Mark;
I think your pressure is just fine. I
was told by Atkins that he had installed a 100 psi relief valve, and early on I
did see 100psi pressure when the engine was cool. After 40 some hours on
the engine now I see pressure of 50-60 at idly at operating temp, and about 80
at power and high oil temp.
I had my oil cooler designed and tested to
150 psi. I use dual K&N HP3001 filters on a remote mount between the
engine exit and the cooler.
Al
-----Original Message-----
From: Rotary motors in aircraft
[mailto:flyrotary@lancaironline.net] On
Behalf Of Mark Steitle
Sent: Saturday, June 09, 2007 3:54
PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Oil temp
limit
Can you address the oil pressure limits too
please. My 20B runs in the 90's (warm). Will this hurt
anything. In order to check/modify the relief valve, I would have to
remove the oil pan which means removing the engine from the airframe. If
I'm ok running in this range, I will leave it as is. I would like to hear
your take on this.
On 6/9/07, Lehanover@aol.com
<Lehanover@aol.com> wrote:
In a
message dated 6/9/2007 12:56:28 P.M. Eastern Daylight Time, ALVentures@cox.net
writes:
I guess we've had this
discussion before but to me it still seems like a grey area.
The limit has to do
with temperature, time, and limiting component.
At typical cruise
conditions I have coolant temps of 160-170F and oil temps about 20 degrees
higher. Short term climb out (1000 – 2000') I see oil getting up
215 -220 and coolant around 200. If I continue climb, I need to reduce
power to keep them at those levels; which means climb rates of 500-700 FPM with
OAT of 65F, and maybe a bit less if OAT is higher. I don't like being
limited to that climb rate when I have power for considerably more; but the
real question is: Is that temp level an issue if sustained for 10-15 minutes?
And what is it affecting?
I expect to make some
modification to improve airflow through the cooler, just deciding if it is
urgent or if it can wait for another 10 -20 hrs of flying. Anytime I go east
from my airport I have to climb from 1400' to about 7000' to clear high
terrain.
Thanks,
Al
The
object of controlling oil temperature is that temps above 160 degrees begins to
reduce power as rotor face temps begin to limit cylinder filling.
The oil
temperatures in the wedge will be very much higher than the temperature being
reported on the gage. The bearing area is way over sized for the stress levels
involved and at the low RPM in aviation use, the bearings will not fail from
stress.
However
the soft overlay on the bearing face has a low melting point. Oil moving off
the bearing carries away the heat from wedge oil. In racing the higher oil
pressures used, helps perform this function.
Some
racers just machine off the overlay and run on the copper. Good bearing
material, and a high melting point. Extra clearance allows more oil flow for a
given pressure.
The
rotor face can run as high as 400 degrees, and the oil is removing most of
that.
By the
time you get to 230 degrees in the sump you are walking on thin ice, as far as
rotor bearings is concerned. You could go higher with less throttle (stress
from wedge heat) but in the end I think you need more oil cooling.
The
race car needs 90 water tops and 190 oil tops. At 100 PSI.
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