Interesting Rusty.  My take on the oil pressure is that the restriction of the oil cooler (evap core) is not a big factor.  Who cares whether the pressure is dropped by the cooler or the oil pressure regulator? (until it drops it below regulator spec of course)  My guess is that the after cooler pressure will be the same as long as it is above you regulator spec.  My 2nd gen was 70 psi and FWIW, I think this is enough for a NA engine running 7000 rpm or less.  Wish I could trade my 100 psi Renesis regulator for the old 70 psi without taking everything apart.  It's just wasted HP I think.

 

What really concerns me is the poor oil cooling you are getting.  I plan to use an evap core for the 20B and on my mental scratch pad, it should be better than the Mazda oil cooler in aircraft applications.   Wish I knew what the air pressure in front & back of your cooler is.  Pressure recovery is real important with evap cores.

 

Tracy

----- Original Message -----

From: Russell Duffy

To: Rotary motors in aircraft

Sent: Friday, September 24, 2004 8:23 PM

Subject: [FlyRotary] oil filter, pressure test, ewp

Greetings,

 

I installed the test fitting and gauge to read the oil pressure as it comes out of the engine, before the oil cooler and filter.  The current filter was the Peterson inline 45 micron screen.  This is suspected to be too fine for use on oil, and was later changed to a 60 micron screen. 

 

Test run 1- (45 micron screen, Mobile One 15w50 oil)

2000 rpm, 100 degree oil into the engine, 88 psi before cooler and filter, 78 psi after (10 psi diff)

6000 rpm, 160 degree oil into the engine, 110 psi before cooler and filter, 84 psi after (26 psi diff)

 

Test run 2- (60 micron screen, Mobile One 15w50 oil)

6000 rpm, 150 degree oil into the engine, 115 psi before cooler and filter, 84 psi after (31 psi diff)

6000 rpm, 180 degree oil into the engine, 105 psi before cooler and filter, 82 psi after (23 psi diff)

 

It’s impossible to be too accurate with the before cooler pressure reading, since the gauge skips from 90 psi to 150.  Anything in between is sort of an estimation. 

 

Oil temp seems to make the most difference.  Best I can tell, changing the oil filter screen to a larger size didn’t make any difference, which suggests that it wasn’t my primary restriction.  That pretty much leaves the evap core, but it’s impossible to tell if it’s “bad”, with nothing else to compare it against.  There's going to be some resistance, but how much is too much?  Either way, 115 psi shouldn’t damage the evap core, so I feel comfortable flying it again (when I re-skin my rudder and left aileron).  I also want to try 5w30 oil to see how that does, both in pressure, and cooling ability.  Maybe I’ll do that tomorrow.  

 

I was happy to note that the ewp fittings aren't leaking at all.  This just proves that if I weld something enough times, eventually I can make it stop leaking.  I was sort of hoping the water temps would seem a little lower today, with the ewp running, but I can't say that's the case.  The temps REALLY shoot up at full throttle on the ground. 

 

Cheers,

Rusty (congrats Paul, imagine what it will feel like to actually fly it)