So, a thought that's occurred to me more than once.

1) How come I don't see anyone running a dedicated oiling system for their turbo?

2) Is it simply a matter of the current system being adequate?

3) What makes the bearings go south on these things?

4) Would the ability to run a thinner, higher quality oil help with the longevity?

A tank, pump and oil cooler would be a piece of cake. I'm guessing on the racers it's also a matter of weight savings being a possible hindrance.

---Cobra

 

You hit the nail on the head with #2 there. There's nothing wrong with the standard way of doing it, and it works just fine.

 

You wouldn't set up a separate oiling system for a turbocharger for the same reasons you wouldn't install a septic system for the upstairs toilet in a house that's already connected to a fully functioning sewer system.

 

I was under the impression that the turbos run tighter tolerances, than say, a main bearing. Spinning considerably higher rpm, I would think a higher quality oil (septic system) would benefit that individual system.

I take it the previous answer is the long way of saying, "...the current system has proven adequate in a number of different applications."

I suppose if it were enough of a benefit you'd see it in 24hr endurance racing events.

---Cobra

 

The loads on a turbo bearing are totally different than what a main or rod bearing sees. At the end of the day, there just needs to be oil in there and it will work fine.

 

Duly noted. Thank you.

 

I suppose one could make the argument that there might be some theoretical benefit to providing the turbo with its own oiling system separate from the engine. Apart from being able to run separate grades of oil in the two, my guess is that your principle concern here involves the cleanliness of the oil, and I'm certain you're right in that oil reserved specifically for the turbo would remain much cleaner in the absence of combustion blowby, fine metallic particles shed by the various bearing surfaces, etc. Whether this would have any practical benefit to the turbo is questionable; neither journal-bearing turbos nor ball-bearing turbos are nearly as close-tolerance devices as you might imagine.


In the end, I doubt that the added cost and complexity of such a configuration would be justified. In matters such as these, I tend to use a very simple analysis: Are those at the top echelons of motorsport doing it? Are high-end OEMs doing it?

If any given technology isn't in use by Mercedes or Porsche, nor banned in F1, then it's probably not quite as awesome as you might have thought.

 

Well, to be fair, a turbo oil system effectively *is* banned in F1, because the turbo that it would lubricate is banned, at least until 2014.

I suspect the biggest reason you wouldn't see one on an all-out race car is that it's not worth the added weight.

--Ian

 

plus it would be just one more thing that could go wrong and mess everything up

 

Ok, wise guy. You know what I mean.

In some series, perhaps. But consider endurance-style races (Le Mans, Lemons, Daytona) and particularly those which involve an off-road element (Dakar, Baja, WRC). If those guys were suffering turbo bearing failures, and an extra 15 lbs of weight would cure this, I'm pretty sure they'd all be running external lube systems.

For a street car, of course, I still hold up companies like Mercedes and Porsche as the final arbiters. These are the companies which stake their reputation on building high-HP, high-reliability powertrains for everyday use.


Do we have any diesel mechanics among us? Truck owners hang all sorts of fancy oil-purification devices on their rigs in order to extend their oil-change intervals. At 12 gallons a pop and 150,000 miles or more a year, the OTR guys have good reason to run their oil as long as possible, and weight is certainly no concern there. Do any of these rigs use self-contained lubrication systems for the turbocharger, or do they consider oil that's got 20,000 miles worth of diesel blow-by in it to be perfectly adequate for a turbocharger that spend more time on boost in a week then any of our engines spend running in a month?