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Shreks Donkey Profile
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Date Registered: 02-2009
TOTAL POSTS: 63
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Re: T31 Diesel Turbo Timer


quote:

Swagman wrote:

Interesting thread guys.

quote:

Shreks Donkey wrote:
 There is no coolant or anything inside a turbo....if there is....i`d be worried.



From Renault's promo stuff about the M9R:
"The new car will be available with two types of Alliance engines. The 2.0 dCi Euro 4 diesel engine (M9R) is available in a choice of two power outputs, namely 110 kW or 127 kW. The engine, which has already been seen on upper-range Renault vehicles, Mégane, Nissan's Qashqai and New X-Trail and Renault Samsung Motors' QM5, features the very latest diesel engine technologies, including piezoelectric injectors, common-rail 1,600-bar fuel injection, a water-cooled variable-geometry turbo and a periodic regeneration particulate filter.



Once again, they`re just referring to the intercooler when they say water cooled. Perhaps it`s just the European way of saying intercooled and once again has nothing to do with post drive protection of the turbo.

17/Jul/2009, 6:30 pm Link to this post Send Email PM   Send Private Message
 
jalalski Profile
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Date Registered: 02-2004
Location: SUTHERLAND, SYDNEY
TOTAL POSTS: 29094
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Re: T31 Diesel Turbo Timer


quote:

Shreks Donkey wrote:
I believe what you`re saying here is also referred to as an intercooler.



Sort of, but the correct definition of an intercooler as follows:

Charge air cooler: A radiator placed between the turbo compressor outlet and the engine intake manifold used to cool the intake charge, which is heated by the compression of the turbo (also called an intercooler).

quote:

As you say this has nothing to do with protecting the turbo AFTER shutdown. It`s more about cooling the turbo air, which reduces the volume of air and therefore allowing cooler molecules into the cylinders to protect the engine.



Exactly.



---

17/Jul/2009, 6:39 pm Link to this post Send Private Message MSN Blog
 
dronus Profile
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Date Registered: 08-2008
Location: Adelaide
TOTAL POSTS: 541
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Re: T31 Diesel Turbo Timer


Car is booked in for wednesday. Ill have a chat with them about what they recommend, and the points brought up in this thread.

---
Current - GU Patrol
Old - '08 T31 Platinum TL Diesel Manual - Bells and whistles.
Older - '04 T30 Ti-L Auto
X-966
18/Jul/2009, 10:37 am Link to this post Send Email PM   Send Private Message MSN
 
Swagman Profile
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Date Registered: 05-2009
Location: Victoria, Australia
TOTAL POSTS: 16
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Re: T31 Diesel Turbo Timer


Thanks for the replies guys,

quote:

jalalski wrote:
In regards to the noise you're hearing, it could well be the Journal bearings which are a Hollow brass sleeves suspended in oil that allow the turbo shaft to spin freely inside the centersection.



Could be...but then I would expect that the noise would cease within a few seconds (once the rotor slowed down and stopped) after switching off. The noise I hear is a high-pitched wine (electric motor whine) that continues for about 3 to 4 minutes after switch off - longer when the engine is hotter. (Actually there is also another noise - a series of about 15 to 20 quite loud "clicks" about a second or so apart for about 15 seconds after switch off - but that's probably something unrelated).

Maybe we'll have an explanation what produces these noises after Wednesday when Dronus gets his vehicle back.

Incidentally, I've done a lot of reading about the new crop of water-cooled turbos in the last few days. The new technology is heaps different from the old. Two good explanations I found might interest M9R owners.

From Garrett:

"Following a hot shutdown of a turbocharger, heat soak begins. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo’s center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking.

To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after engine shut down. The layout of the pipes should minimize peaks and troughs with the (cool) water inlet on the low side. To help this along, it is advantageous to tilt the turbocharger about 25° about the axis of shaft rotation.

Many Garrett turbos are water-cooled for enhanced durability"

From APS:

"Whilst turbochargers began to be applied to passenger cars in the late 1970s in response to the energy crisis, the first generation passenger car turbochargers were derived directly from commercial diesel engines. Engine oil was used to provide both lubrication and cooling and whilst this was an effective compromise between cost, durability and performance, in high engine performance applications durability suffered through fouling of the turbocharger bearings through high turbine and bearing temperatures.

By encasing the turbocharger bearings in intricate water passages, engine coolant is used to significantly reduce turbocharger bearing temperatures in order to eliminate the coking and lacquering issues that fouled old fashioned turbocharger bearings. Non water cooled turbochargers have no place in a high performance gasoline engine application and should be avoided at all costs."

This (and lots of other stuff I've found on the Web) convinces me that the the reference to "...water-cooled turbo..." I quoted earlier isn't a reference instead to a "...water-cooled intercooler...." for the M9R. But this obviously needs confirming by someone who has actually pulled down the turbo on the new Exy as to whether the center housing has water cooling channels and the associated connections incorporated into it.

Cheers,

Jeff.

----------------------
2008 T31 diesel TS manual, Twilight, tow pack, roof bars, left cargo drawer, all round protection mouldings, boot mat, floor mats, luggage blind
20/Jul/2009, 1:24 pm Link to this post Send Email PM   Send Private Message
 
guvnor1966 Profile
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Date Registered: 06-2009
TOTAL POSTS: 30
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Re: T31 Diesel Turbo Timer


HI Guys, in a similar vein to engine preservation and turbo timers, for those of us new to driving turbo diesels, is there a product that prevents ignition before oil has pumped to the turbo?

Simon.

---
Simon, Benalla, VIC., X-1311.
Ex 2007 ST-S Extreme, Manual, Twilight.
New Ride 2008, TS dCi, Auto, Black - Smoked bonnet protector, h/lamp protectors, cargo mat, mats, t/bar.
21/Jul/2009, 5:52 pm Link to this post Send Email PM   Send Private Message
 
Shreks Donkey Profile
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Date Registered: 02-2009
TOTAL POSTS: 63
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Re: T31 Diesel Turbo Timer


quote:

guvnor1966 wrote:

HI Guys, in a similar vein to engine preservation and turbo timers, for those of us new to driving turbo diesels, is there a product that prevents ignition before oil has pumped to the turbo?

Simon.



 Gee what are you talking about? There is no oil that gets pumped to the turbo. It`s exhaust gases that run the turbo.

22/Jul/2009, 12:35 pm Link to this post Send Email PM   Send Private Message
 
Swagman Profile
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Date Registered: 05-2009
Location: Victoria, Australia
TOTAL POSTS: 16
Reply | QUOTE
Re: T31 Diesel Turbo Timer


quote:

guvnor1966 wrote:
For those of us new to driving turbo diesels, is there a product that prevents ignition before oil has pumped to the turbo?



That's an interesting question Simon. I recall from my Mech Eng studies at Uni in the 70s reading something that showed that the vast majority (can't recall the actual figure - maybe 80%?? - might have been even more) of ALL engine wear actually occurs within the first three revolutions of a cold engine during cranking - that brief period before the oil pump has reached delivery pressure.

Yet I've never seen any systems built into engines to start lubrication early.

I can only assume that the added complexity that would involve (timers, separate wiring, controllers, an additional electrically driven oil pump etc) is just too much of a pain. The same situation probably applies to pre-lubrication of the turbo too.

AND it's in the interest of motor manufacturers not to prolong the life of their engines TOO much!! emoticon


quote:

Shreks Donkey wrote:
Gee what are you talking about? There is no oil that gets pumped to the turbo.



I would hope that there is oil being pumped to the bearings of my Exy's turbo!!

It runs a bit bloody fast for it to run without any lube!

 emoticon

Jeff.

----------------------
2008 T31 diesel TS manual, Twilight, tow pack, roof bars, left cargo drawer, all round protection mouldings, boot mat, floor mats, luggage blind

Last edited by Swagman, 22/Jul/2009, 4:19 pm
22/Jul/2009, 3:45 pm Link to this post Send Email PM   Send Private Message
 
dronus Profile
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Date Registered: 08-2008
Location: Adelaide
TOTAL POSTS: 541
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Re: T31 Diesel Turbo Timer


Well i asked the question today when i picked up my T31 from getting serviced.

Had the answer confirmed by the Lead Mechanic aswell.

Ready for it??

The diesel engine fitted to our T31's has a pump which pumps coolant (not oil) around the turbo when you shut down the engine. This is the pump noise that you hear when you shut off your engine. It is controlled by a thermostat which will shut off the pump once the turbo reaches a safe temperature. There is also another humming noise, this is the manifold resetting, or something...

It is also fitted to the Renault cousins.

The recommendation is that if you have been driving for a while (few hours) to idle your engine for a minuite or so before shutting it down to allow the turbo to spin down etc but any longer than that isnt required. If you have only been driving for a few minuites there is no need (unless you have just got out of a bog, or something).

They seemed suprised that someone had gone to the effort to build a specific model for the x-trail!

It wont hurt your engine (i hope) but its not really required unless you cant spend the minuite idling if you cant slow down before stopping.



---
Current - GU Patrol
Old - '08 T31 Platinum TL Diesel Manual - Bells and whistles.
Older - '04 T30 Ti-L Auto
X-966
22/Jul/2009, 5:19 pm Link to this post Send Email PM   Send Private Message MSN
 
guvnor1966 Profile
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Date Registered: 06-2009
TOTAL POSTS: 30
Reply | QUOTE
Re: T31 Diesel Turbo Timer


quote:

Shreks Donkey wrote:

 Gee what are you talking about? There is no oil that gets pumped to the turbo. It`s exhaust gases that run the turbo.




Thats a sharp reply Shreks Donkey. Please read on.

"Traditional turbocharger design employs a conventional plain bearing that runs on a film of oil. This is known as a floating metal bush."

"Wear of plain bearings is influenced by the state of lubrication and, conversely, wear characteristics influence the various lubrication states."

"Wear occurs during start-up and slowdown when speed is too low to produce sufficient fluid pressure to support the bearing surfaces on a lubricant film."

And finally....

"The diagram above shows the turbocharger main shaft supported by floating metal bushes. Oil is fed through the bushes and forms a cushioning layer between the turbocharger shaft and the supporting bush. The shaft relies on a constant supply of fresh, clean oil over a very wide contact area in order to maintain sufficient clearance from the bush itself. A similar approach is used to support the turbocharger main shaft from thrust loads as well.

Whilst floating metal designs have served us well in the past, the frictional forces are relatively high. This results in sluggish turbocharger response and can be somewhat fragile in nature under extreme operating conditions.

Nissan attacked this very issue some 15 years ago on the GTR Skyline by developing a turbocharger bearing system that forms the basis of the true high performance modern turbocharger.

By utilizing robust ball bearings at either side of the turbocharger main shaft, this did away with the floating metal and thrust bushes.
"As seen in the diagram above, the turbocharger shaft is supported by two ball bearing assemblies. These again are fed with engine oil, but no longer rely on a thin film of oil over a wide area to support the turbocharger shaft.

The result is an outstanding reduction of frictional torque on the rotating turbocharger assembly in contrast to the old fashioned floating metal bushes. The improvement in turbocharger response, particularly in the lower to mid turbocharger speed range is phenomenal."

I will leave it there but if you would like to learn a little about bearing design & lubrication
then refer www.bearings.machinedesign.com & www.airpowersystems.com.

Thanks for the support Swagman.


No hard feelings but engage thinking matter before speaking.

Simon. emoticon

---
Simon, Benalla, VIC., X-1311.
Ex 2007 ST-S Extreme, Manual, Twilight.
New Ride 2008, TS dCi, Auto, Black - Smoked bonnet protector, h/lamp protectors, cargo mat, mats, t/bar.
22/Jul/2009, 6:16 pm Link to this post Send Email PM   Send Private Message
 
Shreks Donkey Profile
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Date Registered: 02-2009
TOTAL POSTS: 63
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Re: T31 Diesel Turbo Timer


How on Earth do you expect the oil to be pumped through to the turbo without the engine running? When the ignition is first turned on, the glow plugs are quickly heated up and a small amount of fuel is injected, that`s it! Now you`re wanting oil pumped, next thing you want is a/c to be nice and warm/cold before the engine is running.
Basically, instead of learning about diesels and the best way to run them, you want someone else to take that responsibility from you so that you can just turn the car on and drive without thinking.
23/Jul/2009, 5:17 am Link to this post Send Email PM   Send Private Message
 


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