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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)
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