journal bearing + oil restrictor = fail / or bad turbo - Page 2 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 03-25-2008, 01:12 AM   #21
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Actually Corky is the one that told me you need hardly any oil at idle. Here is exactly what he said, YMMV:
Quote:
The oil pressures suggested are not a problem. Even the zero pressure at idle is okay.
He also said:
Quote:
Consider:
1. Turbos do not spin very fast at idle. 100/200 rpm. Loads are near zero.
2. Oil does not drain out of the bearings when sitting still. Oil only leaves the bearings when new oil is forced in from the pump.
3. Turbos do not "wind down"... the Aerodyne being an exception. As soon as the engine goes to idle, the turbo will be at idle in a second or two.
4. Water cooled center sections keep oil cooler than the charring temperature.
5. Synthetic oil has a charring temp so far up the scale as to be .... safe.
6. When oil begins to suffer some damage from high temps, change oil. That works out to be about a 6,000 mile interval in my best guess. (synthetic)
7. If no water cooled center section is present, change oil every 3,000 miles.
8. No turbo racer uses turbo timers. Slightly different deal, but the Audi Diesel that just won Le Mans ran just about an equivalent 3,000,000 street miles, and they didn't even change the oil.
9. When stopping immediately from use of boost give the engine 30 seconds at idle then turn off.
10. When parking in your own driveway, turn it off and walk away.
11. NEVER turn it off while under boost.
12. Be careful with excessive ignition retard, as that can drive exhaust gas temperatures beyond imagination. Some of which will eventually get to the oil.
13. Porsche does not use a turbo timer, and I'll copy them anytime.

I'd urge that many better ways exist to spend a buck. Margaritas, for example.

In 30+ years of playing with turbos, I've not failed a single one. I've never mustered the patience to even do as I have suggested above.
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Old 03-25-2008, 01:13 AM   #22
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Well I heard that journal bearing turbos don't need restrictors which is where. Maybe all the turbos that are run on the DSM the SS lines are restricted enough but I do know that when swapping to a BB turbo that the DSM guys have to install a restrictor. My first idea would be the restrictor causing the problem. Weird that a few of you are smoking with out one.

I agree with a few, time to upgrade that turbo. T-67 time. haha
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Old 03-25-2008, 01:25 AM   #23
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Quote:
Originally Posted by cjernigan View Post
Actually Corky is the one that told me you need hardly any oil at idle. Here is exactly what he said, YMMV:

He also said:
the man may be right. maybe he is too perfect. saying that you never fail is like saying he is god. not to pick on the guy but he knows his stuff. i am still learning. what i know about the bearings so far makes me believe that we both may be right everyone got their opinion i'll consider yours but will stick to mine. lol.

ps i hope you don't have 0 pressure at idle or anyone else.
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Old 03-25-2008, 01:30 AM   #24
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Quote:
Originally Posted by musanovic View Post
the man may be right. maybe he is too perfect. saying that you never fail is like saying he is god. not to pick on the guy but he knows his stuff. i am still learning. what i know about the bearings so far makes me believe that we both may be right everyone got their opinion i'll consider yours but will stick to mine. lol.

ps i hope you don't have 0 pressure at idle or anyone else.
Actually my old turbo was fuxored, installed a OPG inline with the feed line. After a hard run the oil pressure would go to zero for some odd reason. That's not the case anymore, it had issues that didn't make sense.
I don't consider him god, but he has spent more time with turbos of all shapes and sizes then pretty much everyone on this board. It might not be gospel, but it is worth reading.
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Old 03-25-2008, 09:39 AM   #25
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I did homework for weeks on the pro's/con's of a restrictor. I called ATP and they said based on your particular car's oil pressure and oil feed line size, you may or may not need one. I concluded that the oil pressure we see in the Miata in the high-rpm range and my purchase of a -4an line dictated I needed a restrictor. I was blowing oil through the seals without the rivet in place, and after the being installed, no more leakage.

m2, I hate to say it, but I'd bet that turbo was worse off than you thought when you bought it. The .065 restrictor should provide plenty of oil for a JB turbo, and it clearly wasn't being over-oiled.

Everybody has their own opinion about restrictors (even Corky). Here's a good discussion and how I did the restrictor thing: https://www.miataturbo.net/forum/showthread.php?t=6116
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Old 03-25-2008, 10:31 AM   #26
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Default my mistake(s)

First I think I should have run this turbo without the restrictor. I made the assumption that because the previous rebuilt china charge smoked w/o a restrictor this turbonetics would to. IF I did go with the restrictor, then I should have verified the hole diameter. Never considered that there was another smaller restrictor that could have been sent to me accidentally. And finally I could have checked flow out the drain to verify good oiling.

So now, I'll go ahead let the car idle with the drain visible so I can see oil flow. I'll video this for opinions, but I've seen video of unrestricted oil flow to a journal bearing Holset for comparison. That'll be a good indicator of problem. Then I'll pull the center and compressor as an assembly. I'm hoping at this point my turbine blades are untouched. But I'm also considering just getting another assembly/turbo so I can do a swap and minimize downtime - repairing this one later. But I've got to figure out what the problem is first.

Sam- this turbo really was pristine. I have total confidence in the person I bought it from (not an eBay deal). Something has caused the bearings to wear prematurely as there's about double the shaft play there was a thousand miles ago.
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Old 03-25-2008, 10:35 AM   #27
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m2-when you installed the turbo, did you run synthetic right away? or did you break it in with conventional oil and then switch to syn.?
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Old 03-25-2008, 10:37 AM   #28
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^Gotcha.

You're gonna be surprised at how much oil flow there is. I decided to see one time how much there was... disconnected the oil feed from the turbo and stuck it in a milk jug on the floor. I turned the key and started the engine, then quickly got up and looked. It had pissed about a quart into the jug in the 5 seconds it took me to get out of the seat and look under the hood. I couldn't shut the car off fast enough.
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Old 03-25-2008, 10:40 AM   #29
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sam-whaaaaat? maybe the -4an is just too much?
and this is with the .065 restrictor you run or without?
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Old 03-25-2008, 11:03 AM   #30
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Sam- that's what I hope I don't see (unfortunately) because that would explain the source of my failure. I'm running a 3/16" hose (-3an) - but that's nearly 3Xs the size of the restrictor bore - so there's got to be a big difference in flow. Here's the Holset I mentioned - notice the flow and how long it continues to flow after the starter stops. This is only at starter rpm.


IMO, the best advice for using a restrictor is to determine whether you need it or not BEFORE buying/installing one. This based on how many are and are not running one on a journal bearing turbo.

whaaam- turbo was low mile used, no break in needed, it was in prime condition

Last edited by m2cupcar; 03-25-2008 at 01:58 PM.
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Old 03-25-2008, 12:41 PM   #31
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Default Garrett says:

from their turbo FAQ:


Does my turbo require an oil restrictor?
Oil requirements depend on the turbo's bearing system type. Garrett has two types of bearing systems; traditional journal bearing; and ball bearing.

The journal bearing system in a turbo functions very similarly to the rod or crank bearings in an engine. These bearings require enough oil pressure to keep the components separated by a hydrodynamic film. If the oil pressure is too low, the metal components will come in contact causing premature wear and ultimately failure. If the oil pressure is too high, leakage may occur from the turbocharger seals. With that as background, an oil restrictor is generally not needed for a journal-bearing turbocharger except for those applications with oil-pressure-induced seal leakage. Remember to address all other potential causes of leakage first (e.g., inadequate/improper oil drain out of the turbocharger, excessive crankcase pressure, turbocharger past its useful service life, etc.) and use a restrictor as a last resort. Garrett distributors can tell you the recommended range of acceptable oil pressures for your particular turbo. Restrictor size will always depend on how much oil pressure your engine is generating-there is no single restrictor size suited for all engines.

Ball-bearing turbochargers can benefit from the addition of an oil restrictor, as most engines deliver more pressure than a ball bearing turbo requires. The benefit is seen in improved boost response due to less windage of oil in the bearing. In addition, lower oil flow further reduces the risk of oil leakage compared to journal-bearing turbochargers. Oil pressure entering a ball-bearing turbocharger needs to be between 40 psi and 45 psi at the maximum engine operating speed. For many common passenger vehicle engines, this generally translates into a restrictor with a minimum of 0.040" diameter orifice upstream of the oil inlet on the turbocharger center section. Again, it is imperative that the restrictor be sized according to the oil pressure characteristics of the engine to which the turbo is attached. Always verify that the appropriate oil pressure is reaching the turbo.

The use of an oil restrictor can (but not always) help ensure that you have the proper oil flow/pressure entering the turbocharger, as well as extract the maximum performance.
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Old 03-25-2008, 01:54 PM   #32
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yeah if corky is saying a journal bearing needs no oil pressure, he's wrong. liquid oil type journal bearings are designed to work with pressure. the oil IS the bearing.
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Old 03-25-2008, 02:02 PM   #33
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Quote:
Originally Posted by y8s View Post
yeah if corky is saying a journal bearing needs no oil pressure, he's wrong. liquid oil type journal bearings are designed to work with pressure. the oil IS the bearing.

Just to clear things up, Corky said 0 oil pressure at idle would be ok....
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Old 03-25-2008, 02:12 PM   #34
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Just to clear things up, Corky said 0 oil pressure at idle would be ok....
doesn't matter... metal on metal at "a few hundred rpm" is still metal on metal.

imagine your crank or cams with 0 oil pressure at idle. even in neutral with no accessories, there's still a load on the journals.

the turbo will have a load (even small) on its bearings too. it doesn't take long to gall I would bet.
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Old 03-25-2008, 02:14 PM   #35
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if i stop my wheel from spinning at idle, it barely wants to spin again if i let go....

his comment was that it wont hurt the turbo, there is enough residual oil left over that it wont seize up or wear down....prolonged like that...then i dunno, probably not.
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Old 03-25-2008, 04:13 PM   #36
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i talked to a professional and i mean he only does turbos. when you talk to the guy you can sense that he know his stuff. if anyone has questions about a restrictor call the man up.

Turbo Exchange and Performance
1800 377 6605
Concord NC. His name is Andre
www.tepturbos.com
i went through him and he does amazing work !!!!!!
custom made turbos can be ordered or you can upgrade your own.
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Old 03-26-2008, 12:19 PM   #37
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Default oil flow

Here's the oil flow video at idle, warm. Looks like plenty of oil to me. Sam- what'd yours look like? Anybody else?
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Old 03-26-2008, 12:45 PM   #38
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looks ok to me. have you checked that the shaft is still in one piece? ie it spins with the car running?
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Old 03-26-2008, 01:07 PM   #39
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Oh yeah - it spins as good as it ever did. Shut the car off and it just spins and spins. I had to do a double take Monday after spinning it with my figures. It spun so well (as always) and then I thought I saw something stuck on the edge of the blades... unfortunately it was more blade. But you can't make the blades hit the compressor housing by pressing on the shaft. That's why I suspect this issue is very recent.

I'm going to start removal and disassembly now. I'll fab up a blanking plate for the turbine center section hole. Figured I would drive it around NA and see what my temps look like in comparison to boosted since I haven't altered the oiling system since I last looked.

I've got a non restricted video to post shortly. There is a BIG difference between the oil flow with and without the restrictor.

Here's the no restrictor video:
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Old 03-26-2008, 01:41 PM   #40
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video no longer available?

is there axial play? maybe the blades dont wobble but move straight out.
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