My ballbearing garrett died, please help indentify problem
 

Hi, yesterday went on dyno with my new setup. Unfortunately my brand new garrett gt30 didnt make through that. It started to smoke during deceleration and then suddenly stuck. Bearing separator just melted. Seems like lack of oil. But ball bearing turbos need oil restrictor (that i used). Could someone tell me is the turbo feed oil pressure is same as rest of the engine, or decreased? What is normal turbo oil feed pressure?

Is it an oil cooled or water cooled turbo. Water cooled ball bearing turbos only need a small amount of oil for lubrication and only enough oil pressure to provide the flow- i.e., not much.

Oil cooled will need a lot of oil flow but I'm not familiar with the pressure requirements.

All but underhung turbos need a lot of coolant flow, whether oil or water, to keep from failing.

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Maybe it was lack of oil, maybe not.

Too much or too little oil will kill one of these turbos.
If your oil system is configured like a 930s (recommended), then yes, you need a restrictor at the turbocharger.
If you are using an inline oil pressure regulator (Turbosmart) then you do not need a restrictor.

The other failure we have seen is incorrect ignition timing resulting in extreme EGTs, hot enough to blue the bearing and turbine housings. If your GT30R was of the generation that had phenolic bearing separators, and they failed, then the internal temps were >550F. That's a death sentence for any turbo, ball- or journal-bearing.

What the difference between 930s and regular 930? I was using standart turbo oil feed port (on top at the back of the engine)

That was a typo.
Standard 930 setup: adapter fitting on case next to thermostat, hollow bolt and banjo fitting sending oil to turbocharger, etc.

Thats what I’m using. And what about 930s? What is different?

Chris left out the apostrophe in, "930s" - with an apostrophe indicating possession, the sentence makes sense (oiling system like a 930's = oiling system like a 930 has).

Chris, would you be so kind as to explain what kills the turbo if there's too much oil?

I presume it's oil flow overwhelming the stock pump, causing it to back up and blow the seals?

Asking because I noticed this in Clewett's description of his scavenge pump (emphasis mine):

Seems like the more oil flow through the turbo bearing cartridge the better - so long as you can get rid of it?

Correct, thanks


Too much oil and the ball bearings no longer roll, but drag -- and that will wipe them out quickly.

The stock 930 scavenge pump is more than enough flow for 2x ball bearing turbochargers.
A larger VW-based (iow uses big VW gears) scavenge pump is needed if:
(a) you have a full-flow type bearing journal bearing turbocharger (ex: T3, T04) and do not wish to run an oil restrictor into it
(b) you have twin journal-bearing turbochargers
The statement about scavenging capacity for "cooling oil for ball bearing turbos" -- can't speak to that, as we don't split the turbocharger oil feed line and send some/most of it through the coolant passage, because it isn't necessary. If you're doing that, you don't understand cooling of these turbochargers, or appreciate how bad oil is as a cooling medium. Re-read Garrett's white paper on turbo cooling: the problem is *after* engine shut-off, i.e. heat soak, and there's no more oil flowing at that point, so no more "coolant" flow... no point.

https://www.garrettmotion.com/racing-and-performance/choosing-a-turbocharger/water-cooling-for-your-turbo/

Presumably above is the white paper.

Chris has installed a lot more of these than I ever will. That said, I wouldn't install a turbo without water or oil, and plenty of it, for cooling.

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"*Air-cooled engines exist in performance vehicles though and can cause some extra work for those who run them in conjunction with a watercooled turbocharger. Ideally a separate water-cooling system should be constructed, with a reservoir tank, small radiator, and possibly an electric water pump. If the thermal siphoning effect is given priority when laying out the lines and reservoir placement, a water pump may not be necessary since the heat inside the turbocharger will naturally work to circulate the cooling water through the system. If in doubt, closely monitoring coolant temperatures with gauges and/or data logging is strongly recommended to ensure that the system is adequate and the turbocharger is supplied with water or coolant at a temperature below approximately 250°F (121°C) on the input side.

Vehicles with extremely low exhaust gas temperatures and no water cooling system (low-output diesels or purpose-built methanol / alcohol fueled dragsters, for example) may not require a water-cooling system for the turbocharger. In this case, the condition of all turbo components should be closely monitored to ensure the bearings remain in good condition and oil coke is not forming. If in doubt, set up a simple water cooling system. In summary, water-cooling is an important and fairly straightforward requirement for turbochargers that are equipped with water ports. The consequences for overheating a watercooled turbocharger can be intensely destructive, and the reward for a thoughtfully laid-out water-cooling system in good working order is a turbocharger that will be allowed to live the longest life possible under the extremely demanding conditions that it must endure. By making a modest effort to plumb water lines to your turbo, you are giving it a fighting chance at survival in your high-performance vehicle."

- Garrett, "Water cooling for your turbo"

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I threw the kitchen sink at my GT35R I got from Turbo Kraft.
Turbo Kraft check ball
Clewette scavenging pump
Custom thermostat controlled water cooling. KTM Radiator w/fan, Ford GT500 supercharger water pump and t-stat controlled.
Pump and fan cycle a few times after shutdown.

I guess I got my custom timing curve right too. 6,000 miles of abuse and going strong.

TOOT TOOT! :D :D


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Interesting reading.

Garrett has updated that info on their website. The prior document discussed the minimal effect of coolant on a *running* engine, i.e. the amount of heat transfer from the turbocharger to the coolant with sample coolant inlet & outlet temperatures. The take away was that coolant is mostly important for reducing heat soak and coking of the oil after engine shutoff.

Garrett also used to not recommend installing the turbochargers at an angle greater than 15deg, but now promote 20deg as the suggested angle for a passive cooling system (no pump).

Thanks, this has inspired me to put together a cooling system on a 911 Turbo fitted with a GT35R. It's got EFI with channels to spare, so we'll monitor and log coolant temps in & out, on both a passive and active cooling system. I'll post results when done.

In the meantime: it's really hot here in AZ and these turbochargers have a 16+ year track record of holding up just fine without a cooling system installed. We're not gentle on these cars. Take from that what you will.

It's that dry heat

Smile wavy

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So maybe I was using wrong size restrictor (0,8mm)? If so, what size restrictor is recommended?

Good to know, thanks for clarifying.

OK, then no real advantage to Clewett's over the stock pump - except for the cam sync sensor, which is the main reason I had it anyway :D

LOL - I hadn't even interpreted the original wording as meaning "fill the water jacket with oil", given that's widely understood to not be a good idea - but I see now that it could be read that way.

Yeh, wasn't thinking of doing that...

Well, can't argue with track record and real world experience, and I don't plan to - thanks!

I hadn't read the Garrett article before, and actually found it very informative - the most reassuring thing for me was that it didn't read "run our turbo without coolant in the water jacket - are you freaking insane!?!?" as I had expected, but rather "lots of folks do this, its an option".

Also made it clear that critical time for heat damage (assuming correct/decent operating conditions) is heat soak after shutdown - so if a sensible cool down regimen is observed after extreme usage, everything should be fine.

Appreciate it!

:D Only 110F/44C today.

Can someone tell me how much oil per minute should come out of turbo oil feed port? I have 3bar pressure there on idle, but only about 250ml per min of oil getting out(without restrictor). That seems to be too little. Could someone share what is normal oil feed amount and what could cause that lack of oil capacity?