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

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Old 03-24-2008, 04:44 PM   #1
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Angry journal bearing + oil restrictor = fail / or bad turbo

I don't know what else to blame this on. Noticed about a couple of days ago that boost onset was later and peak boost too. Pulled the air cleaner neck to see the worn blade edges, shaft has about double the play it did at install. ~1,000 miles on the turbo since install (used but in perfect shape). Two years ago the restrictor appeared to be a recommended, especially for higher oil pressure. My guess is the shaft is ok, just need bearings... and a new wheel for max efficiency if there's one out there for a deal.
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Old 03-24-2008, 04:45 PM   #2
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man that sucks. I don't know of anyone who gets more broken stuff for less seat time.
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Old 03-24-2008, 04:47 PM   #3
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are you sure? i got maybe 15k in the last three years....


lamez!
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Old 03-24-2008, 04:47 PM   #4
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Looks like a good option would be to just buy a GT2860/71/etc Never a better time to upgrade!
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Old 03-24-2008, 04:48 PM   #5
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Ouch, looks like my old Greddy turbo! Sorry man. I run no restictors on my journal bearing stuff. I am mostly worried about them spinning before oil gets to them...my car sits for a while between use.
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Old 03-24-2008, 04:55 PM   #6
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Like I said, I don't know what else to blame it on. Doing lots of googling and now it sounds like restrictors are a no-no on journal bearing turbos. What led to me using it was actually the prior turbo - a rebuilt china charger from seller "down2turbo". It smoked immediately and I was told it was my high oil pressure (90psi peak). So I put the restrictor in and it stopped. Hmmm... ok so it looked like I should run one. After the chinacharger came apart, I just moved the restrictor over to this turbo, think it was the right thing to do. So here I am. I can only assume that's the issue - can't image what else would cause it. This was a quality unit from a reputable builder. Fortunately I suspected something early on so I'm guessing I'm only out bearings and compressor wheel...

Are you running a restrictor scott?

Curious to see what my oil temps are after a rebuild and no restrictor. Hmmm...See what I'm getting at?
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Old 03-24-2008, 05:04 PM   #7
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on the sr20s they always say restrictors on ball bearing turbos only
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Old 03-24-2008, 05:04 PM   #8
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No.

What size restrictor were you running? I think ATP's "journal bearing restrictor" is like .060", but I could be way off here. I had their standard .035" and drilled them out to the same size as a regular #4AN thru hole size.
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Old 03-24-2008, 05:15 PM   #9
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I am using ATP's "journal bearing restrictor" - that's where I bought it. It IS .065". I'll check the hole size in it when I take it apart.

If not the oil, then what else? My drain is massive - full size oil pickup tube flanged to the turbo center section drain port. Drops straight down, with a nice progressive curve to the pan.
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Old 03-24-2008, 05:17 PM   #10
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yes, i needed one, the same ATP one. I'm sure if i had a -3AN line i wouldn't.

Quote:
Originally Posted by Newbsauce View Post
Looks like a good option would be to just buy a GT2860/71/etc Never a better time to upgrade!

57 trim is bigger than 2071
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Old 03-24-2008, 05:20 PM   #11
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Damn, that sucks. Hope you get the problem sorted out.
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Old 03-24-2008, 05:25 PM   #12
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all i know is that journal bearing turbos do not need restrictors, and therefore i do not plan on running one
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Old 03-24-2008, 05:25 PM   #13
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I needed and run an oil restrictor on a journal bearing garrett turbo.

Maybe you got dirty oil into it and clogged the hole? Otherwise... majority of people I know with journal bearings run them with restrictors without issue.
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Old 03-24-2008, 05:31 PM   #14
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Quote:
Originally Posted by whaaamx5 View Post
all i know is that journal bearing turbos do not need restrictors, and therefore i do not plan on running one

"Too much oil pressure can create problems with turbos. It is possible to force oil past oil seals that are in perfect condition if oil pressure exceeds 65 to 70 psi at the turbo. If a particular engine creates more oil pressure than the seals can handle, it may be necessary to install a restrictor or bypass system to reduce pressure at the turbo."
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Old 03-24-2008, 05:32 PM   #15
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Ok... so the journal bearing restrictor theory is about in the same state.
I hope it's not dirt. The source is immediately after the oil leaves the filter and enters the block. But anything is possible.

What about compressor surge? Could that cause bearing damage? Although my guess is that the surge noise I heard today (what really sent me to investigate) came after the excessive shaft play.

One thing I could do prior to pulling it apart is install a clear drain hose on it to get a visual of just how much oil is leaving the center section.
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Old 03-24-2008, 08:36 PM   #16
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Try that, see what kind of oil flow you're getting. I run my journal bearing turbo without a restrictor but only because it doesn't smoke.
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Old 03-24-2008, 08:38 PM   #17
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-3AN line is a PITA to source, but it definitely solves the issue of possibly over-oiling a journal-bearing turbo with a -4AN line and no restrictor. I ran a -3AN and no restrictor on my journal T25, now running a .035 restrictor on the BB 2554.
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Old 03-24-2008, 10:52 PM   #18
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Quote:
Originally Posted by Braineack View Post
"Too much oil pressure can create problems with turbos. It is possible to force oil past oil seals that are in perfect condition if oil pressure exceeds 65 to 70 psi at the turbo. If a particular engine creates more oil pressure than the seals can handle, it may be necessary to install a restrictor or bypass system to reduce pressure at the turbo."
yes but how about when you are idling or have less oil pressure than 65? you are starving the turbo of oil. right? i think as long as you brake the turbo in right you should be fine with oil pressure that the miata makes. i am running without a restrictor. and it seams fine.

ps. op i really hated to look at the pictures. damn it sucks. if you are considering rebuilding it we have a great company here in NC that does great work i have experience with them, they can even upgrade your turbo with better wheel and do some porting.
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Old 03-24-2008, 11:27 PM   #19
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No you are not starving the turbo of oil when you're idling. The turbo needs a couple drops to be fine at idle. It isn't under much load and JB turbos hardly spin fast at idle.
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Old 03-25-2008, 12:35 AM   #20
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Quote:
Originally Posted by cjernigan View Post
No you are not starving the turbo of oil when you're idling. The turbo needs a couple drops to be fine at idle. It isn't under much load and JB turbos hardly spin fast at idle.
how about cruise ? i don't know about yours but mine spins pretty fast during idle i can feel air coming out of the charge pipe ....i don't think couple drops are enough though. but than again we are no experts.
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