers think.

[Zak33]

gotta sit up there with Jiff on this one.

Things to consider:

A: any car with a turbo has it spinning ALL the time.....if it didn't, unless you had a turbo-by-pass loop (to allow gas around it) the engine would be blocked and would stall, or choke up and nearly stall.

B: Exhaust gas is really hot at the exaust ports...it dissipates SOME heat in the manifold BUT effectively the turbo is being heated with flame heated exhaust gas EVEN AT TICK OVER!!!!

C: The oil in the turbo is half the problem. The fact that it does "fry" when the engine is cut is a worry, BUT the effect that oil has next morining on your oil in the sump is equally scary. It is literally degrading it. If left to tick over for a few minutes it HELPS. A really really good stystem uses ELECTRIC OIL PUMPING to the turbo, and it stays on too....even after the engine is off.....and while we're at it, dry sumped so it is in a seperate tank.

But for real life, the car that worries me the MOST is Trig's Calibra Turbo.

Why? Because if it is the standard stuff, the turbo is CAST INTO THE EXHAUST MANIFOLD AND SPOOLS UP AT VERY LOW REVS INDEED....hence making it a great low-lag setup....BUT its also asking for the most trouble long term . He knows to keep the oil clean, and it will be fine....but thats cos OIL IS GOOD QUALITY and can look after itself in todays engineering.

Lowes turbo is a long way from his exhaust valves. AND his turbo is literally spinning at almost nothing at low revs, SO when he drives home slowly for the last two miles, his is probably in best condition. Water cooled or not.

Lasty.....in the 80's people like Audi experimented with seperate oil reservoirs for the turbo....seperate to the engine oil. Nothing would make ME happier than a high boost turbo with its own oil sump, and a big electric pump that rant after switch off to lube the turbo WITHOUT the engine turning......specially if a water supply for the turbo was also on the system.

Dont think such a thing exists tho....make you a rich man to build one tho

[Zak33]

Well - when i get my 200sx - i'll be giving it a minute in the morning before i pull off, and a minite before turning the engine off. Most 200sx owners seem to swear by doing this. *shrug*

Butuz

Well thats cos they love their cars...AND cos lots of cars actualy restrict boost for the first mniute anyway.

(Even Zafira DTI's do....you can tell....as you pull up a hill when its stone cold, and change gear a few times, it feels really slow...then.....bosh...of ya go )

[doll]

Whilst I'm not going into huge detail here (I believe Jiff wants to kick an arguement off so lets see what he has to say ) unless you've been driving the car hard, a simple drive off boost for the last few miles of your trip with the heater on hot is sufficient to cool the turbo down to the point where you won't destroy the oil sat in the turbo at time of ignition cut. Turbos are mostly water cooled as well as oil cooled - and sitting there idling will heat up the water and oil since air isn't running over the coolers.. i.e radiator and oil cooler.

Dude, this topic does not have much to do with water temperature, the coolant helps to cool the oil flow around the turbo, but you have to consider the temperature of the oil in the system vs. the temperature of the coolant. Leaving the heater on hot in the car will not do much, other than cooling down your water temp in the system (which isn't a bad thing as this will reduce coolant pressure). Some cars have auxiliary water pumps that keep working after the engine is switched of, this helps to cool the oil for a few more minutes (the 19 had this if you remember).

The reasons for idleing your car before switching off after a thrash is to allow cooler oil to flow around the turbo, to reduce the temperature. Another is, for example, if you were to thrash your car come to a complete stop and switch off your engine the turbo would still be spinning, without the oil pump circulating oil. Switching off straight away would mean that the turbo would be spinning with no oil feed, thus reducing the life of the turbo. The other reason has already been mentioned and that is the oil burn within the turbo (creating carbon deposits in the bearing), which is one of the reasons that you are running a proper oil (*plug* Motul 300v Power *plug*)

[Zak33]

doll.....once the engine STOPS, the turbo screeches to a halt.

No air getting in......no piston movement.....no turbo spin. It doesnt have free air to turn in. Its like blocking the air inlet....cos the pistons stop. Turbo stops within....(guesses) 2 seconds....its sucking on a vacuum. Some of the vlaves are shut, some partially so, and the turbo just .....stops!

[doll]

doll.....once the engine STOPS, the turbo screeches to a halt.

No air getting in......no piston movement.....no turbo spin. It doesnt have free air to turn in. Its like blocking the air inlet....cos the pistons stop. Turbo stops within....(guesses) 2 seconds....its sucking on a vacuum. Some of the vlaves are shut, some partially so, and the turbo just .....stops!

Totally disagree chap, the spindle runs on a bearing. The turbo can be spinning anything between 40,000 and 70,000 rpm when stopping the car after a good ragging. There is no way the turbo stops spinning immediately!

Edit: And I don't mean the turbo is spinning for like half an hour, i'm talking seconds.

[[GSV]Trig]

But for real life, the car that worries me the MOST is Trig's Calibra Turbo.

Why? Because if it is the standard stuff, the turbo is CAST INTO THE EXHAUST MANIFOLD AND SPOOLS UP AT VERY LOW REVS INDEED....hence making it a great low-lag setup....BUT its also asking for the most trouble long term . He knows to keep the oil clean, and it will be fine....but thats cos OIL IS GOOD QUALITY and can look after itself in todays engineering.

The only reason my car worries you if because of the loose nut behind the steerin wheel

[Butuz]

And the loose nut in the drivers head

Butuz

[Shogun]

I actually read a short article about this the other day, I forget where though unfortunately, which basically agreed with Lowe. With a modern watercooled turbo it won't be significantly hotter at the end of the journey than the rest of the engine unless you've been really spanking it.

this OTOH I'd be inclined to let idle for a while:



Story here: http://www.autospeed.com/cms/A_2311/article.html

Rich :¬)

If that pictures colours are right then according to this chart i have here that metal should be at about 1300C.. Isnt that near melting point?

[Moby-Dick]

Its probably not far off it - Mild steel melts at around 1515C IIRc , but I think you'll find that manifolds are usually a high temperature steel.

My new turbo has a much better rollerbearing core -you can hear it spinning for suprisingly long after the engine is switched off.

EDIT: Damn I had to go back through my Degree notes for that - I've forgotten a lot since University !