Cooling turbos down ?
Discussion
I know conceived wisdom with turbos is to let them cool down before switching off, I remember reading that this was to allow the oil to circulate whilst the turbo, sometimes glowing red can cool down a bit so when the oil stops being pumped around it doesnt carbonise in the bearings.
Is this still as critical ? given that a lot of turbos are now water cooled and most use synthetic oil, does this still carbonise ? do diesel turbos get as hot as petrol ones, my thinking is that you wouldnt want to stick your tongue on it but they dont get quite as hot as diesels tend to run a bit cooler (or do they ?) , but the heat may be more a function of masses of compressed air and than combustion.
I suppose it is good practice to err on the side of caution, but is this advice still valid ? does anyone still use a Turbo Timer outisde of massively boosted jap imports ?
Is this still as critical ? given that a lot of turbos are now water cooled and most use synthetic oil, does this still carbonise ? do diesel turbos get as hot as petrol ones, my thinking is that you wouldnt want to stick your tongue on it but they dont get quite as hot as diesels tend to run a bit cooler (or do they ?) , but the heat may be more a function of masses of compressed air and than combustion.
I suppose it is good practice to err on the side of caution, but is this advice still valid ? does anyone still use a Turbo Timer outisde of massively boosted jap imports ?
Car engines don't have to work hat hard normally and they are designed to be driven my people that don't know how they work. Normally if you just slow the last mile of you journey down to a gentle canter that should be enough. It is not as though cars are run under full load of hours at a time.
The situation will be improved with water-cooled turbos and advanced oils, but you still wouldn't want to get the turbo nice and toasty then switch off imo. Keep it off boost for the last bit of your journey (not hard really) and it'll cool enough.
I imagine the newer cars with electric water pumps will keep circulating after the engine is off if the turbo is too hot anyway.
I imagine the newer cars with electric water pumps will keep circulating after the engine is off if the turbo is too hot anyway.
Willy Nilly said:
Car engines don't have to work hat hard normally and they are designed to be driven my people that don't know how they work. Normally if you just slow the last mile of you journey down to a gentle canter that should be enough. It is not as though cars are run under full load of hours at a time.
Yeah was thinking your acerage Renault Scenic diesel driver isnt getting the turbo glowing like the one on a 1980's F1 car, thinking more enthusiastically driver modern stuff.
You can buy turbo timers which keep the engine running for a predetermined time after you remove the keys from the ignition.
http://en.wikipedia.org/wiki/Turbo_timer
http://en.wikipedia.org/wiki/Turbo_timer
TheHeretic said:
You can buy turbo timers which keep the engine running for a predetermined time after you remove the keys from the ignition.
http://en.wikipedia.org/wiki/Turbo_timer
I have one on the Skyline; but can't bring myself to walk away from a locked, running car so don't use it.http://en.wikipedia.org/wiki/Turbo_timer
I just cruise gently for the last few mins to let the turbo cool a bit.
V8 Disco said:
I have one on the Skyline; but can't bring myself to walk away from a locked, running car so don't use it.
I just cruise gently for the last few mins to let the turbo cool a bit.
That's what I used to do on the Mr2. Seldom see the point in driving in 'loon mode' right up to your destination. I just cruise gently for the last few mins to let the turbo cool a bit.
TheHeretic said:
V8 Disco said:
I have one on the Skyline; but can't bring myself to walk away from a locked, running car so don't use it.
I just cruise gently for the last few mins to let the turbo cool a bit.
That's what I used to do on the Mr2. Seldom see the point in driving in 'loon mode' right up to your destination. I just cruise gently for the last few mins to let the turbo cool a bit.
Hi,
On my Lancer Turbo the handbook actually states a cooldown time of 5 or more minutes. This is because the original IHI Turbo unit needed to cool down sufficiently in order to stop the (not fantastic quality) oils of the day carbonising within the feed galleries (as previously mentioned) and w
king the unit. Having had a few units apart, the effect of a poor quality oil on a naff (which they are) Turbo is terminal. I've seen it baked onto the thrust bearing.
I've since fitted a water cooled Garrett T04 via an adaptor plate, however, I was informed by one of the Graham Goode mechanics that when a turbo is glowing red and under severe load, the water being passed through essentially turns to steam and does no cooling whatsoever, it only serves to push the coolant temperature up. I admit, on the few times I give my Lancer serious beans, the coolant temp does noticably increase in conjunction with the boost. Not sure if this has any detrimental effect or is just one of those things that 30 year old turbocharged engines have a habit of doing.
Back to the OP, I always out of habit leave my turbo to cool down, either by gentle off boost driving or sitting at idle for a minute or so. Same goes for the warm up.
Edit - if running silly amounts of boost then I'd say despite stuff like Mobil 1 kicking about, and advances in Turbo technology, it won't do any harm in allowing a period of time for cooldown. When mobil 1 first came out and we started running it in our Lancers, the carbonising problems did actually stop.
On my Lancer Turbo the handbook actually states a cooldown time of 5 or more minutes. This is because the original IHI Turbo unit needed to cool down sufficiently in order to stop the (not fantastic quality) oils of the day carbonising within the feed galleries (as previously mentioned) and w
king the unit. Having had a few units apart, the effect of a poor quality oil on a naff (which they are) Turbo is terminal. I've seen it baked onto the thrust bearing.I've since fitted a water cooled Garrett T04 via an adaptor plate, however, I was informed by one of the Graham Goode mechanics that when a turbo is glowing red and under severe load, the water being passed through essentially turns to steam and does no cooling whatsoever, it only serves to push the coolant temperature up. I admit, on the few times I give my Lancer serious beans, the coolant temp does noticably increase in conjunction with the boost. Not sure if this has any detrimental effect or is just one of those things that 30 year old turbocharged engines have a habit of doing.
Back to the OP, I always out of habit leave my turbo to cool down, either by gentle off boost driving or sitting at idle for a minute or so. Same goes for the warm up.
Edit - if running silly amounts of boost then I'd say despite stuff like Mobil 1 kicking about, and advances in Turbo technology, it won't do any harm in allowing a period of time for cooldown. When mobil 1 first came out and we started running it in our Lancers, the carbonising problems did actually stop.
Edited by texaxile on Sunday 5th May 22:57
I don't see the sense in the argument that turning the cooling water to steam doesn't cool the turbo.
It takes thermal energy to change water from liquid to gaseous state, ergo in turning it to steam the turbocharger has given up some thermal energy (I.e. heat) to the coolant. The rise in water would partially result from the extra heat from the turbo as well as from the engine itself.
Although the turbine side will glow at high load, the core (where the bearings and any cooling gubbins live) will be nowhere near as hot - unless cooling/lubrication fails in which case things melt, sieze and die a horrible mechanical death.
The logic behind extended idling following a fast run is that the heat conducted from the potentially red hot turbine side into the core can "cook" the oil, oil seals etc and knacker the bearings through oil starvation when next run. Also in extreme cases the heat soak can result in the shaft becoming soft enough to droop (although if it's hot enough for this the turbine wheel has probably partially melted and the bearings and seals are already wrecked!).
It takes thermal energy to change water from liquid to gaseous state, ergo in turning it to steam the turbocharger has given up some thermal energy (I.e. heat) to the coolant. The rise in water would partially result from the extra heat from the turbo as well as from the engine itself.
Although the turbine side will glow at high load, the core (where the bearings and any cooling gubbins live) will be nowhere near as hot - unless cooling/lubrication fails in which case things melt, sieze and die a horrible mechanical death.
The logic behind extended idling following a fast run is that the heat conducted from the potentially red hot turbine side into the core can "cook" the oil, oil seals etc and knacker the bearings through oil starvation when next run. Also in extreme cases the heat soak can result in the shaft becoming soft enough to droop (although if it's hot enough for this the turbine wheel has probably partially melted and the bearings and seals are already wrecked!).
Gassing Station | General Gassing | Top of Page | What's New | My Stuff