how hot is too hot?

[Jetronic]

On another forum, someone was measuring the temp of the turbo oil feed line after a few minutes of WOT, and it was 240°C (464°F). Obviously this is the outside of the line, and it gets heated by the radiance from the turbine, but it can't be good for the oil or the turbo bearings.

Same engine as in the Dart 1.4 MA btw...

Quote:

Long story short: normal driving 15 minutes, expressway full pelt for a couple of miles, another mile or so of slow driving, 30 seconds idle, engine off.

Turbine side of the turbo oil line: 240 degrees celsius.

A bit much to leave it at that, so I started the engine again, and after two minutes of idling, temp was down to 170. Still high, so I think I'll be constructing some kind of a heat barrier between the pipe and the turbine housing.

 

[Cujet]

Lord knows if this is a accurate measurement. However, as a very experienced turbocharged engine builder and user, the choice of oil remains very important. Coking has been, and continues to be an issue with turbochargers and the drain lines.

 

[Jetronic]

in this case the feed lines coke up...

http://www.alfaowner.com/Forum/alfa-mito/835833-qv-dead-turbo-3.html

post 62 has a picture of the feed line from a failed turbo.

 

[Olas]

All manner of heat management products are available which claim to insulate the hot side of the turbo, plus the engineers who designed and built the car should have taken it into consideration..

However, as with all forced induction machines, the mantra
"spool then cool" still applies

 

[DeepFriar]

What would now be considered an acceptable temp for the line at that point? This issue drove the use of ester oils back in the 90's along with wraps, various Swain coatings and ceramic ball bearings.

 

[lubricatosaurus]

At least Ford's Ecoboost doesn't even require synthetic oil:

“During normal turbo operation, the turbo receives most of its bearing cooling through oil,” said Keith Plagens, turbo system engineer. “After shut down, the problems with turbos in the past were you would get coking in the center bearing. Oil would collect in the bearings, the heat soaks in and the oil would start to coke on the side and foul the bearing. Water cooling – used in the EcoBoost engine – eliminates that worry.”

The new EcoBoost V-6 uses two Honeywell GT15 water-cooled turbos.

“The EcoBoost engine uses passive thermal siphoning for water cooling,” Plagens explains. “During normal engine operation, the engine’s water pump cycles coolant through the center bearing. After engine shutdown renders the water pump inactive, the coolant flow reverses. Coolant heats up and flows away from the turbocharger water jacket, pulling fresh, cool coolant in behind. This highly effective coolant process is completely silent to the driver, continuing to protect the turbocharger.”

More torture details: http://www.at.ford.com/news/cn/ArticleArchives/Red-HotTortureNewEcoBoostEngine%E2%80%99sTurbochargersGlowinDurabilityTesting.aspx

 

[DeepFriar]

I had an '86 Audi Turbo back then and it used an after-running water pump that ran water over the center bearing. The cooling line was T'd into the regular upper hose. It was quite vocal and you could always tell if it was working. I had the car for five years and never had a problem with the turbo. Unlike the rest of the car!

 

[philipp10]

well my take is, I would assume the engineers that designed and tested it felt it was ok as it.....maybe I am niave but do you really want to redesign your car?

 

[Jetronic]

I don't have a 1.4 so don't know for sure but it seems the turbos are water cooled aswell. but the oil feed line isn't...

My diesel doesn't have water cooling

 

[Jetronic]

I don't have a 1.4 so don't know for sure but it seems the turbos are water cooled aswell. but the oil feed line isn't and there's no electric pump for cooling after shutdown.

My diesel doesn't have water cooling for the turbo

 

[DeepFriar]

Good data on GT15 here, maybe a bit dated. VERY widely used, Honeywell must make a ton on these. Siphon cooling, as you mention, is a very elegant engineering solution:

http://turbochargerspecs.blogspot.com/2011/02/garrett-gt15-gt1544-both-150-hp-turbos.html

 

[SteveSRT8]

Sounds like it's time to wrap that rascal. Seriously, a piece of foil backed insulation could be applied to good use here.

There will always be special cases of unique operation and insufficient R&D forever...

 

[lubricatosaurus]

Originally Posted By: philipp10
well my take is, I would assume the engineers that designed and tested it felt it was ok as it.....maybe I am niave but do you really want to redesign your car?

Anything Garrett (now Honeywell) I'd trust. I knew a few of those engineers in Phoenix in the 1980's and they were THE authority on the subject.
Originally Posted By: DeepFriar
Good data on GT15 here, maybe a bit dated. VERY widely used, Honeywell must make a ton on these. Siphon cooling, as you mention, is a very elegant engineering solution

 

[DeepFriar]

I spent 14 years with Honeywell on the military side. Wish I could have spent some of that time with the commercial guys in Phoenix. Garrett was always top notch. Our best acquisition after Sperry really. My favorite Garrett product is the TPE331, specifically the dash 10 because of what it is attached to. If the lottery, even a small one, ever comes in I'll be out buying a Grand Rennaissance 690B.

 

[DeepFriar]

When I was involved in the Nissan community it was the GT28 series that was most often being used by the road racing guys. That may have been first use of the ceramic ball bearing center section but I couldn't swear to it.

 

[ecotourist]

Originally Posted By: DeepFriar
I had an '86 Audi Turbo back then and it used an after-running water pump that ran water over the center bearing. The cooling line was T'd into the regular upper hose. It was quite vocal and you could always tell if it was working. I had the car for five years and never had a problem with the turbo. Unlike the rest of the car!

I had an '86 Volvo 740 Turbo with an oil cooled turbo. Their water cooled turbos came out in '87.

I worried a lot about that turbo packing it in on me. So I changed the (dino) oil every 3 months, let the turbo cool off as I drove into the neighbourhood, and especially let the turbo cool off after a hot run at highway speed. That turbo did fine for my 18 1/2 years of use, and another 5 years with a friend.

 

[ecotourist]

Originally Posted By: ecotourist
... and especially let the turbo cool off after a hot run at highway speed...

I should clarify that I let the turbo cool off by idling for a couple of minutes before shutting the engine off to fuel up for example.

 

[AlienBug]

Originally Posted By: philipp10
well my take is, I would assume the engineers that designed and tested it felt it was ok as it.....maybe I am niave but do you really want to redesign your car?


The dogma of some on this site is that the engineers who design cars are unaware of things like "summer" and "highways" and that operation in warm weather or 70 mph speeds require modifications.

 

[DeepFriar]

I tend to agree with you AlienBug, Heaven knows they spend a bunch of dough on development. But if there were no engineering slip-ups there would never be any tech service bulletins or recalls. Shaft coking was a real problem for production turbos in the 80's and can still be if what we hear from others here is any indication.

 

[DeepFriar]

Summit racing has a ton of products that might be useful for protecting the oil line either via shielding the line itself, the exhaust headers or both.


http://www.summitracing.com/search/department/exhaust/section/heat-protection?N=4294948820%2B4294948817&SortBy=Default&SortOrder=Ascending