Since Mazda is thinking of running the engine up side down in the
 new car soon to be introduced I was thinking of the best rotation for
 use in an aircraft.

 That has to be with the exhaust port pointing down. That gets the
 exhaust heat out of the cowl as soon as possible. The problem with
 the stock center housing is rotor cooling oil drain back in that
 orientation. In early days I fought against it for that reason.

 Also an off the shelf dual throat Webber 52 mm down draft carb can
 be used with a p-port in a very simple manor. That allows moving the
 engine up 2 inches.  More on this shortly.

 Here is a cut away center housing showing the cooling oil drain
 backs from the rotors. That is the main factor the orientation of
 the engine.

 If we are building our own aluminium center housing that should be
 the way to go. No oil pan is necessary just an after market dry sump
 pump system. One AN line from the bottom of the center housing can
 scavenge all rotor cooling oil.

 An AN dash 16 is shown in the TTC engine oil plumbing but a dash 8
 would be plenty big enough for 250 HP.

 All that breather and oil filler part can be done away with in the
 center housing. Greatly simplifying it.

 Paul Lamar


Hi Paul, what is the history on engine pic Eng1A.JPG ?

Steve Carlisle

That goes back about 17 or 18 years. In those days they called it plugs
up. The oil pan and rotor cooling oil drain backs were big problems.

Lew Ross original Moony installation in 1973 used that orientation because the crank
angle sensor or distributor  stuck way up over the top of the rotor housing. Later
engines did away with that crank angle sensor and the distributor of course.

Here are a couple of 3D's with the exhaust down and the dry sump
oil system with direct oil scavenging. That was Jim Mederer's idea on
the TTC engine. The dry sump is not drawn in yet. This depends
on a new center housing designed to allow the cooling oil
to go straight down.

It gives a much cleaner installation with lots of room for a cooling
system on the right side of the engine. What I am most pleased
with is the possibility of using a 52 mm down draft  Webber carb or Webber copy.
This is going to make the installation much much quicker as
no messing around with a $1000  EFI. Very straight forward
and reliable just like an aircraft engine almost.

This the ball jointed universal motor mount that fits all aircraft.
Totally adjustable so the prop shaft always comes out of the
center of the hole in the cowl. Much cheaper to ship as it fits
in a mailing tube. A traditional welded motor mount requires
a 3 foot cube box which shipping on that can b several hundred
dollars.

Paul Lamar

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