kevin in denver, Doing a dry sump you can use the current oil pan to
collect the oil and easily scavenge it out of the oil pan with an
aftermarket gerorotor pump such as moroso sells (parker hannifin   internal
parts).This adds firewall forward weight due to the  tank  which should be
larger than the pan capacity particularly  on the  smaller RX8 pan, a
minimum
of two more hoses  which present a place  to leak, a third vent hose back
to
the engine and weight of the oil  pump and  drive.

There is an upside to this
IMHO in  that  you would be filtering and then cooling the much hotter
temp
oil returning from rotor cooling and end housings and only  this  hotter
oil.
Also you will add the pressure pump  bypass oil and be  cooling as well as
filtering it on each  pass. the stock syster has  the oil fall into the oil
in
the pan mix up with it avaraging the  temperature then  pumping it back to
the
engine without any heat   removal.

After the engine pressure pump their is a
relief valve which maintains a set oil presure and flow into the  engine.
The
oil which is surplus at the relief valve is  directed to the  engine
mounted
filter and thru the  oil cooler back to the pan.  Therefore we are
filtering
less of the oil and cooling with less  delta T at the  cooler. These
engines
reject A larger percentage of   heat to the oil than a recip because the
hottest parts (the  rotors)  are oil cooled.

The  extra 18 pounds of  hardware
would be on the accessory end of the engine and firewall  area and lessen
the
impact on the firewall forward CG. Add  the new one piece front  mount/
PSRU
adapter Paul is  developing and get the weight back.As  far as inverted
operation goes, take a  look at the internal  structure of  the
center  housing found in photos of housings  sawed in  two as  seen in this
newsletter.

Notice   that the oil path  up thru the engine from the eccentric
shaft  is of a similar size to the oil return to the pan. IMHO one  could
collect the oil from the filler tube, the top of the accessory  housing
with
some tedious drilling and tapping, or just  brute force drilling  and epoxy
a
steel tube from the  top of the rear housing down to the  oil  relief ring
inside the rear oil seal part of the  housing.

The overflow  from the engine
pressure  pump relief valve woild be sent  (check valve) through this
collection header to a separate scavenge  pump so that the pump would  be
lubricated with this oil when  flying with the rubber down. I have  not
done
this  scheeme but plan on doing so, if anyone on the news  letter  sees
something  I am missing don't be shy.

george  grimes

Keep in mind that I'm doing this in my head as I  am  TDY in Washington and
my
garage is in  Denver.

I'll have to search  through past graphics on this  board to find oil
galley
pathways to see  exactly how  difficult or easy this may be.Also, this
question was inspired   by my oogling an Aston Martin this weekend.  It has
a
dry sump system  allegedly for lateral forces during racing (or because  it
impresses wealthy  car buyers...).  Lateral forces are  not a factor for
aircraft  engines.  I suppose the 13B  factory designed sump would be fine
for most everyday straight and  level flying.

But, here's my  thought:  Remove the oil  pan completely.Create a header
system for the  oil  collection.Use an in-line pump to push the oil into
the
oil tank.Mount  the oil tank onto the fire wall (which could act as  an
additional oil  cooler/separator).

This shifts  weight back toward the CG and exposes  the underside of the
engine to air flow (not a major concern but a possible  added  cooling
benefit).With A/N tubing and fittings I don't think leaks  are  a factor,
but
complexity is indeed added to the  factory designed  system.

There is an increase in HP for  piston engines using a dry sump,  but is
there
a  major benefit for rotaries?I would think a shift of weight,   increased
cooling and increased oil capacity would be the  benefits.   Added weight
and
added complexity is  a liability.  Do they cancel each  other, or is there
a
consideration I'm missing?

Kevin in   Denver

The reason piston engine lose HP with oil in the sump  is  churning
loses due to the spinning crank. The oil in the  sump of a rotary  does
not come near the rotors or the  e-shaft.

The oil drain backs in  a rotary are several  starting in the front and
going
all the way to the   back. You will need some sort of oil pan to collect
all
this  oil.

Paul Lamar


Years ago we made  the dry sump just a flat plate. No pan. The stock pump
was used for  pressure, and a single stage scavenge pump for collecting oil
through a hole in a rotor housing leg. The stock pump was fed through  the
flat plate with a flanged fitting in the stock pickup holes.  Worked just
fine.
Good steady oil supply to the  stock pump. The line from the scavenge pump
goes  through a  filter and cooler. The same for the pressure line from the
stock  pump.

Then we got a real dry sump pump (Moroso) with 2 scavenge  sections. The
stock pump is no longer used. The front scavenge  pickup was a half circle
cut
into the side of the pressure  relief in the front cover. The normal oil
out
fitting becomes the scavenge out for the front of the engine. The  rear
scavenge  pick up is a stock oil pressure relief valve  gutted and a window
cut
into one  side. The window is  installed in the down direction and the jamb
nut tightened.   The normal oil-in, banjo fitting in the  rear iron becomes
the  rear scavenge out fitting. If there is a fear of debris  damaging  the
pump, you can install in-line bug screens.

Some  dry sump pumps have the scavenge exit each section, so you have two
scavenge out lines to run through coolers and or filters, and some run  one
section into the other inside the pump, and have only one  scavenge out
line.

A bit less complexity but either  one works fine. Peterson has a selection
of toothed belt pulleys and  belts. Also any power transmission shop has
all
of   the drive stuff. The later square Peterson pumps are no good.
The  pressure section splits open. The older round Petersons are  fine.

For inverted use I would use the stock oil filler pipe as  the inverted
pickup, using some sort of more secure cap. For long  runs right side up,
rig a
1/8 Nylon line from the pressure  pump, or any line or filter stand to feed
the  inlet side of  the inverted scavenge section, through a .015" orifice
so
it never  runs dry. One scavenge pickup for up and one for down is  fine.
The scavenge  pumps pull a huge amount of air out of the  engine and run it
through the oil  tank and then into the  breather hose and back into the
engine.
So air goes  the  wrong way through the breather hose.

Oil pressure is  controlled in the pressure pump, not inside the  engine.

You still need the ball type selector valve to pull oil from both top  and
bottom of the storage tank.

In the picture, find  the dry sump storage tank. Way too big. Later
replaced
with tank made from a hand held fire extinguisher  bottle.

Lynn E. Hanover



Lynn--what  years/class/driverdid you run this?  Have other photos of
engine
compartment and suspension/chassis and with body on it?

Steve  Beckham

I have many, if Paul wants them here or perhaps a private
transmission..........The car is a 93-95 RX-7 built to SCCA GT-3 rules. Raced  from 2000 to
2006. Driver retired.

Lynn E. Hanover