Upside down VNT?

[regcheeseman]

I can say that all journal bearing turbos that I've seen have had the pressurized oil enter the area of the bearing very similar to the way the oil enters the main or rod bearings of an engine.  It then flows out from the limited space and is evacuated from the main cavity of the turbo by gravity.  The turbo shaft seals are not positive seals but rather rely heavily on the proper drainage and oil slingers on either end of the shaft before the seals.  If one were to pressurize the drain port I am 100% SURE that a massive amount of oil would leak out of the shaft seals when the cavity was pressurized.  I surmise that it might even be enough to actually starve the shaft bearings of proper pressurized lubrication and the turbo would not last any amount of time.

That is pretty much how I understood the setup, the only item pressurizing the the oil exiting the turbo would be the flow limitations of the drain hose and sump connection. Therefore reversing the flow should pose no problems for the seals with no change in the drain setup.

[RadoTD]

Less leakage would occur with the latter, but as the oil level rose above the shaft it would still leak out the shaft seals profusely.

Just to clarify 100% as I'll be running into something similar in my build, but if your oil return is on the top, even with nominal pressure, it will leak around the shaft?

[Vincent Waldon]

Vince, I flagged his post as soon as it was up and didn't comment for a day on it.  I have a hard time saying nothing when someone posts rudely to a forum member I respect and without presenting any worthwhile information.  I would certainly have preferred to see his post removed, but I won't sit idle for very long.

PM sent....

[fatmobile]

 Cheeseman is always messing with stuff he doesn't know anything about,.. when he starts, ha.

 Fortunately, he has a steep learning curve and we all learn along with him.

 The pressurised oil squeezes past the bearings and drops into an open cavity, that is basically at block pressure.
 If someone fed oil into the cavity, then expected it to squeeze past the bearings, the whole shaft, bearings, seals and all would be under much higher pressure.

 This has been mentioned,
 I'm simply restating it in a different way.
 

[regcheeseman]

(big chunk of very useful turbo architecture info cut)..Much like running a jet of water under your roof shingles instead of rain naturally flowing off the roof.

Now, that is an analogy I can relate to; some weeks I was woken by the wife "what the f is that running down the wall"

It transpired that a gutter discharging onto a roof at the wrong angle WILL push a hole in the roofing felt...


On a serious note, thank you for the detailed description of the internal setup, it actually gives me an understanding of what is happening, rather than accept it at face value.

Time to get clocking......pass me the big hammer and a chisel, this looks easy.

[rallydiesel]

Keep in mind your vnt actuator will now be in a different position. And hopefully not pointing at the cylinder head or you will need to make a linkage to mount the actuator up/down/or towards the firewall if you have enough clearance.

[regcheeseman]

Keep in mind your vnt actuator will now be in a different position.

VNT Actuator?  No, Mr Know-nothing Cheeseman has no use for VNT actuators.

Well, not a conventional actuator, my VNT is driven via Bowden cables so it's orientation is of no concern.

The whole lot is controlled and driven by self-designed micro processor circuit, of which I knew nothing about 24 months ago.  

[RadoTD]

Well, not a conventional actuator, my VNT is driven via Bowden cables so it's orientation is of no concern.

The whole lot is controlled and driven by self-designed micro processor circuit, of which I knew nothing about 24 months ago.  

Dude. That's pimp. Gonna be sweet once it's running!

[UAofE]

You are obviously quite new here.

You don't know whats obvious then.

Vince, I flagged his post as soon as it was up and didn't comment for a day on it.  I have a hard time saying nothing when someone posts rudely to a forum member I respect and without presenting any worthwhile information.  I would certainly have preferred to see his post removed, but I won't sit idle for very long.

I think you need to spread the cheeks a little further apart, I can still see an open nostril.

[Vincent Waldon]

I think you need to...

Zero-tolerance for blatantly disrespectful posts... *and* you were warned once (this time around?!)... account disabled.

[mr.woods]

Keep in mind your vnt actuator will now be in a different position.

VNT Actuator?  No, Mr Know-nothing Cheeseman has no use for VNT actuators.

Well, not a conventional actuator, my VNT is driven via Bowden cables so it's orientation is of no concern.

The whole lot is controlled and driven by self-designed micro processor circuit, of which I knew nothing about 24 months ago.  

Like the chevy duramax lmm vtn? they adjust the vanes to act as an engine brake too.  This is a very good build I'll keep my eye on this thread.

Oh, and, there is always a way, you just need to find out how.

[rallydiesel]

The new Audi turbos are actually controlled entirely by an electronic servo. Maybe this would be even better than bothering with vacuum on non-ecu cars.