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Re: REFLECTOR: Re: Low RPM's
In a message dated 9/18/98 3:43:19 PM Pacific Daylight Time,
> BTW, I just did a trip from Denver to New Orleans to Tampa to Sebastian
> to Miami and back to Denver. No problems with either the Franklin
> engine or the IVO prop. My only complaint is the oil breather is
> allowing too much oil to go overboard. I bought the cheap Spruce oil
> collector and saw no difference. I guess I will try to design my own.
> Any suggestians would be welcome.
I made a vapor/oil seperator for my old race bike that also used a crankcase
evacuation system. The set up started in the collector of the exhaust. A tube
with a 45 degree angle cut on the end was welded into the pipe. The 45
cutaway faced the exhaust port of the engine rather than the outlet of the
pipe. I wanted to use the weaker return wave to evacuate the engine rather
than the stronger power pulse which would have made it more likely that oil
would have been drawn out with the exhaust.
This was connected to a suction check valve, which was nothing more than a
check valve off of an old Chevy air injection system. Cheap and available. The
check valve would allow a negative pressure wave to develope in the system
without letting a positive wave develope. This was then plumbed into a
canister that also connected the breather hose from the engine and a liquid
drain back line lower than the breather lines. Inside the canister was a
baffle plate that forced the incoming oil to hit it and bend around it in
order to get to both the drain back and vent line to the exhaust. The canister
was filled with a product called "Explo-safe" which is a mesh material that in
used inside of fuel tank to prevent sloshing. The material allowed the liquid
in the vapor a place to collect thereby insuring that the vapor heading to the
exhaust was only de-oiled vapor.
The result? When the engine came up to 2000 rpms, the breather line to the
engine went into vacuum which is exactly what it is supposed to do. What
benefits do this system bring? Besides insuring that the crankcase never sees
a positive pressure and reducing oil leaks, the main as far as racing was
concerned was that it allowed me to use a two ring piston: one compression
ring and one low tension oil control ring. As a LARGE amount of power is
consumed in the ring package, any reduction in the amount of rings or tension
is welcome in a race motor, not that this is what is needed in an aircraft
One of the best things that ever happened to the automotive engine was the
development of the PCV system. The PCV system flushes all of the blow-by gases
out of the crankcase and routes them into the intake to be burned. This keeps
the oil fresher from contaminates that bring about babbit bearing wear. I
don't know if aircraft engines have a PCV system, but as we can pretty much do
whatever we want, I would be a strong advocate of such a system being
developed if needed.
Hope this gets the creative juices giong...