raene

I'm suffering from what seems to be some horribly blown seals in my turbo so I've been doing some research on oil feed restrictors. I know it's not my oil return; I've pulled it immediately after shutting the car off and it was practically dry at the top (it's a -10 AN return with no kinks). It's a -3AN feed and these seem to be perfectly sized for the turbo as well.

However it seems to me that half the problem is that the oil return line is going to be slightly (or greatly?) pressurized if the crankcase ventilation isn't up to par. Seems to me that unless the crankcase is operating at near atmospheric there's going to be some pressure built up inside the oil return line that will escape through any path possible, including through the turbo seals, allowing oil to pass as well.

When I first put the turbo on I left the PCV setup stock and ran only the VC vent, which quickly became severely oily. It even got to the point of allowing oil to seep past the cam seals and VC gasket and down the side of my block, so I know I had to be developing some serious crankcase pressure. Could this have been an example of what I was describing above? Or am I smoking crack again.

I'm unsure what would happen when the 65 psi of oil meets 8psi of boost at the oil return. Or would it just be cancelled by the boost within the compressor housing?

Discuss if you please

Jared

first, you shouldnt ever seen full oil pressure, or especially any boost pressure at the oil return. sounds like you got a bad turbo, or you have extreme blowby. have you done a leakdown test on this engine?

hondaguyef

Just sounds like horrible blowby. Like Jared said, Leakdown test .

Phil

SOHC_MShue

i haven't had any excessive amounts of oil come out of my breather filter since i've had the turbo. I would do a leakdown like they said because it sounds like you are getting a good bit of blowby.

raene

I have both a compression and leakdown tester and it's got 5.5% leakdown at the worst cylinder (#1) with part of that being rings and part being valve seals; mainly rings. The best is 4%. Compression tests at 210-220 across the board.

In other words, the engine is healthy but slightly worn. I also haven't seen much oil (if any) from the VC vent since I started running with the oil separator open to atmospheric.

I'm not concerned about the mechanical soundness of my engine, more the theory that I have presented above

hybridsol

[excuse on not being clear] I'm tired, but...

The stock Honda crankcase vent system (PCV) only works when the engine generates vacuum (part throttle and idle)

Under boost, the entire block is under pressure, hopefully it won't find a way out... removing the PCV valve gives it a way out (the PVC will close when the IM pressure is greater than the block pressure)

Blowby will result in oil being blown up through the crank area into the head... and out the PVC valve hole if you removed it- the reson people use a separator can of sorts

Oil drains under gravity from the turbo- since the pressure in the oil pan/crankcase area is the same throughout the block, is has no effect on oil drainage, unless something is very wrong

Blown oil seals (in turbo) will cause exhaust smoke when going from boost to vacuum b/c the block still has pressure in it that pushes out through the exhaust seals, via the drain line

You can run an engine with much greater leakdown that what you have without problems- with the numbers you have, your engine is in very good condition

Hope I wasn't an idiot

raene

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">The stock Honda crankcase vent system (PCV) only works when the engine generates vacuum (part throttle and idle)</TD></TR></TABLE>

I don't think that's quite right since the stock engine'll pull a little bit of vacuum even near wot, but whatever

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">Under boost, the entire block is under pressure, hopefully it won't find a way out... removing the PCV valve gives it a way out (the PVC will close when the IM pressure is greater than the block pressure)</TD></TR></TABLE>

We WANT the crankcase pressure to find a way out Hence we attempt to overcome the inadequacies of the stock system.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">Oil drains under gravity from the turbo- since the pressure in the oil pan/crankcase area is the same throughout the block, is has no effect on oil drainage, unless something is very wrong</TD></TR></TABLE>

See, that's what I'm curious about... if the drain gets partly covered or fully covered, crankcase pressure will be different than air pressure in the oil drain.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">Blown oil seals (in turbo) will cause exhaust smoke when going from boost to vacuum b/c the block still has pressure in it that pushes out through the exhaust seals, via the drain line</TD></TR></TABLE>

See, that's an interesting choice of words. The block has pressure in it that pushes out through the exhaust seals. That's what I'm interested in... is there anything else you can say about it?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">You can run an engine with much greater leakdown that what you have without problems- with the numbers you have, your engine is in very good condition</TD></TR></TABLE>

heheh, thanks

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hybridsol &raquo;</TD></TR><TR><TD CLASS="quote">Hope I wasn't an idiot </TD></TR></TABLE>

Hell no, I'm looking for discussion like this. Thanks!