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DIY Turbo Discussion greddy on a 1.8? homebrew kit?

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Old 11-05-2008, 10:28 PM   #1
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Default Need some catch can answers

Ok, I've read SamNavy's post about his PCV breaking and nearly jamming his cams. I've read the 'ghetto' catch can installs, I've seen brass PCV's, check valves in line with PCV's, etc, etc.

I need to know, FOR MY APPLICATION, what the best solution is. I race my car, its pretty much the only thing I do with it. I do drive it to and from the track, and once in a while (less than 1k miles a year) I drive it to work, or to the store.

My state does have emissions, but no visual inspections.

I currently have a stock Mazda PCV from the intake manifold to the valve cover, and a small filter on the exhaust side of the cam cover.

At my last track day, I was getting oil in the hot side of my intercooler pipes. My little filter was dry. I checked my PCV and it was still intact. If it helps, I have a -8an oil drain

I don't fully understand all the pressure's that are happening with a turbo system, and am afraid if I try something, it will either not solve my problem, or cause another, please advise. Thank you in advance for your help
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Old 11-05-2008, 10:46 PM   #2
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only place the oil would be coming from would be from the turbo itself in this case.
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Old 11-05-2008, 11:07 PM   #3
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is that an indication that I have bad oil seals? or perhaps too much oil pressure? I've read about putting a pop rivet in the oil line, but am unsure what circumstances require one.

if I solve whatever problem that might be, is there still any reason to install a catch can?
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Old 11-05-2008, 11:29 PM   #4
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PCV valve is working properly. Check.
Rings are good. Check.
Oil drain is properly routed. Check.
Not over-oiling (from too large a line or too much pressure). Check.

Still getting blowby on the hotside = bad compressor seal.

You can install a catch-can on the valve-cover breather line for *****&grins and when you don't find anything after a couple days of living in boost... it'll be a confirmed bad seal.

If you were over-oiling via too much pressure or backpressure (through improperly routed drain), I have found almost always that the dynamic seal on the turbine side will leak before the compressor side, and the back half of the CHRA and turbine will be covered in oil.

If you're interested in the pop-rivet, you've got the choice of aluminum or steel. The aluminum will seal better because it's softer and will conform better when you clamp it down between the fitting and the line. Steel will last longer... but they're about .08cents each. I've had an aluminum one installed for 10k miles... well, I did before I sold it.
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Old 11-05-2008, 11:39 PM   #5
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I have a variety of rivets, I should be fine there. should it go between the block and feed line, or the banjo adapter and feed line?

Sam mentioned that from over pressuring the back half of the CHRA and turbine would be covered in oil, which means that is not what is happening to me, correct? kinda sounds like I have a greddy turbo rebuild in my future.

I'm also rerouting my drain line, it was all vertical, however it had one very nearly horizontal place (maybe 5-10 degrees from horizontal) perhaps under high g cornering it was backpressuring and coming out that way. I have a tapped pan, I'll now have a line straight down from turbo to pan.
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