Message
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)