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Thanks Ed, Steve, & Bulent: Ok, that is enough of an indication that I have
too much pressure. I am using the stock oil feed with and AN-6 line that
feeds both the turbo and the PSRU. My return line is the stock 1/2in line
for the first 6" at which point I welded on a -6 fitting and have about 4"
of -6 line.
The re-built turbo is even leaking on the outside (where the exhaust housing
attaches to the rest of the turbo). I think I will take it appart today and
make sure it is seating. Then I will put a restrictor in the feed line....
but how big? I think I'll try a 3/16 hole. If that still smokes I will cut
it down to 1/8.
Thanks for the help.
Dave Leonard
______________________________________
Minimize size for oil drain back on the turbo should be 1/2" dia (5/8" is
better), anything smaller will impede oil return to the pan. This will
cause oil to back up in the turbo and leak past the seals. If Mazda is using
the dia and length of the stock oil line feeding the turbo to reduce the
pressure then AN-6 line feeding the turbo will offer little pressure drop.
Quoting from Corky Bell in "Maximum Boost". "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. Problems of oil pressure overpowering the seal are evident in a
frequent, if not quite constant, smoking problem. Good guidelines for
virtually all turbos:
Idle, hot Min pressure 5 psi Min oil flow (gal/min) 0.1
Maximum Load Min Pressure 25 psi Min oil flow (gal/min) 0.5
Size of drain hose: Where possible, a minimum inside diameter of 1/2"
should be observed.
So as you can see the turbo does not need much oil flow nor high pressure.
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From: "Steve Brooks" <steve@tsisp.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Sunday, June 13, 2004 8:07 AM
Subject: [FlyRotary] Re: Some Taxi testing today. With oil leak.
> Dave,
> I'm using the stock turbo also and I haven't had any trouble with burning
> the oil. I didn't remember exactly how I fed mine, so when I was at the
> airport yesterday, I pulled the cowling to take a look at it. I used the
> oil feed and drain lines that came with the engine. The feed line was
> welded to several other lines which I cut off, but the feed is about a
1/4"
> line that feeds from the far top side. With that long of a run, and given
> that the drain tube is at least twice that size, that could very well be
the
> difference. I also don't know how much oil pressure is present at the
point
> where it taps into the block. There could possibly be a restriction
there.
>
> You may want to consider feeding the turbo from the original point on the
> block, with AN4 hose, which should be closer to the original size. I
didn't
> measure the outlet tube, but I'm pretty sure that it's larger than 3/8
> (AN6). Probably an AN8 would be a better size, unless you still have the
> original drain.
>
> Steve Brooks
> Cozy MKIV
> Turbo Rotary
>
> -----Original Message-----
> From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
> Behalf Of DaveLeonard
> Sent: Saturday, June 12, 2004 1:44 AM
> To: Rotary motors in aircraft
> Subject: [FlyRotary] Some Taxi testing today. With oil leak.
>
> I got the turbo back from the re-build shop today and did some high speed
> taxi testing. I even got the tail off the ground.... :-)
>
> Cooling has not been an issue yet for easy ground testing. Coolant and
oil
> both maxed at 70C (160F).
>
> With Jim Maher's help I fixed my tach and found that I really am getting
> more than 4500 RPM. To be specific, 4700 static at 29"MAP and 5300 at 33"
> using Jim Mosur's old prop (similar to Tracy's old prop?) And that's
enough
> to fly.
>
> First flight was scheduled for Sat the 19th, but the turbo continues to
spew
> oil-smoke. I am beginning to wonder if I am feeding it too much oil.
Rusty
> says that is an internal restrictor, but looking in the oil inlet it looks
> like it goes straight to an oil gallery. I am feeding it with an AN-6
line.
> I think I should try putting in a restrictor but I don't know how big to
> make the opening. Any input?
>
> The oil return is also AN-6 (and bigger) and is all downhill to the pan.
>
> Dave Leonard - Should have gone n.a. Should have gone n.a. Should have
gone
> n.a. (not really)
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>
>
> >> Homepage: http://www.flyrotary.com/
> >> Archive: http://lancaironline.net/lists/flyrotary/List.html
>> Homepage: http://www.flyrotary.com/
>> Archive: http://lancaironline.net/lists/flyrotary/List.html
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