Ryan Allen wrote:
I am leaning towards routing my crankcase breather tube down to an exhaust pipe and skip the air/oil separator. Even if I install an air/oil separator, I will not return the oil to the engine. Anyone have any thoughts or suggestions and/or pros or cons on this matter?
Im curious to see if anyone has determined a best oil exit location on the Thorp airframe.
Hi Ryan,
I'm actually a Thorp wannabe, but I have stayed in a Holiday Inn Express once...
My experience comes from being a three-peat RV guy and have experimented with several crankcase vent iterations on two 0-320's and one IO-540. Early on I tried a simple line routed from the crankcase breather down to a small SS tube 1" from an exhaust pipe. This didn't work well. After some discussion an AE informed me the lower cowl area was high pressure and actually created back pressure in the line. That's when I bought an M-20 air-oil separator. I routed the exit line alongside one of my exhaust pipes and had it exit into the slipstream with a 45 degree cut aluminum tube. The drain line went back into the engine via a fitting on one of my valve covers. This setup works very well and it has a side benefit of keeping the belly clean doing sport aerobatics.
The second setup I used on my Harmon Rocket was a
Slime Fighter http://www.aircraftspruce.com/catalog/e ... imeftr.php air-oil separator purchased from Aircraft Spruce. It requires very little plumbing and works very, very well. I used the identical exit tube alongside the exhaust in the slipstream. The side benefit of having your exhaust and breather in the slipstream with 45 degree angle cuts is scavenging. It's an old Steve Wittman racing technique that works.
http://www.vafarchive.com/msg/rv4/t2006007000Give it a try, you won't regret it.
V/R
Smokey