where'd my boost go?
 

I just drove from ATL to Daytona to FL west coast and back to ATL. Not a single hiccup with the car. Ran right up to boost target and held it every time it was asked. Get home yesterday, park the car, then get in it this morning to go to the dentist and peak boost is 4-5psi. WG can is 10psi. Wtf? I was wondering how long it would be until I got a manifold leak, but I can't hear one. There's no noise like an intercooler pipe leak. All the NA power is there. BOV sounds like it's working properly. My old bosch leaked and it sound like a pipe leak.

The only thing I noticed is that there's a couple of spots on the compressor inlet where it looks like the blade has touched. Not a full drag around the inlet but some spots that are about 1/4" long. The thing still spins like mad, the shaft play feels the same as it did when it was new. It had some, but that's typical of a journal bearing tolerance. There's no in/out play. If I push laterally (hard) on the compressor nut right after shutting the car off, the turbo is almost impossible to spin. Of course I've never tried that before, so I have no reference. I'll try it later when it's cooled down. I've had zero signs beyond that, that something was wrong with the turbo.

Thoughts? Any other ideas for boost loss?

Does it feel dry when you push and turn the shaft? I dont know if it could be an oiling issue, since a dry bearing would probably fail fast. I would think that would cause excessive drag and not allow it to opperate efficiently. Probably not what it is, but all that comes to mind right now. Odd issue.

if the turbo is hard to spin sounds like something is no gooood.

Very easy to spin. AAMOF I shut the engine off, got out, took a screw driver to the clamp holding the air filter/hose on the compressor and the turbo was still spinning. I could put enough force laterally on the nut/shaft at the compressor end to make it bind, but I've been able to do this to other turbos. I'm guessing it's just the nature of the tolerance found in a journal bearing. But I could be wrong. Anybody tried that?

I'm running no restricter on the feed line and have no smoke or any typical signs of oiling issues. I actually ran this turbo with part of the drain hose removed to check oil flow with and without a restricter. And after much discussion I couldn't think of a reason to run less oil to the turbo it was causing the typical "seal" problems you see discussed.

Here's oil flow to the turbo at idle:

Tighten all the clamps, and check to make sure the wastgate isn't stuck half open. Both have happened on my cousins car.

Good LucK!

Make an intake tester and hook it up to your compressor inlet in place of your intake pipe. Pump 10 psi through it and you'll hear the leak if there is one.

Intake Pressure Tester

Frank

Even easier -

http://www.sr20forum.com/gallery/dat...MG_2808_1_.jpg

C

WG is possibility. Intake tester sounds like a plan. I've had IC leaks before and they were very loud. This doesn't like the turbo overspinning in an effort to reach boost target... unfortunately. :( My turbo is loud as it is with the short intake and foam filter. I guess what's got me stumped is the last time I got on it was a little less than ten miles from the house on 295 and all the boost was there. I park it and this morning it's gone. :dunno: Well- I'm getting a list of things to check, that's what I need. :bigtu:

edit: sweet chriscar, visuals ftw

Rob I'd check the wastegate rod...

+1 to everything mentioned. FWIW, I made a .070" oil restrictor for my GT3271 journal bearing T3. I believe you're supposed to run a restrictor. Too much oil can damage the seals I here. But I can't imagine it seeing "too little" with a .070" restrictor. It only needs a few pounds to make a cushion. All it does is spin, no loads are put on it to push the shaft down into the bearing, other than gravity.

rofl. i had to replace my .060" restrictor for a .040" one :P

Yeah, I wanted to make a .06 but I couldn't get my drill bit that size to drill through a grade 8ty set screw. So far no smoke, but I'll probably put a .060" this summer, or sooner if there's a problem. :fingerscrossedmycarrunstillthissummer:

I was going to add the restricter back in IF I saw smoke- but it's yet to happen. So the housing is either sufficiently restricted as-is or it doesn't need one regardless. I was running one before on the previous turbo before something chewed up my turbine blades. But I can't find an argument against more oil flow if it's not causing problems.

My turbo started to shit out on me because of what I beleive was not having a restrictor.
Anyway, i was losing boost/power. No smoke, no nothing. Then about 5-7 laps later (after all of the sudden boost came back) I started having a 007 smoke machine back there and the turbo was shot to shit and I had oil coming out of my exhaust it was so bad.. Oh, but I had noticeable shaft play too.

Good luck on finding the problem.

Any thoughts on how too much oil (or oil pressure) could cause a journal bearing failure for a turbo? And the fact that it had all boost the prior day and not the morning after doesn't seem significant of a bearing failure (I hope), so I'm voting stuck internal wastegate... actually I'm praying. :D

The actual oil inlet in my chra was much smaller (~1/8") than the prior turbonetics. So it's about twice the size of the .060" restricter I had in the other one.

Too much can "wash" out a bearing. But I don't think you'd really have that problem with a turbo. I know too much oil causes seals to be damaged. I see some people have quick failures from running no restrictor. I've also seen several who go 2,3,5,8,11 months and then have a seal die, and they ran no restrictor. From all the imperical evidence I've seen, too much oil pressure damages oil seals. And most failures I see are either foreign object damage or leaky oil seals. Can't say I've ever seen people that had bearing failures they contributed to a restrictor.

Like I said, my .070" will probably be changed to something smaller. Hell, might do it this weekend.


But I'm beting your no boost problem is WG related.

You say you only get about 5psi, but where does that 5psi come? Same place as usual, or a lot higher in the rev-range?

Pat explain "wash out". If you have a given area for oil and that area is always filled to it's max, then the pressure shouldn't matter. The pressure only dictates how long a given unit of oil is present within that area.

That said, I have a shimmed oil pump and I'm running high oil pressure - it's off the gauge at redline. The engine ran near 90psi @ 4-4500rpm oil pressure my entire trip last weekend, which was around 18 hours of travel time. I do have a .060" restrictor that I ran in the last turbo which suffered turbine blade damage from who knows what. But never had an turbo oil/bearing issue prior to that incident. Just figured more oil was better if it wasn't passing the turbo seal.

That 5psi comes in a lot higher in the rev range. And it takes longer to build X amount of boost throughout the revs.

you could be seeing what I saw when I hurt my turbine....I still made boost, but only 10psi compared to the 14psi i was running, even with the wastegate fully shut I could only make 10psi.

made quite a bit of difference in my power output: http://i46.photobucket.com/albums/f1..._Mooredyno.jpg

The less boost later thing could be drag on the wheels, shaft or a leak. I made 5psi at 7k with a coupler leak, compared to 10psi at 3500 before. When my turbine wheel got chewed up it made less, but still made boost and later, but with lots of angry noises.

What happened to your turbine? can't remember.