Rusty,
If you
really want to run the evaporator core as your oil cooler, why don’t you move
the oil filter upstream of the cooler.
That would reduce the pressure to the cooler, and also eliminate some
downstream restriction.
Steve Brooks
(running the stock oil cooler)
-----Original
Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net]On Behalf
Of Russell Duffy
Sent: Tuesday, September 07, 2004
4:59 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] high oil
pressure and coolers
Greetings,
I just
called Bruce to ask a few questions related to oil temp and pressure, and I'm
not sure I feel better now.
First,
he still says he wouldn't run over 210F. I was of course hoping that he's
say it was OK to run more.
Next, I
was asking about how the oil pressure regulator worked, and got an
education. While this may not be news to some of you, others will find it
as disturbing as I do. The engine has two oil regulators. In my
case, the normal regulator is set at about 75 psi, and is at the inlet of the
oil to the engine. The other regulator is in the front cover, to regulate
oil outlet pressure, and is fixed at 157 psi!!! This is to allow for
restriction in the oil coolers and long lines. He said you'll see this
when cold, and likely during that first climbout, but he didn't believe it
would stay that high all the time. He did think it would always be over
100 psi though.
I'm
really concerned about the evap core in the current installation.
First, it just failed, as did Dave's Setrab (rated up to 232 psi). How many
other non-Mazda oil coolers have failed?
In my
case, I have other causes for concern. My oil goes from the engine, to
the evap core, to a Peterson inline filter, back to the engine.
Along the way, I do a couple restrictive things. First, I start
at AN12, then change to AN10 at the outlet of the filter. That
probably causes some restriction, but perhaps not as much as the oil filter
itself. The Peterson filter is a stainless mesh filter, which normally
comes with a 60 micron screen. I was concerned about that being too
big, and changed to a 45 micron screen. This will certainly be more
restrictive, but the Peterson filters are very high flow to start with, so
maybe this isn't an issue. Nevertheless, I'm concerned that I've caused
enough restriction to make the oil outlet pressure stay near it's 157 psi
limit at high rpms.
The
next problem is not knowing what the evap core can handle. The more I've
thought about it, the more I don't think the evap core routinely sees pressures
over 90-100 psi in the car. I also worry that pressure pulses in
gas are far more forgiving than they will be with liquid. Who knows
if there are pulses in the oil pressure that even exceed the 232 psi rating of
the Setrab. Anyone know what the stock Mazda coolers are rated
for.
I'm
probably not going to fly again, until I have a pressure gauge on the
oil outlet of the engine, so I can read what pressure the evap core is
seeing. The VDO senders seem to skip from 150 psi, to 350 psi, so
there isn't a great choice. I'm even considering not flying the evap
core oil cooler again regardless. I already know it isn't going to work
well enough for my current power level, so why take a chance.
Has
anyone checked the pressure out of the engine? What do you guys think
about all this?
Thanks,
Rusty
(this is why I needed another plane)